Update PHP-CS-Fixer rules

.php_cs.dist

@@ -1,11 +1,8 @@
 <?php
 
 $finder = PhpCsFixer\Finder::create()
-    ->exclude(['vendor', 'tests/data/Calculation'])
+    ->exclude('vendor')
-    ->in('samples')
+    ->in(__DIR__);
-    ->in('src')
-    ->in('tests/PhpSpreadsheetTests')
-    ;
 
 return PhpCsFixer\Config::create()
     ->setRiskyAllowed(true)
@@ -13,21 +10,27 @@ return PhpCsFixer\Config::create()
     ->setCacheFile(sys_get_temp_dir() . '/php-cs-fixer' . preg_replace('~\W~', '-', __DIR__))
     ->setRules([
         'align_multiline_comment' => true,
+        'array_indentation' => true,
         'array_syntax' => ['syntax' => 'short'],
         'backtick_to_shell_exec' => true,
         'binary_operator_spaces' => true,
         'blank_line_after_namespace' => true,
         'blank_line_after_opening_tag' => true,
+        'blank_line_before_return' => false, // Deprecated
         'blank_line_before_statement' => true,
         'braces' => true,
         'cast_spaces' => true,
         'class_attributes_separation' => ['elements' => ['method', 'property']], // const are often grouped with other related const
         'class_definition' => true,
-        'class_keyword_remove' => false, // ::class keyword gives us beter support in IDE
+        'class_keyword_remove' => false, // ::class keyword gives us better support in IDE
         'combine_consecutive_issets' => true,
         'combine_consecutive_unsets' => true,
+        'combine_nested_dirname' => true,
+        'comment_to_phpdoc' => true,
         'compact_nullable_typehint' => true,
         'concat_space' => ['spacing' => 'one'],
+        'constant_case' => true,
+        'date_time_immutable' => false, // Break our unit tests
         'declare_equal_normalize' => true,
         'declare_strict_types' => false, // Too early to adopt strict types
         'dir_constant' => true,
@@ -38,39 +41,57 @@ return PhpCsFixer\Config::create()
         'elseif' => true,
         'encoding' => true,
         'ereg_to_preg' => true,
+        'error_suppression' => true,
         'escape_implicit_backslashes' => true,
         'explicit_indirect_variable' => false, // I feel it makes the code actually harder to read
         'explicit_string_variable' => false, // I feel it makes the code actually harder to read
+        'final_class' => false, // We need non-final classes
         'final_internal_class' => true,
+        'final_public_method_for_abstract_class' => false, // We need non-final methods
+        'final_static_access' => true,
+        'fopen_flag_order' => true,
+        'fopen_flags' => true,
         'full_opening_tag' => true,
+        'fully_qualified_strict_types' => true,
         'function_declaration' => true,
         'function_to_constant' => true,
         'function_typehint_space' => true,
         'general_phpdoc_annotation_remove' => false, // No use for that
-        'hash_to_slash_comment' => true,
+        'global_namespace_import' => true,
+        'hash_to_slash_comment' => false, // Deprecated
         'header_comment' => false, // We don't use common header in all our files
+        'heredoc_indentation' => false, // Requires PHP >= 7.3
         'heredoc_to_nowdoc' => false, // Not sure about this one
+        'implode_call' => true,
         'include' => true,
         'increment_style' => true,
         'indentation_type' => true,
-        'is_null' => ['use_yoda_style' => false],
+        'is_null' => true,
-        'linebreak_after_opening_tag' => true,
         'line_ending' => true,
+        'linebreak_after_opening_tag' => true,
         'list_syntax' => ['syntax' => 'short'],
+        'logical_operators' => true,
         'lowercase_cast' => true,
-        'lowercase_constants' => true,
+        'lowercase_constants' => false, // Deprecated
         'lowercase_keywords' => true,
+        'lowercase_static_reference' => true,
         'magic_constant_casing' => true,
+        'magic_method_casing' => true,
         'mb_str_functions' => false, // No, too dangerous to change that
         'method_argument_space' => true,
         'method_chaining_indentation' => true,
-        'method_separation' => true,
+        'method_separation' => false, // Deprecated
         'modernize_types_casting' => true,
         'multiline_comment_opening_closing' => true,
+        'multiline_whitespace_before_semicolons' => true,
+        'native_constant_invocation' => false, // Micro optimization that look messy
         'native_function_casing' => true,
-        'native_function_invocation' => false, // This is risky and seems to be micro-optimization that make code uglier so not worth it, at least for now
+        'native_function_invocation' => false, // I suppose this would be best, but I am still unconvinced about the visual aspect of it
+        'native_function_type_declaration_casing' => true,
         'new_with_braces' => true,
         'no_alias_functions' => true,
+        'no_alternative_syntax' => true,
+        'no_binary_string' => true,
         'no_blank_lines_after_class_opening' => true,
         'no_blank_lines_after_phpdoc' => true,
         'no_blank_lines_before_namespace' => false, // we want 1 blank line before namespace
@@ -80,16 +101,15 @@ return PhpCsFixer\Config::create()
         'no_empty_phpdoc' => true,
         'no_empty_statement' => true,
         'no_extra_blank_lines' => true,
+        'no_extra_consecutive_blank_lines' => false, // Deprecated
         'no_homoglyph_names' => true,
         'no_leading_import_slash' => true,
         'no_leading_namespace_whitespace' => true,
         'no_mixed_echo_print' => true,
         'no_multiline_whitespace_around_double_arrow' => true,
-        'no_multiline_whitespace_before_semicolons' => true,
+        'no_multiline_whitespace_before_semicolons' => false, // Deprecated
-        'non_printable_character' => true,
         'no_null_property_initialization' => true,
         'no_php4_constructor' => true,
-        'normalize_index_brace' => true,
         'no_short_bool_cast' => true,
         'no_short_echo_tag' => true,
         'no_singleline_whitespace_before_semicolons' => true,
@@ -97,29 +117,55 @@ return PhpCsFixer\Config::create()
         'no_spaces_around_offset' => true,
         'no_spaces_inside_parenthesis' => true,
         'no_superfluous_elseif' => false, // Might be risky on a huge code base
-        'not_operator_with_space' => false, // No we prefer to keep '!' without spaces
+        'no_superfluous_phpdoc_tags' => ['allow_mixed' => true],
-        'not_operator_with_successor_space' => false, // idem
         'no_trailing_comma_in_list_call' => true,
         'no_trailing_comma_in_singleline_array' => true,
-        'no_trailing_whitespace_in_comment' => true,
         'no_trailing_whitespace' => true,
+        'no_trailing_whitespace_in_comment' => true,
         'no_unneeded_control_parentheses' => true,
         'no_unneeded_curly_braces' => true,
         'no_unneeded_final_method' => true,
         'no_unreachable_default_argument_value' => true,
+        'no_unset_cast' => true,
+        'no_unset_on_property' => true,
         'no_unused_imports' => true,
         'no_useless_else' => true,
         'no_useless_return' => true,
         'no_whitespace_before_comma_in_array' => true,
         'no_whitespace_in_blank_line' => true,
+        'non_printable_character' => true,
+        'normalize_index_brace' => true,
+        'not_operator_with_space' => false, // No we prefer to keep '!' without spaces
+        'not_operator_with_successor_space' => false, // idem
+        'nullable_type_declaration_for_default_null_value' => true,
         'object_operator_without_whitespace' => true,
         'ordered_class_elements' => false, // We prefer to keep some freedom
         'ordered_imports' => true,
+        'ordered_interfaces' => true,
+        'php_unit_construct' => true,
+        'php_unit_dedicate_assert' => true,
+        'php_unit_dedicate_assert_internal_type' => true,
+        'php_unit_expectation' => true,
+        'php_unit_fqcn_annotation' => true,
+        'php_unit_internal_class' => false, // Because tests are excluded from package
+        'php_unit_method_casing' => true,
+        'php_unit_mock' => true,
+        'php_unit_mock_short_will_return' => true,
+        'php_unit_namespaced' => true,
+        'php_unit_no_expectation_annotation' => true,
+        'php_unit_ordered_covers' => true,
+        'php_unit_set_up_tear_down_visibility' => true,
+        'php_unit_size_class' => false, // That seems extra work to maintain for little benefits
+        'php_unit_strict' => false, // We sometime actually need assertEquals
+        'php_unit_test_annotation' => true,
+        'php_unit_test_case_static_method_calls' => ['call_type' => 'self'],
+        'php_unit_test_class_requires_covers' => false, // We don't care as much as we should about coverage
         'phpdoc_add_missing_param_annotation' => true,
         'phpdoc_align' => false, // Waste of time
         'phpdoc_annotation_without_dot' => true,
         'phpdoc_indent' => true,
         'phpdoc_inline_tag' => true,
+        'phpdoc_line_span' => false, // Unfortunately our old comments turn even uglier with this
         'phpdoc_no_access' => true,
         'phpdoc_no_alias_tag' => true,
         'phpdoc_no_empty_return' => true,
@@ -132,43 +178,46 @@ return PhpCsFixer\Config::create()
         'phpdoc_single_line_var_spacing' => true,
         'phpdoc_summary' => true,
         'phpdoc_to_comment' => true,
+        'phpdoc_to_param_type' => false, // Because experimental, but interesting for one shot use
+        'phpdoc_to_return_type' => false, // idem
         'phpdoc_trim' => true,
-        'phpdoc_types_order' => true,
+        'phpdoc_trim_consecutive_blank_line_separation' => true,
         'phpdoc_types' => true,
+        'phpdoc_types_order' => true,
+        'phpdoc_var_annotation_correct_order' => true,
         'phpdoc_var_without_name' => true,
-        'php_unit_construct' => true,
+        'pow_to_exponentiation' => true,
-        'php_unit_dedicate_assert' => true,
+        'pre_increment' => false, // Deprecated
-        'php_unit_expectation' => true,
-        'php_unit_fqcn_annotation' => true,
-        'php_unit_mock' => true,
-        'php_unit_namespaced' => true,
-        'php_unit_no_expectation_annotation' => true,
-        'php_unit_strict' => false, // We sometime actually need assertEquals
-        'php_unit_test_annotation' => true,
-        'php_unit_test_class_requires_covers' => false, // We don't care as much as we should about coverage
-        'pow_to_exponentiation' => false,
         'protected_to_private' => true,
         'psr0' => true,
         'psr4' => true,
-        'random_api_migration' => false, // This breaks our unit tests
+        'random_api_migration' => true,
+        'return_assignment' => false, // Sometimes useful for clarity or debug
         'return_type_declaration' => true,
         'self_accessor' => true,
+        'self_static_accessor' => true,
         'semicolon_after_instruction' => false, // Buggy in `samples/index.php`
+        'set_type_to_cast' => true,
         'short_scalar_cast' => true,
-        'silenced_deprecation_error' => true,
+        'silenced_deprecation_error' => false, // Deprecated
-        'simplified_null_return' => false, // While technically correct we prefer to be explicit when returning null
+        'simple_to_complex_string_variable' => false, // Would differ from TypeScript without obvious advantages
+        'simplified_null_return' => false, // Even if technically correct we prefer to be explicit
         'single_blank_line_at_eof' => true,
         'single_blank_line_before_namespace' => true,
         'single_class_element_per_statement' => true,
         'single_import_per_statement' => true,
         'single_line_after_imports' => true,
         'single_line_comment_style' => true,
+        'single_line_throw' => false, // I don't see any reason for having a special case for Exception
         'single_quote' => true,
+        'single_trait_insert_per_statement' => true,
         'space_after_semicolon' => true,
+        'standardize_increment' => true,
         'standardize_not_equals' => true,
         'static_lambda' => false, // Risky if we can't guarantee nobody use `bindTo()`
         'strict_comparison' => false, // No, too dangerous to change that
         'strict_param' => false, // No, too dangerous to change that
+        'string_line_ending' => true,
         'switch_case_semicolon_to_colon' => true,
         'switch_case_space' => true,
         'ternary_operator_spaces' => true,
@@ -177,7 +226,7 @@ return PhpCsFixer\Config::create()
         'trim_array_spaces' => true,
         'unary_operator_spaces' => true,
         'visibility_required' => true,
-        'void_return' => false, // Cannot use that with PHP 5.6
+        'void_return' => true,
         'whitespace_after_comma_in_array' => true,
         'yoda_style' => false,
     ]);

samples/Autofilter/10_Autofilter_selection_1.php

@@ -59,18 +59,18 @@ foreach ($years as $year) {
                     $period,
                     $i
                 );
-                $value = rand(500, 1000) * (1 + (rand(-1, 1) / 4));
+                $value = mt_rand(500, 1000) * (1 + (mt_rand(-1, 1) / 4));
                 $salesValue = $invoiceValue = null;
-                $incomeOrExpenditure = rand(-1, 1);
+                $incomeOrExpenditure = mt_rand(-1, 1);
                 if ($incomeOrExpenditure == -1) {
-                    $expenditure = rand(-500, -1000) * (1 + (rand(-1, 1) / 4));
+                    $expenditure = mt_rand(-1000, -500) * (1 + (mt_rand(-1, 1) / 4));
                     $income = null;
                 } elseif ($incomeOrExpenditure == 1) {
-                    $expenditure = rand(-500, -1000) * (1 + (rand(-1, 1) / 4));
+                    $expenditure = mt_rand(-1000, -500) * (1 + (mt_rand(-1, 1) / 4));
-                    $income = rand(500, 1000) * (1 + (rand(-1, 1) / 4));
+                    $income = mt_rand(500, 1000) * (1 + (mt_rand(-1, 1) / 4));
                 } else {
                     $expenditure = null;
-                    $income = rand(500, 1000) * (1 + (rand(-1, 1) / 4));
+                    $income = mt_rand(500, 1000) * (1 + (mt_rand(-1, 1) / 4));
                 }
                 $dataArray = [$year,
                     $period,

samples/Autofilter/10_Autofilter_selection_2.php

@@ -59,18 +59,18 @@ foreach ($years as $year) {
                     $period,
                     $i
                 );
-                $value = rand(500, 1000) * (1 + (rand(-1, 1) / 4));
+                $value = mt_rand(500, 1000) * (1 + (mt_rand(-1, 1) / 4));
                 $salesValue = $invoiceValue = null;
-                $incomeOrExpenditure = rand(-1, 1);
+                $incomeOrExpenditure = mt_rand(-1, 1);
                 if ($incomeOrExpenditure == -1) {
-                    $expenditure = rand(-500, -1000) * (1 + (rand(-1, 1) / 4));
+                    $expenditure = mt_rand(-1000, -500) * (1 + (mt_rand(-1, 1) / 4));
                     $income = null;
                 } elseif ($incomeOrExpenditure == 1) {
-                    $expenditure = rand(-500, -1000) * (1 + (rand(-1, 1) / 4));
+                    $expenditure = mt_rand(-1000, -500) * (1 + (mt_rand(-1, 1) / 4));
-                    $income = rand(500, 1000) * (1 + (rand(-1, 1) / 4));
+                    $income = mt_rand(500, 1000) * (1 + (mt_rand(-1, 1) / 4));
                 } else {
                     $expenditure = null;
-                    $income = rand(500, 1000) * (1 + (rand(-1, 1) / 4));
+                    $income = mt_rand(500, 1000) * (1 + (mt_rand(-1, 1) / 4));
                 }
                 $dataArray = [$year,
                     $period,

samples/Autofilter/10_Autofilter_selection_display.php

@@ -59,18 +59,18 @@ foreach ($years as $year) {
                     $period,
                     $i
                 );
-                $value = rand(500, 1000) * (1 + (rand(-1, 1) / 4));
+                $value = mt_rand(500, 1000) * (1 + (mt_rand(-1, 1) / 4));
                 $salesValue = $invoiceValue = null;
-                $incomeOrExpenditure = rand(-1, 1);
+                $incomeOrExpenditure = mt_rand(-1, 1);
                 if ($incomeOrExpenditure == -1) {
-                    $expenditure = rand(-500, -1000) * (1 + (rand(-1, 1) / 4));
+                    $expenditure = mt_rand(-1000, -500) * (1 + (mt_rand(-1, 1) / 4));
                     $income = null;
                 } elseif ($incomeOrExpenditure == 1) {
-                    $expenditure = rand(-500, -1000) * (1 + (rand(-1, 1) / 4));
+                    $expenditure = mt_rand(-1000, -500) * (1 + (mt_rand(-1, 1) / 4));
-                    $income = rand(500, 1000) * (1 + (rand(-1, 1) / 4));
+                    $income = mt_rand(500, 1000) * (1 + (mt_rand(-1, 1) / 4));
                 } else {
                     $expenditure = null;
-                    $income = rand(500, 1000) * (1 + (rand(-1, 1) / 4));
+                    $income = mt_rand(500, 1000) * (1 + (mt_rand(-1, 1) / 4));
                 }
                 $dataArray = [$year,
                     $period,

samples/Basic/25_In_memory_image.php

@@ -21,7 +21,11 @@ $spreadsheet->getProperties()->setCreator('Maarten Balliauw')
 
 // Generate an image
 $helper->log('Generate an image');
-$gdImage = @imagecreatetruecolor(120, 20) or die('Cannot Initialize new GD image stream');
+$gdImage = @imagecreatetruecolor(120, 20);
+if (!$gdImage) {
+    die('Cannot Initialize new GD image stream');
+}
+
 $textColor = imagecolorallocate($gdImage, 255, 255, 255);
 imagestring($gdImage, 1, 5, 5, 'Created with PhpSpreadsheet', $textColor);
 

samples/Reader/12_Reading_a_workbook_in_chunks_using_a_configurable_read_filter_(version_2).php

@@ -23,7 +23,7 @@ class ChunkReadFilter implements IReadFilter
      * @param mixed $startRow
      * @param mixed $chunkSize
      */
-    public function setRows($startRow, $chunkSize)
+    public function setRows($startRow, $chunkSize): void
     {
         $this->startRow = $startRow;
         $this->endRow = $startRow + $chunkSize;

samples/Reader/14_Reading_a_large_CSV_file_in_chunks_to_split_across_multiple_worksheets.php

@@ -24,7 +24,7 @@ class ChunkReadFilter implements IReadFilter
      * @param mixed $startRow
      * @param mixed $chunkSize
      */
-    public function setRows($startRow, $chunkSize)
+    public function setRows($startRow, $chunkSize): void
     {
         $this->startRow = $startRow;
         $this->endRow = $startRow + $chunkSize;

src/PhpSpreadsheet/Calculation/Calculation.php

@@ -11,6 +11,7 @@ use PhpOffice\PhpSpreadsheet\NamedRange;
 use PhpOffice\PhpSpreadsheet\Shared;
 use PhpOffice\PhpSpreadsheet\Spreadsheet;
 use PhpOffice\PhpSpreadsheet\Worksheet\Worksheet;
+use ReflectionMethod;
 
 class Calculation
 {
@@ -2263,16 +2264,16 @@ class Calculation
         ],
     ];
 
-    public function __construct(Spreadsheet $spreadsheet = null)
+    public function __construct(?Spreadsheet $spreadsheet = null)
     {
-        $this->delta = 1 * pow(10, 0 - ini_get('precision'));
+        $this->delta = 1 * 10 ** (0 - ini_get('precision'));
 
         $this->spreadsheet = $spreadsheet;
         $this->cyclicReferenceStack = new CyclicReferenceStack();
         $this->debugLog = new Logger($this->cyclicReferenceStack);
     }
 
-    private static function loadLocales()
+    private static function loadLocales(): void
     {
         $localeFileDirectory = __DIR__ . '/locale/';
         foreach (glob($localeFileDirectory . '*', GLOB_ONLYDIR) as $filename) {
@@ -2291,7 +2292,7 @@ class Calculation
      *
      * @return Calculation
      */
-    public static function getInstance(Spreadsheet $spreadsheet = null)
+    public static function getInstance(?Spreadsheet $spreadsheet = null)
     {
         if ($spreadsheet !== null) {
             $instance = $spreadsheet->getCalculationEngine();
@@ -2311,7 +2312,7 @@ class Calculation
      * Flush the calculation cache for any existing instance of this class
      *        but only if a Calculation instance exists.
      */
-    public function flushInstance()
+    public function flushInstance(): void
     {
         $this->clearCalculationCache();
         $this->clearBranchStore();
@@ -2400,7 +2401,7 @@ class Calculation
      *
      * @param bool $pValue
      */
-    public function setCalculationCacheEnabled($pValue)
+    public function setCalculationCacheEnabled($pValue): void
     {
         $this->calculationCacheEnabled = $pValue;
         $this->clearCalculationCache();
@@ -2409,7 +2410,7 @@ class Calculation
     /**
      * Enable calculation cache.
      */
-    public function enableCalculationCache()
+    public function enableCalculationCache(): void
     {
         $this->setCalculationCacheEnabled(true);
     }
@@ -2417,7 +2418,7 @@ class Calculation
     /**
      * Disable calculation cache.
      */
-    public function disableCalculationCache()
+    public function disableCalculationCache(): void
     {
         $this->setCalculationCacheEnabled(false);
     }
@@ -2425,7 +2426,7 @@ class Calculation
     /**
      * Clear calculation cache.
      */
-    public function clearCalculationCache()
+    public function clearCalculationCache(): void
     {
         $this->calculationCache = [];
     }
@@ -2435,7 +2436,7 @@ class Calculation
      *
      * @param string $worksheetName
      */
-    public function clearCalculationCacheForWorksheet($worksheetName)
+    public function clearCalculationCacheForWorksheet($worksheetName): void
     {
         if (isset($this->calculationCache[$worksheetName])) {
             unset($this->calculationCache[$worksheetName]);
@@ -2448,7 +2449,7 @@ class Calculation
      * @param string $fromWorksheetName
      * @param string $toWorksheetName
      */
-    public function renameCalculationCacheForWorksheet($fromWorksheetName, $toWorksheetName)
+    public function renameCalculationCacheForWorksheet($fromWorksheetName, $toWorksheetName): void
     {
         if (isset($this->calculationCache[$fromWorksheetName])) {
             $this->calculationCache[$toWorksheetName] = &$this->calculationCache[$fromWorksheetName];
@@ -2459,25 +2460,24 @@ class Calculation
     /**
      * Enable/disable calculation cache.
      *
-     * @param bool $pValue
      * @param mixed $enabled
      */
-    public function setBranchPruningEnabled($enabled)
+    public function setBranchPruningEnabled($enabled): void
     {
         $this->branchPruningEnabled = $enabled;
     }
 
-    public function enableBranchPruning()
+    public function enableBranchPruning(): void
     {
         $this->setBranchPruningEnabled(true);
     }
 
-    public function disableBranchPruning()
+    public function disableBranchPruning(): void
     {
         $this->setBranchPruningEnabled(false);
     }
 
-    public function clearBranchStore()
+    public function clearBranchStore(): void
     {
         $this->branchStoreKeyCounter = 0;
     }
@@ -2779,7 +2779,7 @@ class Calculation
      *
      * @return mixed
      */
-    public function calculate(Cell $pCell = null)
+    public function calculate(?Cell $pCell = null)
     {
         try {
             return $this->calculateCellValue($pCell);
@@ -2796,7 +2796,7 @@ class Calculation
      *
      * @return mixed
      */
-    public function calculateCellValue(Cell $pCell = null, $resetLog = true)
+    public function calculateCellValue(?Cell $pCell = null, $resetLog = true)
     {
         if ($pCell === null) {
             return null;
@@ -2898,7 +2898,7 @@ class Calculation
      *
      * @return mixed
      */
-    public function calculateFormula($formula, $cellID = null, Cell $pCell = null)
+    public function calculateFormula($formula, $cellID = null, ?Cell $pCell = null)
     {
         //    Initialise the logging settings
         $this->formulaError = null;
@@ -2957,7 +2957,7 @@ class Calculation
      * @param string $cellReference
      * @param mixed $cellValue
      */
-    public function saveValueToCache($cellReference, $cellValue)
+    public function saveValueToCache($cellReference, $cellValue): void
     {
         if ($this->calculationCacheEnabled) {
             $this->calculationCache[$cellReference] = $cellValue;
@@ -2973,7 +2973,7 @@ class Calculation
      *
      * @return mixed
      */
-    public function _calculateFormulaValue($formula, $cellID = null, Cell $pCell = null)
+    public function _calculateFormulaValue($formula, $cellID = null, ?Cell $pCell = null)
     {
         $cellValue = null;
 
@@ -3119,7 +3119,7 @@ class Calculation
      * @param int $matrix2Rows Row size of second matrix operand
      * @param int $matrix2Columns Column size of second matrix operand
      */
-    private static function resizeMatricesShrink(&$matrix1, &$matrix2, $matrix1Rows, $matrix1Columns, $matrix2Rows, $matrix2Columns)
+    private static function resizeMatricesShrink(&$matrix1, &$matrix2, $matrix1Rows, $matrix1Columns, $matrix2Rows, $matrix2Columns): void
     {
         if (($matrix2Columns < $matrix1Columns) || ($matrix2Rows < $matrix1Rows)) {
             if ($matrix2Rows < $matrix1Rows) {
@@ -3162,7 +3162,7 @@ class Calculation
      * @param int $matrix2Rows Row size of second matrix operand
      * @param int $matrix2Columns Column size of second matrix operand
      */
-    private static function resizeMatricesExtend(&$matrix1, &$matrix2, $matrix1Rows, $matrix1Columns, $matrix2Rows, $matrix2Columns)
+    private static function resizeMatricesExtend(&$matrix1, &$matrix2, $matrix1Rows, $matrix1Columns, $matrix2Rows, $matrix2Columns): void
     {
         if (($matrix2Columns < $matrix1Columns) || ($matrix2Rows < $matrix1Rows)) {
             if ($matrix2Columns < $matrix1Columns) {
@@ -3371,11 +3371,10 @@ class Calculation
 
     /**
      * @param string $formula
-     * @param null|\PhpOffice\PhpSpreadsheet\Cell\Cell $pCell
      *
      * @return bool
      */
-    private function _parseFormula($formula, Cell $pCell = null)
+    private function _parseFormula($formula, ?Cell $pCell = null)
     {
         if (($formula = $this->convertMatrixReferences(trim($formula))) === false) {
             return false;
@@ -3469,7 +3468,7 @@ class Calculation
                 ++$index; //    Drop the redundant plus symbol
             } elseif ((($opCharacter == '~') || ($opCharacter == '|')) && (!$isOperandOrFunction)) {    //    We have to explicitly deny a tilde or pipe, because they are legal
                 return $this->raiseFormulaError("Formula Error: Illegal character '~'"); //        on the stack but not in the input expression
-            } elseif ((isset(self::$operators[$opCharacter]) or $isOperandOrFunction) && $expectingOperator) {    //    Are we putting an operator on the stack?
+            } elseif ((isset(self::$operators[$opCharacter]) || $isOperandOrFunction) && $expectingOperator) {    //    Are we putting an operator on the stack?
                 while ($stack->count() > 0 &&
                     ($o2 = $stack->last()) &&
                     isset(self::$operators[$o2['value']]) &&
@@ -3495,7 +3494,7 @@ class Calculation
                 // Branch pruning we decrease the depth whether is it a function
                 // call or a parenthesis
                 if (!empty($pendingStoreKey)) {
-                    $parenthesisDepthMap[$pendingStoreKey] -= 1;
+                    --$parenthesisDepthMap[$pendingStoreKey];
                 }
 
                 if (is_array($d) && preg_match('/^' . self::CALCULATION_REGEXP_FUNCTION . '$/i', $d['value'], $matches)) {    //    Did this parenthesis just close a function?
@@ -3509,7 +3508,7 @@ class Calculation
                         }
                         $expectingThenMap[$pendingStoreKey] = false;
                         $expectingElseMap[$pendingStoreKey] = false;
-                        $parenthesisDepthMap[$pendingStoreKey] -= 1;
+                        --$parenthesisDepthMap[$pendingStoreKey];
                         array_pop($pendingStoreKeysStack);
                         unset($pendingStoreKey);
                     }
@@ -3615,7 +3614,7 @@ class Calculation
                 ++$index;
             } elseif ($opCharacter == '(' && !$expectingOperator) {
                 if (!empty($pendingStoreKey)) { // Branch pruning: we go deeper
-                    $parenthesisDepthMap[$pendingStoreKey] += 1;
+                    ++$parenthesisDepthMap[$pendingStoreKey];
                 }
                 $stack->push('Brace', '(', null, $currentCondition, $currentOnlyIf, $currentOnlyIf);
                 ++$index;
@@ -3641,7 +3640,7 @@ class Calculation
                         $parenthesisDepthMap[$pendingStoreKey] = 0;
                     } else { // this is not an if but we go deeper
                         if (!empty($pendingStoreKey) && array_key_exists($pendingStoreKey, $parenthesisDepthMap)) {
-                            $parenthesisDepthMap[$pendingStoreKey] += 1;
+                            ++$parenthesisDepthMap[$pendingStoreKey];
                         }
                     }
 
@@ -3818,11 +3817,10 @@ class Calculation
     /**
      * @param mixed $tokens
      * @param null|string $cellID
-     * @param null|Cell $pCell
      *
      * @return bool
      */
-    private function processTokenStack($tokens, $cellID = null, Cell $pCell = null)
+    private function processTokenStack($tokens, $cellID = null, ?Cell $pCell = null)
     {
         if ($tokens == false) {
             return false;
@@ -4361,7 +4359,6 @@ class Calculation
      * @param mixed $operand1
      * @param mixed $operand2
      * @param string $operation
-     * @param Stack $stack
      * @param bool $recursingArrays
      *
      * @return mixed
@@ -4583,7 +4580,7 @@ class Calculation
                         break;
                     //    Power
                     case '^':
-                        $result = pow($operand1, $operand2);
+                        $result = $operand1 ** $operand2;
 
                         break;
                 }
@@ -4620,7 +4617,7 @@ class Calculation
      *
      * @return mixed Array of values in range if range contains more than one element. Otherwise, a single value is returned.
      */
-    public function extractCellRange(&$pRange = 'A1', Worksheet $pSheet = null, $resetLog = true)
+    public function extractCellRange(&$pRange = 'A1', ?Worksheet $pSheet = null, $resetLog = true)
     {
         // Return value
         $returnValue = [];
@@ -4673,7 +4670,7 @@ class Calculation
      *
      * @return mixed Array of values in range if range contains more than one element. Otherwise, a single value is returned.
      */
-    public function extractNamedRange(&$pRange = 'A1', Worksheet $pSheet = null, $resetLog = true)
+    public function extractNamedRange(&$pRange = 'A1', ?Worksheet $pSheet = null, $resetLog = true)
     {
         // Return value
         $returnValue = [];
@@ -4773,21 +4770,19 @@ class Calculation
     /**
      * Add cell reference if needed while making sure that it is the last argument.
      *
-     * @param array $args
      * @param bool $passCellReference
      * @param array|string $functionCall
-     * @param null|Cell $pCell
      *
      * @return array
      */
-    private function addCellReference(array $args, $passCellReference, $functionCall, Cell $pCell = null)
+    private function addCellReference(array $args, $passCellReference, $functionCall, ?Cell $pCell = null)
     {
         if ($passCellReference) {
             if (is_array($functionCall)) {
                 $className = $functionCall[0];
                 $methodName = $functionCall[1];
 
-                $reflectionMethod = new \ReflectionMethod($className, $methodName);
+                $reflectionMethod = new ReflectionMethod($className, $methodName);
                 $argumentCount = count($reflectionMethod->getParameters());
                 while (count($args) < $argumentCount - 1) {
                     $args[] = null;

src/PhpSpreadsheet/Calculation/DateTime.php

@@ -2,6 +2,8 @@
 
 namespace PhpOffice\PhpSpreadsheet\Calculation;
 
+use DateTimeImmutable;
+use DateTimeInterface;
 use PhpOffice\PhpSpreadsheet\Shared\Date;
 use PhpOffice\PhpSpreadsheet\Shared\StringHelper;
 
@@ -66,7 +68,7 @@ class DateTime
     public static function getDateValue($dateValue)
     {
         if (!is_numeric($dateValue)) {
-            if ((is_object($dateValue)) && ($dateValue instanceof \DateTimeInterface)) {
+            if ((is_object($dateValue)) && ($dateValue instanceof DateTimeInterface)) {
                 $dateValue = Date::PHPToExcel($dateValue);
             } else {
                 $saveReturnDateType = Functions::getReturnDateType();
@@ -768,9 +770,9 @@ class DateTime
      *
      * @category Date/Time Functions
      *
-     * @param \DateTimeImmutable|float|int|string $endDate Excel date serial value (float),
+     * @param DateTimeImmutable|float|int|string $endDate Excel date serial value (float),
      * PHP date timestamp (integer), PHP DateTime object, or a standard date string
-     * @param \DateTimeImmutable|float|int|string $startDate Excel date serial value (float),
+     * @param DateTimeImmutable|float|int|string $startDate Excel date serial value (float),
      * PHP date timestamp (integer), PHP DateTime object, or a standard date string
      *
      * @return int|string Number of days between start date and end date or an error

src/PhpSpreadsheet/Calculation/Engine/CyclicReferenceStack.php

@@ -26,7 +26,7 @@ class CyclicReferenceStack
      *
      * @param mixed $value
      */
-    public function push($value)
+    public function push($value): void
     {
         $this->stack[$value] = $value;
     }
@@ -56,7 +56,7 @@ class CyclicReferenceStack
     /**
      * Clear the stack.
      */
-    public function clear()
+    public function clear(): void
     {
         $this->stack = [];
     }

src/PhpSpreadsheet/Calculation/Engine/Logger.php

@@ -39,8 +39,6 @@ class Logger
 
     /**
      * Instantiate a Calculation engine logger.
-     *
-     * @param CyclicReferenceStack $stack
      */
     public function __construct(CyclicReferenceStack $stack)
     {
@@ -52,7 +50,7 @@ class Logger
      *
      * @param bool $pValue
      */
-    public function setWriteDebugLog($pValue)
+    public function setWriteDebugLog($pValue): void
     {
         $this->writeDebugLog = $pValue;
     }
@@ -72,7 +70,7 @@ class Logger
      *
      * @param bool $pValue
      */
-    public function setEchoDebugLog($pValue)
+    public function setEchoDebugLog($pValue): void
     {
         $this->echoDebugLog = $pValue;
     }
@@ -90,11 +88,11 @@ class Logger
     /**
      * Write an entry to the calculation engine debug log.
      */
-    public function writeDebugLog(...$args)
+    public function writeDebugLog(...$args): void
     {
         //    Only write the debug log if logging is enabled
         if ($this->writeDebugLog) {
-            $message = implode($args);
+            $message = implode('', $args);
             $cellReference = implode(' -> ', $this->cellStack->showStack());
             if ($this->echoDebugLog) {
                 echo $cellReference,
@@ -111,7 +109,7 @@ class Logger
     /**
      * Clear the calculation engine debug log.
      */
-    public function clearLog()
+    public function clearLog(): void
     {
         $this->debugLog = [];
     }

src/PhpSpreadsheet/Calculation/Engineering.php

@@ -799,7 +799,7 @@ class Engineering
             }
 
             if (abs($x) <= 30) {
-                $fResult = $fTerm = pow($x / 2, $ord) / MathTrig::FACT($ord);
+                $fResult = $fTerm = ($x / 2) ** $ord / MathTrig::FACT($ord);
                 $ordK = 1;
                 $fSqrX = ($x * $x) / 4;
                 do {
@@ -854,7 +854,7 @@ class Engineering
 
             $fResult = 0;
             if (abs($x) <= 30) {
-                $fResult = $fTerm = pow($x / 2, $ord) / MathTrig::FACT($ord);
+                $fResult = $fTerm = ($x / 2) ** $ord / MathTrig::FACT($ord);
                 $ordK = 1;
                 $fSqrX = ($x * $x) / -4;
                 do {
@@ -2357,7 +2357,7 @@ class Engineering
         } elseif (is_numeric($value)) {
             if ($value == (int) ($value)) {
                 $value = (int) ($value);
-                if (($value > pow(2, 48) - 1) || ($value < 0)) {
+                if (($value > 2 ** 48 - 1) || ($value < 0)) {
                     throw new Exception(Functions::NAN());
                 }
 
@@ -2477,7 +2477,7 @@ class Engineering
         $shiftAmount = Functions::flattenSingleValue($shiftAmount);
 
         $result = $number << $shiftAmount;
-        if ($result > pow(2, 48) - 1) {
+        if ($result > 2 ** 48 - 1) {
             return Functions::NAN();
         }
 

src/PhpSpreadsheet/Calculation/Exception.php

@@ -15,7 +15,7 @@ class Exception extends PhpSpreadsheetException
      * @param mixed $line
      * @param mixed $context
      */
-    public static function errorHandlerCallback($code, $string, $file, $line, $context)
+    public static function errorHandlerCallback($code, $string, $file, $line, $context): void
     {
         $e = new self($string, $code);
         $e->line = $line;

src/PhpSpreadsheet/Calculation/Financial.php

@@ -851,7 +851,7 @@ class Financial
                 return Functions::NAN();
             }
             //    Set Fixed Depreciation Rate
-            $fixedDepreciationRate = 1 - pow(($salvage / $cost), (1 / $life));
+            $fixedDepreciationRate = 1 - ($salvage / $cost) ** (1 / $life);
             $fixedDepreciationRate = round($fixedDepreciationRate, 3);
 
             //    Loop through each period calculating the depreciation
@@ -917,7 +917,7 @@ class Financial
                 return Functions::NAN();
             }
             //    Set Fixed Depreciation Rate
-            $fixedDepreciationRate = 1 - pow(($salvage / $cost), (1 / $life));
+            $fixedDepreciationRate = 1 - ($salvage / $cost) ** (1 / $life);
             $fixedDepreciationRate = round($fixedDepreciationRate, 3);
 
             //    Loop through each period calculating the depreciation
@@ -1021,7 +1021,7 @@ class Financial
         $dollars = floor($fractional_dollar);
         $cents = fmod($fractional_dollar, 1);
         $cents /= $fraction;
-        $cents *= pow(10, ceil(log10($fraction)));
+        $cents *= 10 ** ceil(log10($fraction));
 
         return $dollars + $cents;
     }
@@ -1059,7 +1059,7 @@ class Financial
         $dollars = floor($decimal_dollar);
         $cents = fmod($decimal_dollar, 1);
         $cents *= $fraction;
-        $cents *= pow(10, -ceil(log10($fraction)));
+        $cents *= 10 ** (-ceil(log10($fraction)));
 
         return $dollars + $cents;
     }
@@ -1090,7 +1090,7 @@ class Financial
             return Functions::NAN();
         }
 
-        return pow((1 + $nominal_rate / $npery), $npery) - 1;
+        return (1 + $nominal_rate / $npery) ** $npery - 1;
     }
 
     /**
@@ -1131,7 +1131,7 @@ class Financial
 
         // Calculate
         if ($rate !== null && $rate != 0) {
-            return -$pv * pow(1 + $rate, $nper) - $pmt * (1 + $rate * $type) * (pow(1 + $rate, $nper) - 1) / $rate;
+            return -$pv * (1 + $rate) ** $nper - $pmt * (1 + $rate * $type) * ((1 + $rate) ** $nper - 1) / $rate;
         }
 
         return -$pv - $pmt * $nper;
@@ -1400,9 +1400,9 @@ class Financial
         $npv_pos = $npv_neg = 0.0;
         foreach ($values as $i => $v) {
             if ($v >= 0) {
-                $npv_pos += $v / pow($rr, $i);
+                $npv_pos += $v / $rr ** $i;
             } else {
-                $npv_neg += $v / pow($fr, $i);
+                $npv_neg += $v / $fr ** $i;
             }
         }
 
@@ -1410,8 +1410,8 @@ class Financial
             return Functions::VALUE();
         }
 
-        $mirr = pow((-$npv_pos * pow($rr, $n))
+        $mirr = ((-$npv_pos * $rr ** $n)
-                / ($npv_neg * ($rr)), (1.0 / ($n - 1))) - 1.0;
+                / ($npv_neg * ($rr))) ** (1.0 / ($n - 1)) - 1.0;
 
         return is_finite($mirr) ? $mirr : Functions::VALUE();
     }
@@ -1437,7 +1437,7 @@ class Financial
         }
 
         // Calculate
-        return $npery * (pow($effect_rate + 1, 1 / $npery) - 1);
+        return $npery * (($effect_rate + 1) ** (1 / $npery) - 1);
     }
 
     /**
@@ -1502,7 +1502,7 @@ class Financial
         for ($i = 1; $i <= $countArgs; ++$i) {
             // Is it a numeric value?
             if (is_numeric($aArgs[$i - 1])) {
-                $returnValue += $aArgs[$i - 1] / pow(1 + $rate, $i);
+                $returnValue += $aArgs[$i - 1] / (1 + $rate) ** $i;
             }
         }
 
@@ -1565,7 +1565,7 @@ class Financial
 
         // Calculate
         if ($rate !== null && $rate != 0) {
-            return (-$fv - $pv * pow(1 + $rate, $nper)) / (1 + $rate * $type) / ((pow(1 + $rate, $nper) - 1) / $rate);
+            return (-$fv - $pv * (1 + $rate) ** $nper) / (1 + $rate * $type) / (((1 + $rate) ** $nper - 1) / $rate);
         }
 
         return (-$pv - $fv) / $nper;
@@ -1672,9 +1672,9 @@ class Financial
         $rfp = 100 * ($rate / $frequency);
         $de = $dsc / $e;
 
-        $result = $redemption / pow($baseYF, (--$n + $de));
+        $result = $redemption / $baseYF ** (--$n + $de);
         for ($k = 0; $k <= $n; ++$k) {
-            $result += $rfp / (pow($baseYF, ($k + $de)));
+            $result += $rfp / ($baseYF ** ($k + $de));
         }
         $result -= $rfp * ($a / $e);
 
@@ -1820,7 +1820,7 @@ class Financial
 
         // Calculate
         if ($rate !== null && $rate != 0) {
-            return (-$pmt * (1 + $rate * $type) * ((pow(1 + $rate, $nper) - 1) / $rate) - $fv) / pow(1 + $rate, $nper);
+            return (-$pmt * (1 + $rate * $type) * (((1 + $rate) ** $nper - 1) / $rate) - $fv) / (1 + $rate) ** $nper;
         }
 
         return -$fv - $pmt * $nper;
@@ -1889,8 +1889,8 @@ class Financial
         if ($rate == 0) {
             return Functions::NAN();
         }
-        $tt1 = pow($rate + 1, $nper);
+        $tt1 = ($rate + 1) ** $nper;
-        $tt2 = pow($rate + 1, $nper - 1);
+        $tt2 = ($rate + 1) ** ($nper - 1);
         $numerator = $fv + $tt1 * $pv + $pmt * ($tt1 - 1) * ($rate * $type + 1) / $rate;
         $denominator = $nper * $tt2 * $pv - $pmt * ($tt1 - 1) * ($rate * $type + 1) / ($rate * $rate)
              + $nper * $pmt * $tt2 * ($rate * $type + 1) / $rate
@@ -1971,7 +1971,7 @@ class Financial
             return Functions::NAN();
         }
 
-        return pow($fv / $pv, 1 / $nper) - 1;
+        return ($fv / $pv) ** (1 / $nper) - 1;
     }
 
     /**
@@ -2377,7 +2377,7 @@ class Financial
             if (!is_numeric($dif)) {
                 return $dif;
             }
-            $xnpv += $values[$i] / pow(1 + $rate, $dif / 365);
+            $xnpv += $values[$i] / (1 + $rate) ** ($dif / 365);
         }
 
         return is_finite($xnpv) ? $xnpv : Functions::VALUE();

src/PhpSpreadsheet/Calculation/FormulaParser.php

@@ -125,7 +125,7 @@ class FormulaParser
     /**
      * Parse to tokens.
      */
-    private function parseToTokens()
+    private function parseToTokens(): void
     {
         // No attempt is made to verify formulas; assumes formulas are derived from Excel, where
         // they can only exist if valid; stack overflows/underflows sunk as nulls without exceptions.

src/PhpSpreadsheet/Calculation/FormulaToken.php

@@ -103,7 +103,7 @@ class FormulaToken
      *
      * @param string $value
      */
-    public function setValue($value)
+    public function setValue($value): void
     {
         $this->value = $value;
     }
@@ -123,7 +123,7 @@ class FormulaToken
      *
      * @param string $value
      */
-    public function setTokenType($value)
+    public function setTokenType($value): void
     {
         $this->tokenType = $value;
     }
@@ -143,7 +143,7 @@ class FormulaToken
      *
      * @param string $value
      */
-    public function setTokenSubType($value)
+    public function setTokenSubType($value): void
     {
         $this->tokenSubType = $value;
     }

src/PhpSpreadsheet/Calculation/Functions.php

@@ -660,7 +660,7 @@ class Functions
      *
      * @return bool|string
      */
-    public static function isFormula($cellReference = '', Cell $pCell = null)
+    public static function isFormula($cellReference = '', ?Cell $pCell = null)
     {
         if ($pCell === null) {
             return self::REF();

src/PhpSpreadsheet/Calculation/LookupRef.php

@@ -238,7 +238,7 @@ class LookupRef
      *
      * @return mixed The value of $displayName (or $linkURL if $displayName was blank)
      */
-    public static function HYPERLINK($linkURL = '', $displayName = null, Cell $pCell = null)
+    public static function HYPERLINK($linkURL = '', $displayName = null, ?Cell $pCell = null)
     {
         $linkURL = ($linkURL === null) ? '' : Functions::flattenSingleValue($linkURL);
         $displayName = ($displayName === null) ? '' : Functions::flattenSingleValue($displayName);
@@ -275,7 +275,7 @@ class LookupRef
      *
      * @todo    Support for the optional a1 parameter introduced in Excel 2010
      */
-    public static function INDIRECT($cellAddress = null, Cell $pCell = null)
+    public static function INDIRECT($cellAddress = null, ?Cell $pCell = null)
     {
         $cellAddress = Functions::flattenSingleValue($cellAddress);
         if ($cellAddress === null || $cellAddress === '') {
@@ -339,11 +339,10 @@ class LookupRef
      *                                starting reference).
      * @param mixed $height The height, in number of rows, that you want the returned reference to be. Height must be a positive number.
      * @param mixed $width The width, in number of columns, that you want the returned reference to be. Width must be a positive number.
-     * @param null|Cell $pCell
      *
      * @return string A reference to a cell or range of cells
      */
-    public static function OFFSET($cellAddress = null, $rows = 0, $columns = 0, $height = null, $width = null, Cell $pCell = null)
+    public static function OFFSET($cellAddress = null, $rows = 0, $columns = 0, $height = null, $width = null, ?Cell $pCell = null)
     {
         $rows = Functions::flattenSingleValue($rows);
         $columns = Functions::flattenSingleValue($columns);
@@ -419,14 +418,6 @@ class LookupRef
      * Excel Function:
      *        =CHOOSE(index_num, value1, [value2], ...)
      *
-     * @param mixed $index_num Specifies which value argument is selected.
-     *                            Index_num must be a number between 1 and 254, or a formula or reference to a cell containing a number
-     *                                between 1 and 254.
-     * @param mixed $value1 ... Value1 is required, subsequent values are optional.
-     *                            Between 1 to 254 value arguments from which CHOOSE selects a value or an action to perform based on
-     *                                index_num. The arguments can be numbers, cell references, defined names, formulas, functions, or
-     *                                text.
-     *
      * @return mixed The selected value
      */
     public static function CHOOSE(...$chooseArgs)
@@ -945,7 +936,7 @@ class LookupRef
      *
      * @return string
      */
-    public static function FORMULATEXT($cellReference = '', Cell $pCell = null)
+    public static function FORMULATEXT($cellReference = '', ?Cell $pCell = null)
     {
         if ($pCell === null) {
             return Functions::REF();

src/PhpSpreadsheet/Calculation/MathTrig.php

@@ -2,6 +2,7 @@
 
 namespace PhpOffice\PhpSpreadsheet\Calculation;
 
+use Exception;
 use Matrix\Exception as MatrixException;
 use Matrix\Matrix;
 
@@ -68,7 +69,7 @@ class MathTrig
 
         try {
             $arabic = self::calculateArabic(str_split($roman));
-        } catch (\Exception $e) {
+        } catch (Exception $e) {
             return Functions::VALUE(); // Invalid character detected
         }
 
@@ -82,7 +83,6 @@ class MathTrig
     /**
      * Recursively calculate the arabic value of a roman numeral.
      *
-     * @param array $roman
      * @param int $sum
      * @param int $subtract
      *
@@ -102,7 +102,7 @@ class MathTrig
 
         $numeral = array_shift($roman);
         if (!isset($lookup[$numeral])) {
-            throw new \Exception('Invalid character detected');
+            throw new Exception('Invalid character detected');
         }
 
         $arabic = $lookup[$numeral];
@@ -618,7 +618,7 @@ class MathTrig
             $myCountedFactors = array_count_values($myFactors);
             $myPoweredFactors = [];
             foreach ($myCountedFactors as $myCountedFactor => $myCountedPower) {
-                $myPoweredFactors[$myCountedFactor] = pow($myCountedFactor, $myCountedPower);
+                $myPoweredFactors[$myCountedFactor] = $myCountedFactor ** $myCountedPower;
             }
             foreach ($myPoweredFactors as $myPoweredValue => $myPoweredFactor) {
                 if (isset($allPoweredFactors[$myPoweredValue])) {
@@ -986,7 +986,7 @@ class MathTrig
         }
 
         // Return
-        $result = pow($x, $y);
+        $result = $x ** $y;
 
         return (!is_nan($result) && !is_infinite($result)) ? $result : Functions::NAN();
     }
@@ -1139,10 +1139,10 @@ class MathTrig
 
         if ((is_numeric($number)) && (is_numeric($digits))) {
             if ($number < 0.0) {
-                return round($number - 0.5 * pow(0.1, $digits), $digits, PHP_ROUND_HALF_DOWN);
+                return round($number - 0.5 * 0.1 ** $digits, $digits, PHP_ROUND_HALF_DOWN);
             }
 
-            return round($number + 0.5 * pow(0.1, $digits), $digits, PHP_ROUND_HALF_DOWN);
+            return round($number + 0.5 * 0.1 ** $digits, $digits, PHP_ROUND_HALF_DOWN);
         }
 
         return Functions::VALUE();
@@ -1165,10 +1165,10 @@ class MathTrig
 
         if ((is_numeric($number)) && (is_numeric($digits))) {
             if ($number < 0.0) {
-                return round($number + 0.5 * pow(0.1, $digits), $digits, PHP_ROUND_HALF_UP);
+                return round($number + 0.5 * 0.1 ** $digits, $digits, PHP_ROUND_HALF_UP);
             }
 
-            return round($number - 0.5 * pow(0.1, $digits), $digits, PHP_ROUND_HALF_UP);
+            return round($number - 0.5 * 0.1 ** $digits, $digits, PHP_ROUND_HALF_UP);
         }
 
         return Functions::VALUE();
@@ -1179,9 +1179,6 @@ class MathTrig
      *
      * Returns the sum of a power series
      *
-     * @param float $x Input value to the power series
-     * @param float $n Initial power to which you want to raise $x
-     * @param float $m Step by which to increase $n for each term in the series
      * @param array of mixed Data Series
      *
      * @return float|string The result, or a string containing an error
@@ -1203,7 +1200,7 @@ class MathTrig
             foreach ($aArgs as $arg) {
                 // Is it a numeric value?
                 if ((is_numeric($arg)) && (!is_string($arg))) {
-                    $returnValue += $arg * pow($x, $n + ($m * $i++));
+                    $returnValue += $arg * $x ** ($n + ($m * $i++));
                 } else {
                     return Functions::VALUE();
                 }
@@ -1445,7 +1442,6 @@ class MathTrig
      *    @category Mathematical and Trigonometric Functions
      *
      * @param mixed $args Data values
-     * @param string $condition the criteria that defines which cells will be summed
      *
      * @return float
      */
@@ -1663,7 +1659,7 @@ class MathTrig
         $digits = floor($digits);
 
         // Truncate
-        $adjust = pow(10, $digits);
+        $adjust = 10 ** $digits;
 
         if (($digits > 0) && (rtrim((int) ((abs($value) - abs((int) $value)) * $adjust), '0') < $adjust / 10)) {
             return $value;

src/PhpSpreadsheet/Calculation/Statistical.php

@@ -397,10 +397,10 @@ class Statistical
             for ($i = 1; $i <= $n; ++$i) {
                 $divisor *= ($a + $i);
             }
-            $summer += (pow($x, $n) / $divisor);
+            $summer += ($x ** $n / $divisor);
         }
 
-        return pow($x, $a) * exp(0 - $x) * $summer;
+        return $x ** $a * exp(0 - $x) * $summer;
     }
 
     //
@@ -874,13 +874,13 @@ class Statistical
                 if ($cumulative) {
                     $summer = 0;
                     for ($i = 0; $i <= $value; ++$i) {
-                        $summer += MathTrig::COMBIN($trials, $i) * pow($probability, $i) * pow(1 - $probability, $trials - $i);
+                        $summer += MathTrig::COMBIN($trials, $i) * $probability ** $i * (1 - $probability) ** ($trials - $i);
                     }
 
                     return $summer;
                 }
 
-                return MathTrig::COMBIN($trials, $value) * pow($probability, $value) * pow(1 - $probability, $trials - $value);
+                return MathTrig::COMBIN($trials, $value) * $probability ** $value * (1 - $probability) ** ($trials - $value);
             }
         }
 
@@ -1320,7 +1320,7 @@ class Statistical
                 $t = sqrt(log(1 / ($alpha * $alpha)));
                 $trialsApprox = 0 - ($t + (2.515517 + 0.802853 * $t + 0.010328 * $t * $t) / (1 + 1.432788 * $t + 0.189269 * $t * $t + 0.001308 * $t * $t * $t));
             } else {
-                $t = sqrt(log(1 / pow(1 - $alpha, 2)));
+                $t = sqrt(log(1 / (1 - $alpha) ** 2));
                 $trialsApprox = $t - (2.515517 + 0.802853 * $t + 0.010328 * $t * $t) / (1 + 1.432788 * $t + 0.189269 * $t * $t + 0.001308 * $t * $t * $t);
             }
 
@@ -1441,9 +1441,9 @@ class Statistical
                 }
                 if ((is_numeric($arg)) && (!is_string($arg))) {
                     if ($returnValue === null) {
-                        $returnValue = pow(($arg - $aMean), 2);
+                        $returnValue = ($arg - $aMean) ** 2;
                     } else {
-                        $returnValue += pow(($arg - $aMean), 2);
+                        $returnValue += ($arg - $aMean) ** 2;
                     }
                     ++$aCount;
                 }
@@ -1603,7 +1603,7 @@ class Statistical
                     return self::incompleteGamma($a, $value / $b) / self::gamma($a);
                 }
 
-                return (1 / (pow($b, $a) * self::gamma($a))) * pow($value, $a - 1) * exp(0 - ($value / $b));
+                return (1 / ($b ** $a * self::gamma($a))) * $value ** ($a - 1) * exp(0 - ($value / $b));
             }
         }
 
@@ -1721,7 +1721,7 @@ class Statistical
         if (is_numeric($aMean) && ($aMean > 0)) {
             $aCount = self::COUNT($aArgs);
             if (self::MIN($aArgs) > 0) {
-                return pow($aMean, (1 / $aCount));
+                return $aMean ** (1 / $aCount);
             }
         }
 
@@ -1900,7 +1900,7 @@ class Statistical
                 } else {
                     // Is it a numeric value?
                     if ((is_numeric($arg)) && (!is_string($arg))) {
-                        $summer += pow((($arg - $mean) / $stdDev), 4);
+                        $summer += (($arg - $mean) / $stdDev) ** 4;
                         ++$count;
                     }
                 }
@@ -1908,7 +1908,7 @@ class Statistical
 
             // Return
             if ($count > 3) {
-                return $summer * ($count * ($count + 1) / (($count - 1) * ($count - 2) * ($count - 3))) - (3 * pow($count - 1, 2) / (($count - 2) * ($count - 3)));
+                return $summer * ($count * ($count + 1) / (($count - 1) * ($count - 2) * ($count - 3))) - (3 * ($count - 1) ** 2 / (($count - 2) * ($count - 3)));
             }
         }
 
@@ -1927,7 +1927,6 @@ class Statistical
      * @category Statistical Functions
      *
      * @param mixed $args Data values
-     * @param int $entry Position (ordered from the largest) in the array or range of data to return
      *
      * @return float|string The result, or a string containing an error
      */
@@ -2579,7 +2578,7 @@ class Statistical
                 }
             }
 
-            return (MathTrig::COMBIN($failures + $successes - 1, $successes - 1)) * (pow($probability, $successes)) * (pow(1 - $probability, $failures));
+            return (MathTrig::COMBIN($failures + $successes - 1, $successes - 1)) * ($probability ** $successes) * ((1 - $probability) ** $failures);
         }
 
         return Functions::VALUE();
@@ -2614,7 +2613,7 @@ class Statistical
                     return 0.5 * (1 + Engineering::erfVal(($value - $mean) / ($stdDev * sqrt(2))));
                 }
 
-                return (1 / (self::SQRT2PI * $stdDev)) * exp(0 - (pow($value - $mean, 2) / (2 * ($stdDev * $stdDev))));
+                return (1 / (self::SQRT2PI * $stdDev)) * exp(0 - (($value - $mean) ** 2 / (2 * ($stdDev * $stdDev))));
             }
         }
 
@@ -2695,7 +2694,6 @@ class Statistical
      * @category Statistical Functions
      *
      * @param mixed $args Data values
-     * @param float $entry Percentile value in the range 0..1, inclusive.
      *
      * @return float|string The result, or a string containing an error
      */
@@ -2841,13 +2839,13 @@ class Statistical
                     $summer = 0;
                     $floor = floor($value);
                     for ($i = 0; $i <= $floor; ++$i) {
-                        $summer += pow($mean, $i) / MathTrig::FACT($i);
+                        $summer += $mean ** $i / MathTrig::FACT($i);
                     }
 
                     return exp(0 - $mean) * $summer;
                 }
 
-                return (exp(0 - $mean) * pow($mean, $value)) / MathTrig::FACT($value);
+                return (exp(0 - $mean) * $mean ** $value) / MathTrig::FACT($value);
             }
         }
 
@@ -2865,7 +2863,6 @@ class Statistical
      * @category Statistical Functions
      *
      * @param mixed $args Data values
-     * @param int $entry Quartile value in the range 1..3, inclusive.
      *
      * @return float|string The result, or a string containing an error
      */
@@ -2979,7 +2976,7 @@ class Statistical
             } else {
                 // Is it a numeric value?
                 if ((is_numeric($arg)) && (!is_string($arg))) {
-                    $summer += pow((($arg - $mean) / $stdDev), 3);
+                    $summer += (($arg - $mean) / $stdDev) ** 3;
                     ++$count;
                 }
             }
@@ -3033,7 +3030,6 @@ class Statistical
      * @category Statistical Functions
      *
      * @param mixed $args Data values
-     * @param int $entry Position (ordered from the smallest) in the array or range of data to return
      *
      * @return float|string The result, or a string containing an error
      */
@@ -3126,9 +3122,9 @@ class Statistical
                 // Is it a numeric value?
                 if ((is_numeric($arg)) && (!is_string($arg))) {
                     if ($returnValue === null) {
-                        $returnValue = pow(($arg - $aMean), 2);
+                        $returnValue = ($arg - $aMean) ** 2;
                     } else {
-                        $returnValue += pow(($arg - $aMean), 2);
+                        $returnValue += ($arg - $aMean) ** 2;
                     }
                     ++$aCount;
                 }
@@ -3178,9 +3174,9 @@ class Statistical
                             $arg = 0;
                         }
                         if ($returnValue === null) {
-                            $returnValue = pow(($arg - $aMean), 2);
+                            $returnValue = ($arg - $aMean) ** 2;
                         } else {
-                            $returnValue += pow(($arg - $aMean), 2);
+                            $returnValue += ($arg - $aMean) ** 2;
                         }
                         ++$aCount;
                     }
@@ -3226,9 +3222,9 @@ class Statistical
                 // Is it a numeric value?
                 if ((is_numeric($arg)) && (!is_string($arg))) {
                     if ($returnValue === null) {
-                        $returnValue = pow(($arg - $aMean), 2);
+                        $returnValue = ($arg - $aMean) ** 2;
                     } else {
-                        $returnValue += pow(($arg - $aMean), 2);
+                        $returnValue += ($arg - $aMean) ** 2;
                     }
                     ++$aCount;
                 }
@@ -3277,9 +3273,9 @@ class Statistical
                             $arg = 0;
                         }
                         if ($returnValue === null) {
-                            $returnValue = pow(($arg - $aMean), 2);
+                            $returnValue = ($arg - $aMean) ** 2;
                         } else {
-                            $returnValue += pow(($arg - $aMean), 2);
+                            $returnValue += ($arg - $aMean) ** 2;
                         }
                         ++$aCount;
                     }
@@ -3491,7 +3487,6 @@ class Statistical
      * @category Statistical Functions
      *
      * @param mixed $args Data values
-     * @param float $discard Percentage to discard
      *
      * @return float|string
      */
@@ -3746,10 +3741,10 @@ class Statistical
             }
             if ((is_numeric($cumulative)) || (is_bool($cumulative))) {
                 if ($cumulative) {
-                    return 1 - exp(0 - pow($value / $beta, $alpha));
+                    return 1 - exp(0 - ($value / $beta) ** $alpha);
                 }
 
-                return ($alpha / pow($beta, $alpha)) * pow($value, $alpha - 1) * exp(0 - pow($value / $beta, $alpha));
+                return ($alpha / $beta ** $alpha) * $value ** ($alpha - 1) * exp(0 - ($value / $beta) ** $alpha);
             }
         }
 

src/PhpSpreadsheet/Calculation/TextData.php

@@ -167,7 +167,7 @@ class TextData
         if ($decimals > 0) {
             $mask .= '.' . str_repeat('0', $decimals);
         } else {
-            $round = pow(10, abs($decimals));
+            $round = 10 ** abs($decimals);
             if ($value < 0) {
                 $round = 0 - $round;
             }
@@ -623,7 +623,7 @@ class TextData
             $percentageAdjustment = strlen($value) - strlen($percentageString);
             if ($percentageAdjustment) {
                 $value = (float) $percentageString;
-                $value /= pow(10, $percentageAdjustment * 2);
+                $value /= 10 ** ($percentageAdjustment * 2);
             }
         }
 

src/PhpSpreadsheet/Calculation/Token/Stack.php

@@ -49,7 +49,7 @@ class Stack
         $storeKey = null,
         $onlyIf = null,
         $onlyIfNot = null
-    ) {
+    ): void {
         $stackItem = $this->getStackItem($type, $value, $reference, $storeKey, $onlyIf, $onlyIfNot);
 
         $this->stack[$this->count++] = $stackItem;
@@ -124,7 +124,7 @@ class Stack
     /**
      * Clear the stack.
      */
-    public function clear()
+    public function clear(): void
     {
         $this->stack = [];
         $this->count = 0;

src/PhpSpreadsheet/Cell/Cell.php

@@ -76,12 +76,12 @@ class Cell
         return $this;
     }
 
-    public function detach()
+    public function detach(): void
     {
         $this->parent = null;
     }
 
-    public function attach(Cells $parent)
+    public function attach(Cells $parent): void
     {
         $this->parent = $parent;
     }
@@ -91,7 +91,6 @@ class Cell
      *
      * @param mixed $pValue
      * @param string $pDataType
-     * @param Worksheet $pSheet
      */
     public function __construct($pValue, $pDataType, Worksheet $pSheet)
     {
@@ -386,7 +385,7 @@ class Cell
      *
      * @return Cell
      */
-    public function setDataValidation(DataValidation $pDataValidation = null)
+    public function setDataValidation(?DataValidation $pDataValidation = null)
     {
         if (!isset($this->parent)) {
             throw new Exception('Cannot set data validation for cell that is not bound to a worksheet');
@@ -444,7 +443,7 @@ class Cell
      *
      * @return Cell
      */
-    public function setHyperlink(Hyperlink $pHyperlink = null)
+    public function setHyperlink(?Hyperlink $pHyperlink = null)
     {
         if (!isset($this->parent)) {
             throw new Exception('Cannot set hyperlink for cell that is not bound to a worksheet');
@@ -532,8 +531,6 @@ class Cell
     /**
      * Re-bind parent.
      *
-     * @param Worksheet $parent
-     *
      * @return Cell
      */
     public function rebindParent(Worksheet $parent)
@@ -600,10 +597,8 @@ class Cell
 
     /**
      * Set value binder to use.
-     *
-     * @param IValueBinder $binder
      */
-    public static function setValueBinder(IValueBinder $binder)
+    public static function setValueBinder(IValueBinder $binder): void
     {
         self::$valueBinder = $binder;
     }

src/PhpSpreadsheet/Cell/Coordinate.php

@@ -503,7 +503,7 @@ abstract class Coordinate
      * @param int $currentRow
      * @param int $endRow
      */
-    private static function validateRange($cellBlock, $startColumnIndex, $endColumnIndex, $currentRow, $endRow)
+    private static function validateRange($cellBlock, $startColumnIndex, $endColumnIndex, $currentRow, $endRow): void
     {
         if ($startColumnIndex >= $endColumnIndex || $currentRow > $endRow) {
             throw new Exception('Invalid range: "' . $cellBlock . '"');

src/PhpSpreadsheet/Chart/Axis.php

@@ -178,7 +178,7 @@ class Axis extends Properties
      * @param string $major_unit
      * @param string $minor_unit
      */
-    public function setAxisOptionsProperties($axis_labels, $horizontal_crosses_value = null, $horizontal_crosses = null, $axis_orientation = null, $major_tmt = null, $minor_tmt = null, $minimum = null, $maximum = null, $major_unit = null, $minor_unit = null)
+    public function setAxisOptionsProperties($axis_labels, $horizontal_crosses_value = null, $horizontal_crosses = null, $axis_orientation = null, $major_tmt = null, $minor_tmt = null, $minimum = null, $maximum = null, $major_unit = null, $minor_unit = null): void
     {
         $this->axisOptions['axis_labels'] = (string) $axis_labels;
         ($horizontal_crosses_value !== null) ? $this->axisOptions['horizontal_crosses_value'] = (string) $horizontal_crosses_value : null;
@@ -210,7 +210,7 @@ class Axis extends Properties
      *
      * @param string $orientation
      */
-    public function setAxisOrientation($orientation)
+    public function setAxisOrientation($orientation): void
     {
         $this->axisOptions['orientation'] = (string) $orientation;
     }
@@ -222,7 +222,7 @@ class Axis extends Properties
      * @param int $alpha
      * @param string $type
      */
-    public function setFillParameters($color, $alpha = 0, $type = self::EXCEL_COLOR_TYPE_ARGB)
+    public function setFillParameters($color, $alpha = 0, $type = self::EXCEL_COLOR_TYPE_ARGB): void
     {
         $this->fillProperties = $this->setColorProperties($color, $alpha, $type);
     }
@@ -234,7 +234,7 @@ class Axis extends Properties
      * @param int $alpha
      * @param string $type
      */
-    public function setLineParameters($color, $alpha = 0, $type = self::EXCEL_COLOR_TYPE_ARGB)
+    public function setLineParameters($color, $alpha = 0, $type = self::EXCEL_COLOR_TYPE_ARGB): void
     {
         $this->lineProperties = $this->setColorProperties($color, $alpha, $type);
     }
@@ -276,7 +276,7 @@ class Axis extends Properties
      * @param string $end_arrow_type
      * @param string $end_arrow_size
      */
-    public function setLineStyleProperties($line_width = null, $compound_type = null, $dash_type = null, $cap_type = null, $join_type = null, $head_arrow_type = null, $head_arrow_size = null, $end_arrow_type = null, $end_arrow_size = null)
+    public function setLineStyleProperties($line_width = null, $compound_type = null, $dash_type = null, $cap_type = null, $join_type = null, $head_arrow_type = null, $head_arrow_size = null, $end_arrow_type = null, $end_arrow_size = null): void
     {
         ($line_width !== null) ? $this->lineStyleProperties['width'] = $this->getExcelPointsWidth((float) $line_width) : null;
         ($compound_type !== null) ? $this->lineStyleProperties['compound'] = (string) $compound_type : null;
@@ -336,7 +336,7 @@ class Axis extends Properties
      * @param int $sh_angle
      * @param float $sh_distance
      */
-    public function setShadowProperties($sh_presets, $sh_color_value = null, $sh_color_type = null, $sh_color_alpha = null, $sh_blur = null, $sh_angle = null, $sh_distance = null)
+    public function setShadowProperties($sh_presets, $sh_color_value = null, $sh_color_type = null, $sh_color_alpha = null, $sh_blur = null, $sh_angle = null, $sh_distance = null): void
     {
         $this->setShadowPresetsProperties((int) $sh_presets)
             ->setShadowColor(
@@ -367,7 +367,6 @@ class Axis extends Properties
     /**
      * Set Shadow Properties from Mapped Values.
      *
-     * @param array $properties_map
      * @param mixed &$reference
      *
      * @return $this
@@ -479,7 +478,7 @@ class Axis extends Properties
      * @param int $color_alpha
      * @param string $color_type
      */
-    public function setGlowProperties($size, $color_value = null, $color_alpha = null, $color_type = null)
+    public function setGlowProperties($size, $color_value = null, $color_alpha = null, $color_type = null): void
     {
         $this->setGlowSize($size)
             ->setGlowColor(
@@ -538,7 +537,7 @@ class Axis extends Properties
      *
      * @param float $size
      */
-    public function setSoftEdges($size)
+    public function setSoftEdges($size): void
     {
         if ($size !== null) {
             $softEdges['size'] = (string) $this->getExcelPointsWidth($size);

src/PhpSpreadsheet/Chart/Chart.php

@@ -144,19 +144,10 @@ class Chart
      * Create a new Chart.
      *
      * @param mixed $name
-     * @param null|Title $title
-     * @param null|Legend $legend
-     * @param null|PlotArea $plotArea
      * @param mixed $plotVisibleOnly
      * @param string $displayBlanksAs
-     * @param null|Title $xAxisLabel
-     * @param null|Title $yAxisLabel
-     * @param null|Axis $xAxis
-     * @param null|Axis $yAxis
-     * @param null|GridLines $majorGridlines
-     * @param null|GridLines $minorGridlines
      */
-    public function __construct($name, Title $title = null, Legend $legend = null, PlotArea $plotArea = null, $plotVisibleOnly = true, $displayBlanksAs = DataSeries::EMPTY_AS_GAP, Title $xAxisLabel = null, Title $yAxisLabel = null, Axis $xAxis = null, Axis $yAxis = null, GridLines $majorGridlines = null, GridLines $minorGridlines = null)
+    public function __construct($name, ?Title $title = null, ?Legend $legend = null, ?PlotArea $plotArea = null, $plotVisibleOnly = true, $displayBlanksAs = DataSeries::EMPTY_AS_GAP, ?Title $xAxisLabel = null, ?Title $yAxisLabel = null, ?Axis $xAxis = null, ?Axis $yAxis = null, ?GridLines $majorGridlines = null, ?GridLines $minorGridlines = null)
     {
         $this->name = $name;
         $this->title = $title;
@@ -199,7 +190,7 @@ class Chart
      *
      * @return $this
      */
-    public function setWorksheet(Worksheet $pValue = null)
+    public function setWorksheet(?Worksheet $pValue = null)
     {
         $this->worksheet = $pValue;
 
@@ -219,8 +210,6 @@ class Chart
     /**
      * Set Title.
      *
-     * @param Title $title
-     *
      * @return $this
      */
     public function setTitle(Title $title)
@@ -243,8 +232,6 @@ class Chart
     /**
      * Set Legend.
      *
-     * @param Legend $legend
-     *
      * @return $this
      */
     public function setLegend(Legend $legend)
@@ -267,8 +254,6 @@ class Chart
     /**
      * Set X-Axis Label.
      *
-     * @param Title $label
-     *
      * @return $this
      */
     public function setXAxisLabel(Title $label)
@@ -291,8 +276,6 @@ class Chart
     /**
      * Set Y-Axis Label.
      *
-     * @param Title $label
-     *
      * @return $this
      */
     public function setYAxisLabel(Title $label)
@@ -645,7 +628,7 @@ class Chart
         return $this->bottomRightYOffset;
     }
 
-    public function refresh()
+    public function refresh(): void
     {
         if ($this->worksheet !== null) {
             $this->plotArea->refresh($this->worksheet);

src/PhpSpreadsheet/Chart/DataSeries.php

@@ -373,7 +373,7 @@ class DataSeries
         return $this;
     }
 
-    public function refresh(Worksheet $worksheet)
+    public function refresh(Worksheet $worksheet): void
     {
         foreach ($this->plotValues as $plotValues) {
             if ($plotValues !== null) {

src/PhpSpreadsheet/Chart/DataSeriesValues.php

@@ -352,7 +352,7 @@ class DataSeriesValues
         return $this;
     }
 
-    public function refresh(Worksheet $worksheet, $flatten = true)
+    public function refresh(Worksheet $worksheet, $flatten = true): void
     {
         if ($this->dataSource !== null) {
             $calcEngine = Calculation::getInstance($worksheet->getParent());

src/PhpSpreadsheet/Chart/GridLines.php

@@ -107,7 +107,7 @@ class GridLines extends Properties
      * @param int $alpha
      * @param string $type
      */
-    public function setLineColorProperties($value, $alpha = 0, $type = self::EXCEL_COLOR_TYPE_STANDARD)
+    public function setLineColorProperties($value, $alpha = 0, $type = self::EXCEL_COLOR_TYPE_STANDARD): void
     {
         $this->activateObject()
             ->lineProperties['color'] = $this->setColorProperties(
@@ -130,7 +130,7 @@ class GridLines extends Properties
      * @param string $end_arrow_type
      * @param string $end_arrow_size
      */
-    public function setLineStyleProperties($line_width = null, $compound_type = null, $dash_type = null, $cap_type = null, $join_type = null, $head_arrow_type = null, $head_arrow_size = null, $end_arrow_type = null, $end_arrow_size = null)
+    public function setLineStyleProperties($line_width = null, $compound_type = null, $dash_type = null, $cap_type = null, $join_type = null, $head_arrow_type = null, $head_arrow_size = null, $end_arrow_type = null, $end_arrow_size = null): void
     {
         $this->activateObject();
         ($line_width !== null)
@@ -194,7 +194,7 @@ class GridLines extends Properties
      * @param int $color_alpha
      * @param string $color_type
      */
-    public function setGlowProperties($size, $color_value = null, $color_alpha = null, $color_type = null)
+    public function setGlowProperties($size, $color_value = null, $color_alpha = null, $color_type = null): void
     {
         $this
             ->activateObject()
@@ -286,7 +286,7 @@ class GridLines extends Properties
      * @param int $sh_angle
      * @param float $sh_distance
      */
-    public function setShadowProperties($sh_presets, $sh_color_value = null, $sh_color_type = null, $sh_color_alpha = null, $sh_blur = null, $sh_angle = null, $sh_distance = null)
+    public function setShadowProperties($sh_presets, $sh_color_value = null, $sh_color_type = null, $sh_color_alpha = null, $sh_blur = null, $sh_angle = null, $sh_distance = null): void
     {
         $this->activateObject()
             ->setShadowPresetsProperties((int) $sh_presets)
@@ -318,7 +318,6 @@ class GridLines extends Properties
     /**
      * Set Shadow Properties Values.
      *
-     * @param array $properties_map
      * @param mixed &$reference
      *
      * @return $this
@@ -435,7 +434,7 @@ class GridLines extends Properties
      *
      * @param float $size
      */
-    public function setSoftEdgesSize($size)
+    public function setSoftEdgesSize($size): void
     {
         if ($size !== null) {
             $this->activateObject();

src/PhpSpreadsheet/Chart/Layout.php

@@ -110,8 +110,6 @@ class Layout
 
     /**
      * Create a new Layout.
-     *
-     * @param array $layout
      */
     public function __construct(array $layout = [])
     {

src/PhpSpreadsheet/Chart/Legend.php

@@ -52,10 +52,9 @@ class Legend
      * Create a new Legend.
      *
      * @param string $position
-     * @param null|Layout $layout
      * @param bool $overlay
      */
-    public function __construct($position = self::POSITION_RIGHT, Layout $layout = null, $overlay = false)
+    public function __construct($position = self::POSITION_RIGHT, ?Layout $layout = null, $overlay = false)
     {
         $this->setPosition($position);
         $this->layout = $layout;

src/PhpSpreadsheet/Chart/PlotArea.php

@@ -23,10 +23,9 @@ class PlotArea
     /**
      * Create a new PlotArea.
      *
-     * @param null|Layout $layout
      * @param DataSeries[] $plotSeries
      */
-    public function __construct(Layout $layout = null, array $plotSeries = [])
+    public function __construct(?Layout $layout = null, array $plotSeries = [])
     {
         $this->layout = $layout;
         $this->plotSeries = $plotSeries;
@@ -103,7 +102,7 @@ class PlotArea
         return $this;
     }
 
-    public function refresh(Worksheet $worksheet)
+    public function refresh(Worksheet $worksheet): void
     {
         foreach ($this->plotSeries as $plotSeries) {
             $plotSeries->refresh($worksheet);

src/PhpSpreadsheet/Chart/Renderer/IRenderer.php

@@ -8,8 +8,6 @@ interface IRenderer
 {
     /**
      * IRenderer constructor.
-     *
-     * @param \PhpOffice\PhpSpreadsheet\Chart\Chart $chart
      */
     public function __construct(Chart $chart);
 

src/PhpSpreadsheet/Chart/Renderer/JpGraph.php

@@ -2,8 +2,24 @@
 
 namespace PhpOffice\PhpSpreadsheet\Chart\Renderer;
 
+use AccBarPlot;
+use AccLinePlot;
+use BarPlot;
+use ContourPlot;
+use Graph;
+use GroupBarPlot;
+use LinePlot;
 use PhpOffice\PhpSpreadsheet\Chart\Chart;
 use PhpOffice\PhpSpreadsheet\Style\NumberFormat;
+use PieGraph;
+use PiePlot;
+use PiePlot3D;
+use PiePlotC;
+use RadarGraph;
+use RadarPlot;
+use ScatterPlot;
+use Spline;
+use StockPlot;
 
 require_once __DIR__ . '/Polyfill.php';
 
@@ -33,8 +49,6 @@ class JpGraph implements IRenderer
 
     /**
      * Create a new jpgraph.
-     *
-     * @param Chart $chart
      */
     public function __construct(Chart $chart)
     {
@@ -43,7 +57,7 @@ class JpGraph implements IRenderer
         $this->chart = $chart;
     }
 
-    private static function init()
+    private static function init(): void
     {
         static $loaded = false;
         if ($loaded) {
@@ -179,7 +193,7 @@ class JpGraph implements IRenderer
         return $caption;
     }
 
-    private function renderTitle()
+    private function renderTitle(): void
     {
         $title = $this->getCaption($this->chart->getTitle());
         if ($title !== null) {
@@ -187,7 +201,7 @@ class JpGraph implements IRenderer
         }
     }
 
-    private function renderLegend()
+    private function renderLegend(): void
     {
         $legend = $this->chart->getLegend();
         if ($legend !== null) {
@@ -220,9 +234,9 @@ class JpGraph implements IRenderer
         }
     }
 
-    private function renderCartesianPlotArea($type = 'textlin')
+    private function renderCartesianPlotArea($type = 'textlin'): void
     {
-        $this->graph = new \Graph(self::$width, self::$height);
+        $this->graph = new Graph(self::$width, self::$height);
         $this->graph->SetScale($type);
 
         $this->renderTitle();
@@ -257,22 +271,22 @@ class JpGraph implements IRenderer
         }
     }
 
-    private function renderPiePlotArea()
+    private function renderPiePlotArea(): void
     {
-        $this->graph = new \PieGraph(self::$width, self::$height);
+        $this->graph = new PieGraph(self::$width, self::$height);
 
         $this->renderTitle();
     }
 
-    private function renderRadarPlotArea()
+    private function renderRadarPlotArea(): void
     {
-        $this->graph = new \RadarGraph(self::$width, self::$height);
+        $this->graph = new RadarGraph(self::$width, self::$height);
         $this->graph->SetScale('lin');
 
         $this->renderTitle();
     }
 
-    private function renderPlotLine($groupID, $filled = false, $combination = false, $dimensions = '2d')
+    private function renderPlotLine($groupID, $filled = false, $combination = false, $dimensions = '2d'): void
     {
         $grouping = $this->chart->getPlotArea()->getPlotGroupByIndex($groupID)->getPlotGrouping();
 
@@ -308,7 +322,7 @@ class JpGraph implements IRenderer
                 ++$testCurrentIndex;
             }
 
-            $seriesPlot = new \LinePlot($dataValues);
+            $seriesPlot = new LinePlot($dataValues);
             if ($combination) {
                 $seriesPlot->SetBarCenter();
             }
@@ -330,12 +344,12 @@ class JpGraph implements IRenderer
         if ($grouping == 'standard') {
             $groupPlot = $seriesPlots;
         } else {
-            $groupPlot = new \AccLinePlot($seriesPlots);
+            $groupPlot = new AccLinePlot($seriesPlots);
         }
         $this->graph->Add($groupPlot);
     }
 
-    private function renderPlotBar($groupID, $dimensions = '2d')
+    private function renderPlotBar($groupID, $dimensions = '2d'): void
     {
         $rotation = $this->chart->getPlotArea()->getPlotGroupByIndex($groupID)->getPlotDirection();
         //    Rotate for bar rather than column chart
@@ -385,7 +399,7 @@ class JpGraph implements IRenderer
             if ($rotation == 'bar') {
                 $dataValues = array_reverse($dataValues);
             }
-            $seriesPlot = new \BarPlot($dataValues);
+            $seriesPlot = new BarPlot($dataValues);
             $seriesPlot->SetColor('black');
             $seriesPlot->SetFillColor(self::$colourSet[self::$plotColour++]);
             if ($dimensions == '3d') {
@@ -406,11 +420,11 @@ class JpGraph implements IRenderer
         }
 
         if ($grouping == 'clustered') {
-            $groupPlot = new \GroupBarPlot($seriesPlots);
+            $groupPlot = new GroupBarPlot($seriesPlots);
         } elseif ($grouping == 'standard') {
-            $groupPlot = new \GroupBarPlot($seriesPlots);
+            $groupPlot = new GroupBarPlot($seriesPlots);
         } else {
-            $groupPlot = new \AccBarPlot($seriesPlots);
+            $groupPlot = new AccBarPlot($seriesPlots);
             if ($dimensions == '3d') {
                 $groupPlot->SetShadow();
             }
@@ -419,7 +433,7 @@ class JpGraph implements IRenderer
         $this->graph->Add($groupPlot);
     }
 
-    private function renderPlotScatter($groupID, $bubble)
+    private function renderPlotScatter($groupID, $bubble): void
     {
         $grouping = $this->chart->getPlotArea()->getPlotGroupByIndex($groupID)->getPlotGrouping();
         $scatterStyle = $bubbleSize = $this->chart->getPlotArea()->getPlotGroupByIndex($groupID)->getPlotStyle();
@@ -436,14 +450,14 @@ class JpGraph implements IRenderer
                 $dataValuesY[$k] = $k;
             }
 
-            $seriesPlot = new \ScatterPlot($dataValuesX, $dataValuesY);
+            $seriesPlot = new ScatterPlot($dataValuesX, $dataValuesY);
             if ($scatterStyle == 'lineMarker') {
                 $seriesPlot->SetLinkPoints();
                 $seriesPlot->link->SetColor(self::$colourSet[self::$plotColour]);
             } elseif ($scatterStyle == 'smoothMarker') {
-                $spline = new \Spline($dataValuesY, $dataValuesX);
+                $spline = new Spline($dataValuesY, $dataValuesX);
                 [$splineDataY, $splineDataX] = $spline->Get(count($dataValuesX) * self::$width / 20);
-                $lplot = new \LinePlot($splineDataX, $splineDataY);
+                $lplot = new LinePlot($splineDataX, $splineDataY);
                 $lplot->SetColor(self::$colourSet[self::$plotColour]);
 
                 $this->graph->Add($lplot);
@@ -464,7 +478,7 @@ class JpGraph implements IRenderer
         }
     }
 
-    private function renderPlotRadar($groupID)
+    private function renderPlotRadar($groupID): void
     {
         $radarStyle = $this->chart->getPlotArea()->getPlotGroupByIndex($groupID)->getPlotStyle();
 
@@ -488,7 +502,7 @@ class JpGraph implements IRenderer
 
             $this->graph->SetTitles(array_reverse($dataValues));
 
-            $seriesPlot = new \RadarPlot(array_reverse($dataValuesX));
+            $seriesPlot = new RadarPlot(array_reverse($dataValuesX));
 
             $dataLabel = $this->chart->getPlotArea()->getPlotGroupByIndex($groupID)->getPlotLabelByIndex($i)->getDataValue();
             $seriesPlot->SetColor(self::$colourSet[self::$plotColour++]);
@@ -502,7 +516,7 @@ class JpGraph implements IRenderer
         }
     }
 
-    private function renderPlotContour($groupID)
+    private function renderPlotContour($groupID): void
     {
         $contourStyle = $this->chart->getPlotArea()->getPlotGroupByIndex($groupID)->getPlotStyle();
 
@@ -517,12 +531,12 @@ class JpGraph implements IRenderer
 
             $dataValues[$i] = $dataValuesX;
         }
-        $seriesPlot = new \ContourPlot($dataValues);
+        $seriesPlot = new ContourPlot($dataValues);
 
         $this->graph->Add($seriesPlot);
     }
 
-    private function renderPlotStock($groupID)
+    private function renderPlotStock($groupID): void
     {
         $seriesCount = $this->chart->getPlotArea()->getPlotGroupByIndex($groupID)->getPlotSeriesCount();
         $plotOrder = $this->chart->getPlotArea()->getPlotGroupByIndex($groupID)->getPlotOrder();
@@ -556,13 +570,13 @@ class JpGraph implements IRenderer
             $this->graph->xaxis->SetTickLabels($datasetLabels);
         }
 
-        $seriesPlot = new \StockPlot($dataValuesPlot);
+        $seriesPlot = new StockPlot($dataValuesPlot);
         $seriesPlot->SetWidth(20);
 
         $this->graph->Add($seriesPlot);
     }
 
-    private function renderAreaChart($groupCount, $dimensions = '2d')
+    private function renderAreaChart($groupCount, $dimensions = '2d'): void
     {
         $this->renderCartesianPlotArea();
 
@@ -571,7 +585,7 @@ class JpGraph implements IRenderer
         }
     }
 
-    private function renderLineChart($groupCount, $dimensions = '2d')
+    private function renderLineChart($groupCount, $dimensions = '2d'): void
     {
         $this->renderCartesianPlotArea();
 
@@ -580,7 +594,7 @@ class JpGraph implements IRenderer
         }
     }
 
-    private function renderBarChart($groupCount, $dimensions = '2d')
+    private function renderBarChart($groupCount, $dimensions = '2d'): void
     {
         $this->renderCartesianPlotArea();
 
@@ -589,7 +603,7 @@ class JpGraph implements IRenderer
         }
     }
 
-    private function renderScatterChart($groupCount)
+    private function renderScatterChart($groupCount): void
     {
         $this->renderCartesianPlotArea('linlin');
 
@@ -598,7 +612,7 @@ class JpGraph implements IRenderer
         }
     }
 
-    private function renderBubbleChart($groupCount)
+    private function renderBubbleChart($groupCount): void
     {
         $this->renderCartesianPlotArea('linlin');
 
@@ -607,7 +621,7 @@ class JpGraph implements IRenderer
         }
     }
 
-    private function renderPieChart($groupCount, $dimensions = '2d', $doughnut = false, $multiplePlots = false)
+    private function renderPieChart($groupCount, $dimensions = '2d', $doughnut = false, $multiplePlots = false): void
     {
         $this->renderPiePlotArea();
 
@@ -643,12 +657,12 @@ class JpGraph implements IRenderer
                 }
 
                 if ($dimensions == '3d') {
-                    $seriesPlot = new \PiePlot3D($dataValues);
+                    $seriesPlot = new PiePlot3D($dataValues);
                 } else {
                     if ($doughnut) {
-                        $seriesPlot = new \PiePlotC($dataValues);
+                        $seriesPlot = new PiePlotC($dataValues);
                     } else {
-                        $seriesPlot = new \PiePlot($dataValues);
+                        $seriesPlot = new PiePlot($dataValues);
                     }
                 }
 
@@ -679,7 +693,7 @@ class JpGraph implements IRenderer
         }
     }
 
-    private function renderRadarChart($groupCount)
+    private function renderRadarChart($groupCount): void
     {
         $this->renderRadarPlotArea();
 
@@ -688,7 +702,7 @@ class JpGraph implements IRenderer
         }
     }
 
-    private function renderStockChart($groupCount)
+    private function renderStockChart($groupCount): void
     {
         $this->renderCartesianPlotArea('intint');
 
@@ -697,7 +711,7 @@ class JpGraph implements IRenderer
         }
     }
 
-    private function renderContourChart($groupCount, $dimensions)
+    private function renderContourChart($groupCount, $dimensions): void
     {
         $this->renderCartesianPlotArea('intint');
 

src/PhpSpreadsheet/Chart/Renderer/Polyfill.php

@@ -2,7 +2,7 @@
 
 // This is a dirty workaround to output JpGraph charts even when antialiasing is not available
 if (!function_exists('imageantialias')) {
-    function imageantialias(...$args)
+    function imageantialias(...$args): void
     {
         // Do nothing
     }

src/PhpSpreadsheet/Chart/Title.php

@@ -22,9 +22,8 @@ class Title
      * Create a new Title.
      *
      * @param null|mixed $caption
-     * @param null|Layout $layout
      */
-    public function __construct($caption = null, Layout $layout = null)
+    public function __construct($caption = null, ?Layout $layout = null)
     {
         $this->caption = $caption;
         $this->layout = $layout;

src/PhpSpreadsheet/Collection/Cells.php

@@ -2,6 +2,7 @@
 
 namespace PhpOffice\PhpSpreadsheet\Collection;
 
+use Generator;
 use PhpOffice\PhpSpreadsheet\Cell\Cell;
 use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
 use PhpOffice\PhpSpreadsheet\Exception as PhpSpreadsheetException;
@@ -61,7 +62,6 @@ class Cells
      * Initialise this new cell collection.
      *
      * @param Worksheet $parent The worksheet for this cell collection
-     * @param CacheInterface $cache
      */
     public function __construct(Worksheet $parent, CacheInterface $cache)
     {
@@ -117,7 +117,7 @@ class Cells
      *
      * @param string $pCoord Coordinate of the cell to delete
      */
-    public function delete($pCoord)
+    public function delete($pCoord): void
     {
         if ($pCoord === $this->currentCoordinate && $this->currentCell !== null) {
             $this->currentCell->detach();
@@ -346,7 +346,7 @@ class Cells
      *
      * @param string $row Row number to remove
      */
-    public function removeRow($row)
+    public function removeRow($row): void
     {
         foreach ($this->getCoordinates() as $coord) {
             $c = '';
@@ -364,7 +364,7 @@ class Cells
      *
      * @param string $column Column ID to remove
      */
-    public function removeColumn($column)
+    public function removeColumn($column): void
     {
         foreach ($this->getCoordinates() as $coord) {
             $c = '';
@@ -381,7 +381,7 @@ class Cells
      * Store cell data in cache for the current cell object if it's "dirty",
      * and the 'nullify' the current cell object.
      */
-    private function storeCurrentCell()
+    private function storeCurrentCell(): void
     {
         if ($this->currentCellIsDirty && !empty($this->currentCoordinate)) {
             $this->currentCell->detach();
@@ -459,7 +459,7 @@ class Cells
     /**
      * Clear the cell collection and disconnect from our parent.
      */
-    public function unsetWorksheetCells()
+    public function unsetWorksheetCells(): void
     {
         if ($this->currentCell !== null) {
             $this->currentCell->detach();
@@ -487,7 +487,7 @@ class Cells
     /**
      * Returns all known cache keys.
      *
-     * @return \Generator|string[]
+     * @return Generator|string[]
      */
     private function getAllCacheKeys()
     {

src/PhpSpreadsheet/Comment.php

@@ -118,8 +118,6 @@ class Comment implements IComparable
     /**
      * Set Rich text comment.
      *
-     * @param RichText $pValue
-     *
      * @return $this
      */
     public function setText(RichText $pValue)

src/PhpSpreadsheet/DocumentGenerator.php

@@ -11,8 +11,6 @@ class DocumentGenerator
 {
     /**
      * @param array[] $phpSpreadsheetFunctions
-     *
-     * @return string
      */
     public static function generateFunctionListByCategory(array $phpSpreadsheetFunctions): string
     {
@@ -40,7 +38,7 @@ class DocumentGenerator
         return (new ReflectionClass(Category::class))->getConstants();
     }
 
-    private static function tableRow(array $lengths, array $values = null): string
+    private static function tableRow(array $lengths, ?array $values = null): string
     {
         $result = '';
         foreach (array_map(null, $lengths, $values ?? []) as $i => [$length, $value]) {
@@ -73,8 +71,6 @@ class DocumentGenerator
 
     /**
      * @param array[] $phpSpreadsheetFunctions
-     *
-     * @return string
      */
     public static function generateFunctionListByName(array $phpSpreadsheetFunctions): string
     {

src/PhpSpreadsheet/HashTable.php

@@ -36,7 +36,7 @@ class HashTable
      *
      * @param IComparable[] $pSource Source array to create HashTable from
      */
-    public function addFromSource(array $pSource = null)
+    public function addFromSource(?array $pSource = null): void
     {
         // Check if an array was passed
         if ($pSource == null) {
@@ -53,7 +53,7 @@ class HashTable
      *
      * @param IComparable $pSource Item to add
      */
-    public function add(IComparable $pSource)
+    public function add(IComparable $pSource): void
     {
         $hash = $pSource->getHashCode();
         if (!isset($this->items[$hash])) {
@@ -67,7 +67,7 @@ class HashTable
      *
      * @param IComparable $pSource Item to remove
      */
-    public function remove(IComparable $pSource)
+    public function remove(IComparable $pSource): void
     {
         $hash = $pSource->getHashCode();
         if (isset($this->items[$hash])) {
@@ -90,7 +90,7 @@ class HashTable
     /**
      * Clear HashTable.
      */
-    public function clear()
+    public function clear(): void
     {
         $this->items = [];
         $this->keyMap = [];

src/PhpSpreadsheet/Helper/Html.php

@@ -593,7 +593,7 @@ class Html
      */
     protected $richTextObject;
 
-    protected function initialise()
+    protected function initialise(): void
     {
         $this->face = $this->size = $this->color = null;
         $this->bold = $this->italic = $this->underline = $this->superscript = $this->subscript = $this->strikethrough = false;
@@ -632,7 +632,7 @@ class Html
         return $this->richTextObject;
     }
 
-    protected function cleanWhitespace()
+    protected function cleanWhitespace(): void
     {
         foreach ($this->richTextObject->getRichTextElements() as $key => $element) {
             $text = $element->getText();
@@ -646,7 +646,7 @@ class Html
         }
     }
 
-    protected function buildTextRun()
+    protected function buildTextRun(): void
     {
         $text = $this->stringData;
         if (trim($text) === '') {
@@ -691,7 +691,7 @@ class Html
             $value = str_pad(dechex($value), 2, '0', STR_PAD_LEFT);
         }
 
-        return implode($values[0]);
+        return implode('', $values[0]);
     }
 
     protected function colourNameLookup($rgb)
@@ -699,7 +699,7 @@ class Html
         return self::$colourMap[$rgb];
     }
 
-    protected function startFontTag($tag)
+    protected function startFontTag($tag): void
     {
         foreach ($tag->attributes as $attribute) {
             $attributeName = strtolower($attribute->name);
@@ -719,77 +719,77 @@ class Html
         }
     }
 
-    protected function endFontTag()
+    protected function endFontTag(): void
     {
         $this->face = $this->size = $this->color = null;
     }
 
-    protected function startBoldTag()
+    protected function startBoldTag(): void
     {
         $this->bold = true;
     }
 
-    protected function endBoldTag()
+    protected function endBoldTag(): void
     {
         $this->bold = false;
     }
 
-    protected function startItalicTag()
+    protected function startItalicTag(): void
     {
         $this->italic = true;
     }
 
-    protected function endItalicTag()
+    protected function endItalicTag(): void
     {
         $this->italic = false;
     }
 
-    protected function startUnderlineTag()
+    protected function startUnderlineTag(): void
     {
         $this->underline = true;
     }
 
-    protected function endUnderlineTag()
+    protected function endUnderlineTag(): void
     {
         $this->underline = false;
     }
 
-    protected function startSubscriptTag()
+    protected function startSubscriptTag(): void
     {
         $this->subscript = true;
     }
 
-    protected function endSubscriptTag()
+    protected function endSubscriptTag(): void
     {
         $this->subscript = false;
     }
 
-    protected function startSuperscriptTag()
+    protected function startSuperscriptTag(): void
     {
         $this->superscript = true;
     }
 
-    protected function endSuperscriptTag()
+    protected function endSuperscriptTag(): void
     {
         $this->superscript = false;
     }
 
-    protected function startStrikethruTag()
+    protected function startStrikethruTag(): void
     {
         $this->strikethrough = true;
     }
 
-    protected function endStrikethruTag()
+    protected function endStrikethruTag(): void
     {
         $this->strikethrough = false;
     }
 
-    protected function breakTag()
+    protected function breakTag(): void
     {
         $this->stringData .= "\n";
     }
 
-    protected function parseTextNode(DOMText $textNode)
+    protected function parseTextNode(DOMText $textNode): void
     {
         $domText = preg_replace(
             '/\s+/u',
@@ -801,11 +801,9 @@ class Html
     }
 
     /**
-     * @param DOMElement $element
      * @param string $callbackTag
-     * @param array $callbacks
      */
-    protected function handleCallback(DOMElement $element, $callbackTag, array $callbacks)
+    protected function handleCallback(DOMElement $element, $callbackTag, array $callbacks): void
     {
         if (isset($callbacks[$callbackTag])) {
             $elementHandler = $callbacks[$callbackTag];
@@ -815,7 +813,7 @@ class Html
         }
     }
 
-    protected function parseElementNode(DOMElement $element)
+    protected function parseElementNode(DOMElement $element): void
     {
         $callbackTag = strtolower($element->nodeName);
         $this->stack[] = $callbackTag;
@@ -828,7 +826,7 @@ class Html
         $this->handleCallback($element, $callbackTag, $this->endTagCallbacks);
     }
 
-    protected function parseElements(DOMNode $element)
+    protected function parseElements(DOMNode $element): void
     {
         foreach ($element->childNodes as $child) {
             if ($child instanceof DOMText) {

src/PhpSpreadsheet/Helper/Sample.php

@@ -11,6 +11,7 @@ use RecursiveIteratorIterator;
 use RecursiveRegexIterator;
 use ReflectionClass;
 use RegexIterator;
+use RuntimeException;
 
 /**
  * Helper class to be used in sample code.
@@ -106,11 +107,10 @@ class Sample
     /**
      * Write documents.
      *
-     * @param Spreadsheet $spreadsheet
      * @param string $filename
      * @param string[] $writers
      */
-    public function write(Spreadsheet $spreadsheet, $filename, array $writers = ['Xlsx', 'Xls'])
+    public function write(Spreadsheet $spreadsheet, $filename, array $writers = ['Xlsx', 'Xls']): void
     {
         // Set active sheet index to the first sheet, so Excel opens this as the first sheet
         $spreadsheet->setActiveSheetIndex(0);
@@ -142,7 +142,7 @@ class Sample
         $tempFolder = sys_get_temp_dir() . '/phpspreadsheet';
         if (!is_dir($tempFolder)) {
             if (!mkdir($tempFolder) && !is_dir($tempFolder)) {
-                throw new \RuntimeException(sprintf('Directory "%s" was not created', $tempFolder));
+                throw new RuntimeException(sprintf('Directory "%s" was not created', $tempFolder));
             }
         }
 
@@ -179,7 +179,7 @@ class Sample
         return $temporaryFilename . '.' . $extension;
     }
 
-    public function log($message)
+    public function log($message): void
     {
         $eol = $this->isCli() ? PHP_EOL : '<br />';
         echo date('H:i:s ') . $message . $eol;
@@ -188,7 +188,7 @@ class Sample
     /**
      * Log ending notes.
      */
-    public function logEndingNotes()
+    public function logEndingNotes(): void
     {
         // Do not show execution time for index
         $this->log('Peak memory usage: ' . (memory_get_peak_usage(true) / 1024 / 1024) . 'MB');
@@ -197,11 +197,10 @@ class Sample
     /**
      * Log a line about the write operation.
      *
-     * @param IWriter $writer
      * @param string $path
      * @param float $callStartTime
      */
-    public function logWrite(IWriter $writer, $path, $callStartTime)
+    public function logWrite(IWriter $writer, $path, $callStartTime): void
     {
         $callEndTime = microtime(true);
         $callTime = $callEndTime - $callStartTime;
@@ -219,7 +218,7 @@ class Sample
      * @param string $path
      * @param float $callStartTime
      */
-    public function logRead($format, $path, $callStartTime)
+    public function logRead($format, $path, $callStartTime): void
     {
         $callEndTime = microtime(true);
         $callTime = $callEndTime - $callStartTime;

src/PhpSpreadsheet/IOFactory.php

@@ -37,7 +37,6 @@ abstract class IOFactory
     /**
      * Create Writer\IWriter.
      *
-     * @param Spreadsheet $spreadsheet
      * @param string $writerType Example: Xlsx
      *
      * @return Writer\IWriter
@@ -192,7 +191,7 @@ abstract class IOFactory
      * @param string $writerType
      * @param string $writerClass
      */
-    public static function registerWriter($writerType, $writerClass)
+    public static function registerWriter($writerType, $writerClass): void
     {
         if (!is_a($writerClass, Writer\IWriter::class, true)) {
             throw new Writer\Exception('Registered writers must implement ' . Writer\IWriter::class);
@@ -207,7 +206,7 @@ abstract class IOFactory
      * @param string $readerType
      * @param string $readerClass
      */
-    public static function registerReader($readerType, $readerClass)
+    public static function registerReader($readerType, $readerClass): void
     {
         if (!is_a($readerClass, Reader\IReader::class, true)) {
             throw new Reader\Exception('Registered readers must implement ' . Reader\IReader::class);

src/PhpSpreadsheet/NamedRange.php

@@ -45,7 +45,6 @@ class NamedRange
      * Create a new NamedRange.
      *
      * @param string $pName
-     * @param Worksheet $pWorksheet
      * @param string $pRange
      * @param bool $pLocalOnly
      * @param null|Worksheet $pScope Scope. Only applies when $pLocalOnly = true. Null for global scope.
@@ -123,7 +122,7 @@ class NamedRange
      *
      * @return $this
      */
-    public function setWorksheet(Worksheet $value = null)
+    public function setWorksheet(?Worksheet $value = null)
     {
         if ($value !== null) {
             $this->worksheet = $value;
@@ -196,11 +195,9 @@ class NamedRange
     /**
      * Set scope.
      *
-     * @param null|Worksheet $value
-     *
      * @return $this
      */
-    public function setScope(Worksheet $value = null)
+    public function setScope(?Worksheet $value = null)
     {
         $this->scope = $value;
         $this->localOnly = $value != null;

src/PhpSpreadsheet/Reader/BaseReader.php

@@ -145,12 +145,12 @@ abstract class BaseReader implements IReader
      *
      * @param string $pFilename
      */
-    protected function openFile($pFilename)
+    protected function openFile($pFilename): void
     {
         File::assertFile($pFilename);
 
         // Open file
-        $this->fileHandle = fopen($pFilename, 'r');
+        $this->fileHandle = fopen($pFilename, 'rb');
         if ($this->fileHandle === false) {
             throw new Exception('Could not open file ' . $pFilename . ' for reading.');
         }

src/PhpSpreadsheet/Reader/Csv.php

@@ -2,6 +2,7 @@
 
 namespace PhpOffice\PhpSpreadsheet\Reader;
 
+use InvalidArgumentException;
 use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
 use PhpOffice\PhpSpreadsheet\Shared\StringHelper;
 use PhpOffice\PhpSpreadsheet\Spreadsheet;
@@ -85,7 +86,7 @@ class Csv extends BaseReader
     /**
      * Move filepointer past any BOM marker.
      */
-    protected function skipBOM()
+    protected function skipBOM(): void
     {
         rewind($this->fileHandle);
 
@@ -101,7 +102,7 @@ class Csv extends BaseReader
     /**
      * Identify any separator that is explicitly set in the file.
      */
-    protected function checkSeparator()
+    protected function checkSeparator(): void
     {
         $line = fgets($this->fileHandle);
         if ($line === false) {
@@ -120,7 +121,7 @@ class Csv extends BaseReader
     /**
      * Infer the separator if it isn't explicitly set in the file or specified by the user.
      */
-    protected function inferSeparator()
+    protected function inferSeparator(): void
     {
         if ($this->delimiter !== null) {
             return;
@@ -178,7 +179,7 @@ class Csv extends BaseReader
             $meanSquareDeviations[$delimiter] = array_reduce(
                 $series,
                 function ($sum, $value) use ($median) {
-                    return $sum + pow($value - $median, 2);
+                    return $sum + ($value - $median) ** 2;
                 }
             ) / count($series);
         }
@@ -292,7 +293,7 @@ class Csv extends BaseReader
         return $this->loadIntoExisting($pFilename, $spreadsheet);
     }
 
-    private function openFileOrMemory($pFilename)
+    private function openFileOrMemory($pFilename): void
     {
         // Open file
         $fhandle = $this->canRead($pFilename);
@@ -303,7 +304,7 @@ class Csv extends BaseReader
         if ($this->inputEncoding !== 'UTF-8') {
             fclose($this->fileHandle);
             $entireFile = file_get_contents($pFilename);
-            $this->fileHandle = fopen('php://memory', 'r+');
+            $this->fileHandle = fopen('php://memory', 'r+b');
             $data = StringHelper::convertEncoding($entireFile, 'UTF-8', $this->inputEncoding);
             fwrite($this->fileHandle, $data);
             rewind($this->fileHandle);
@@ -314,7 +315,6 @@ class Csv extends BaseReader
      * Loads PhpSpreadsheet from file into PhpSpreadsheet instance.
      *
      * @param string $pFilename
-     * @param Spreadsheet $spreadsheet
      *
      * @return Spreadsheet
      */
@@ -508,7 +508,7 @@ class Csv extends BaseReader
         // Check if file exists
         try {
             $this->openFile($pFilename);
-        } catch (\InvalidArgumentException $e) {
+        } catch (InvalidArgumentException $e) {
             return false;
         }
 

src/PhpSpreadsheet/Reader/Gnumeric.php

@@ -58,7 +58,7 @@ class Gnumeric extends BaseReader
         }
 
         // Read signature data (first 3 bytes)
-        $fh = fopen($pFilename, 'r');
+        $fh = fopen($pFilename, 'rb');
         $data = fread($fh, 2);
         fclose($fh);
 
@@ -182,7 +182,6 @@ class Gnumeric extends BaseReader
      * Loads from file into Spreadsheet instance.
      *
      * @param string $pFilename
-     * @param Spreadsheet $spreadsheet
      *
      * @return Spreadsheet
      */
@@ -473,7 +472,7 @@ class Gnumeric extends BaseReader
                     $endColumn = ($styleAttributes['endCol'] > $maxCol) ? $maxCol : (int) $styleAttributes['endCol'];
                     $endColumn = Coordinate::stringFromColumnIndex($endColumn + 1);
                     $endRow = ($styleAttributes['endRow'] > $maxRow) ? $maxRow : $styleAttributes['endRow'];
-                    $endRow += 1;
+                    ++$endRow;
                     $cellRange = $startColumn . $startRow . ':' . $endColumn . $endRow;
 
                     $styleAttributes = $styleRegion->Style->attributes();

src/PhpSpreadsheet/Reader/Html.php

@@ -270,7 +270,7 @@ class Html extends BaseReader
         return array_pop($this->nestedColumn);
     }
 
-    protected function flushCell(Worksheet $sheet, $column, $row, &$cellContent)
+    protected function flushCell(Worksheet $sheet, $column, $row, &$cellContent): void
     {
         if (is_string($cellContent)) {
             //    Simple String content
@@ -290,13 +290,11 @@ class Html extends BaseReader
     }
 
     /**
-     * @param DOMNode $element
-     * @param Worksheet $sheet
      * @param int $row
      * @param string $column
      * @param string $cellContent
      */
-    protected function processDomElement(DOMNode $element, Worksheet $sheet, &$row, &$column, &$cellContent)
+    protected function processDomElement(DOMNode $element, Worksheet $sheet, &$row, &$column, &$cellContent): void
     {
         foreach ($element->childNodes as $child) {
             if ($child instanceof DOMText) {
@@ -577,7 +575,6 @@ class Html extends BaseReader
      * Loads PhpSpreadsheet from file into PhpSpreadsheet instance.
      *
      * @param string $pFilename
-     * @param Spreadsheet $spreadsheet
      *
      * @return Spreadsheet
      */
@@ -603,9 +600,6 @@ class Html extends BaseReader
      * Spreadsheet from content.
      *
      * @param string $content
-     * @param null|Spreadsheet $spreadsheet
-     *
-     * @return Spreadsheet
      */
     public function loadFromString($content, ?Spreadsheet $spreadsheet = null): Spreadsheet
     {
@@ -622,11 +616,6 @@ class Html extends BaseReader
 
     /**
      * Loads PhpSpreadsheet from DOMDocument into PhpSpreadsheet instance.
-     *
-     * @param DOMDocument $document
-     * @param Spreadsheet $spreadsheet
-     *
-     * @return Spreadsheet
      */
     private function loadDocument(DOMDocument $document, Spreadsheet $spreadsheet): Spreadsheet
     {
@@ -687,7 +676,7 @@ class Html extends BaseReader
      * @param string $column
      * @param array $attributeArray
      */
-    private function applyInlineStyle(&$sheet, $row, $column, $attributeArray)
+    private function applyInlineStyle(&$sheet, $row, $column, $attributeArray): void
     {
         if (!isset($attributeArray['style'])) {
             return;
@@ -852,12 +841,10 @@ class Html extends BaseReader
     }
 
     /**
-     * @param Worksheet $sheet
      * @param string    $column
      * @param int       $row
-     * @param array     $attributes
      */
-    private function insertImage(Worksheet $sheet, $column, $row, array $attributes)
+    private function insertImage(Worksheet $sheet, $column, $row, array $attributes): void
     {
         if (!isset($attributes['src'])) {
             return;
@@ -941,11 +928,10 @@ class Html extends BaseReader
     }
 
     /**
-     * @param Style  $cellStyle
      * @param string $styleValue
      * @param string $type
      */
-    private function setBorderStyle(Style $cellStyle, $styleValue, $type)
+    private function setBorderStyle(Style $cellStyle, $styleValue, $type): void
     {
         [, $borderStyle, $color] = explode(' ', $styleValue);
 

src/PhpSpreadsheet/Reader/IReader.php

@@ -118,8 +118,6 @@ interface IReader
     /**
      * Set read filter.
      *
-     * @param IReadFilter $pValue
-     *
      * @return IReader
      */
     public function setReadFilter(IReadFilter $pValue);

src/PhpSpreadsheet/Reader/Ods.php

@@ -4,6 +4,10 @@ namespace PhpOffice\PhpSpreadsheet\Reader;
 
 use DateTime;
 use DateTimeZone;
+use DOMAttr;
+use DOMDocument;
+use DOMElement;
+use DOMNode;
 use PhpOffice\PhpSpreadsheet\Calculation\Calculation;
 use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
 use PhpOffice\PhpSpreadsheet\Cell\DataType;
@@ -242,7 +246,6 @@ class Ods extends BaseReader
      * Loads PhpSpreadsheet from file into PhpSpreadsheet instance.
      *
      * @param string $pFilename
-     * @param Spreadsheet $spreadsheet
      *
      * @return Spreadsheet
      */
@@ -251,7 +254,7 @@ class Ods extends BaseReader
         File::assertFile($pFilename);
 
         $timezoneObj = new DateTimeZone('Europe/London');
-        $GMT = new \DateTimeZone('UTC');
+        $GMT = new DateTimeZone('UTC');
 
         $zip = new ZipArchive();
         if (!$zip->open($pFilename)) {
@@ -275,7 +278,7 @@ class Ods extends BaseReader
 
         // Content
 
-        $dom = new \DOMDocument('1.01', 'UTF-8');
+        $dom = new DOMDocument('1.01', 'UTF-8');
         $dom->loadXML(
             $this->securityScanner->scan($zip->getFromName('content.xml')),
             Settings::getLibXmlLoaderOptions()
@@ -291,12 +294,12 @@ class Ods extends BaseReader
             ->getElementsByTagNameNS($officeNs, 'spreadsheet');
 
         foreach ($spreadsheets as $workbookData) {
-            /** @var \DOMElement $workbookData */
+            /** @var DOMElement $workbookData */
             $tables = $workbookData->getElementsByTagNameNS($tableNs, 'table');
 
             $worksheetID = 0;
             foreach ($tables as $worksheetDataSet) {
-                /** @var \DOMElement $worksheetDataSet */
+                /** @var DOMElement $worksheetDataSet */
                 $worksheetName = $worksheetDataSet->getAttributeNS($tableNs, 'name');
 
                 // Check loadSheetsOnly
@@ -322,7 +325,7 @@ class Ods extends BaseReader
                 // Go through every child of table element
                 $rowID = 1;
                 foreach ($worksheetDataSet->childNodes as $childNode) {
-                    /** @var \DOMElement $childNode */
+                    /** @var DOMElement $childNode */
 
                     // Filter elements which are not under the "table" ns
                     if ($childNode->namespaceURI != $tableNs) {
@@ -395,11 +398,11 @@ class Ods extends BaseReader
 
                                 // Content
 
-                                /** @var \DOMElement[] $paragraphs */
+                                /** @var DOMElement[] $paragraphs */
                                 $paragraphs = [];
 
                                 foreach ($cellData->childNodes as $item) {
-                                    /** @var \DOMElement $item */
+                                    /** @var DOMElement $item */
 
                                     // Filter text:p elements
                                     if ($item->nodeName == 'text:p') {
@@ -649,22 +652,20 @@ class Ods extends BaseReader
     /**
      * Recursively scan element.
      *
-     * @param \DOMNode $element
-     *
      * @return string
      */
-    protected function scanElementForText(\DOMNode $element)
+    protected function scanElementForText(DOMNode $element)
     {
         $str = '';
         foreach ($element->childNodes as $child) {
-            /** @var \DOMNode $child */
+            /** @var DOMNode $child */
             if ($child->nodeType == XML_TEXT_NODE) {
                 $str .= $child->nodeValue;
             } elseif ($child->nodeType == XML_ELEMENT_NODE && $child->nodeName == 'text:s') {
                 // It's a space
 
                 // Multiple spaces?
-                /** @var \DOMAttr $cAttr */
+                /** @var DOMAttr $cAttr */
                 $cAttr = $child->attributes->getNamedItem('c');
                 if ($cAttr) {
                     $multiplier = (int) $cAttr->nodeValue;

src/PhpSpreadsheet/Reader/Ods/Properties.php

@@ -4,6 +4,7 @@ namespace PhpOffice\PhpSpreadsheet\Reader\Ods;
 
 use PhpOffice\PhpSpreadsheet\Document\Properties as DocumentProperties;
 use PhpOffice\PhpSpreadsheet\Spreadsheet;
+use SimpleXMLElement;
 
 class Properties
 {
@@ -14,7 +15,7 @@ class Properties
         $this->spreadsheet = $spreadsheet;
     }
 
-    public function load(\SimpleXMLElement $xml, $namespacesMeta)
+    public function load(SimpleXMLElement $xml, $namespacesMeta): void
     {
         $docProps = $this->spreadsheet->getProperties();
         $officeProperty = $xml->children($namespacesMeta['office']);
@@ -35,7 +36,7 @@ class Properties
         }
     }
 
-    private function setCoreProperties(DocumentProperties $docProps, \SimpleXMLElement $officePropertyDC)
+    private function setCoreProperties(DocumentProperties $docProps, SimpleXMLElement $officePropertyDC): void
     {
         foreach ($officePropertyDC as $propertyName => $propertyValue) {
             $propertyValue = (string) $propertyValue;
@@ -73,10 +74,10 @@ class Properties
 
     private function setMetaProperties(
         $namespacesMeta,
-        \SimpleXMLElement $propertyValue,
+        SimpleXMLElement $propertyValue,
         $propertyName,
         DocumentProperties $docProps
-    ) {
+    ): void {
         $propertyValueAttributes = $propertyValue->attributes($namespacesMeta['meta']);
         $propertyValue = (string) $propertyValue;
         switch ($propertyName) {
@@ -100,7 +101,7 @@ class Properties
         }
     }
 
-    private function setUserDefinedProperty($propertyValueAttributes, $propertyValue, DocumentProperties $docProps)
+    private function setUserDefinedProperty($propertyValueAttributes, $propertyValue, DocumentProperties $docProps): void
     {
         $propertyValueName = '';
         $propertyValueType = DocumentProperties::PROPERTY_TYPE_STRING;

src/PhpSpreadsheet/Reader/Security/XmlScanner.php

@@ -61,7 +61,7 @@ class XmlScanner
         return false;
     }
 
-    private function disableEntityLoaderCheck()
+    private function disableEntityLoaderCheck(): void
     {
         if (Settings::getLibXmlDisableEntityLoader()) {
             $libxmlDisableEntityLoaderValue = libxml_disable_entity_loader(true);
@@ -72,7 +72,7 @@ class XmlScanner
         }
     }
 
-    public static function shutdown()
+    public static function shutdown(): void
     {
         if (self::$libxmlDisableEntityLoaderValue !== null) {
             libxml_disable_entity_loader(self::$libxmlDisableEntityLoaderValue);
@@ -85,7 +85,7 @@ class XmlScanner
         self::shutdown();
     }
 
-    public function setAdditionalCallback(callable $callback)
+    public function setAdditionalCallback(callable $callback): void
     {
         $this->callback = $callback;
     }

src/PhpSpreadsheet/Reader/Slk.php

@@ -190,7 +190,6 @@ class Slk extends BaseReader
      * Loads PhpSpreadsheet from file into PhpSpreadsheet instance.
      *
      * @param string $pFilename
-     * @param Spreadsheet $spreadsheet
      *
      * @return Spreadsheet
      */

src/PhpSpreadsheet/Reader/Xls.php

@@ -1248,10 +1248,10 @@ class Xls extends BaseReader
                                         [$firstColumn, $firstRow] = Coordinate::coordinateFromString($coordinateStrings[0]);
                                         [$lastColumn, $lastRow] = Coordinate::coordinateFromString($coordinateStrings[1]);
 
-                                        if ($firstColumn == 'A' and $lastColumn == 'IV') {
+                                        if ($firstColumn == 'A' && $lastColumn == 'IV') {
                                             // then we have repeating rows
                                             $docSheet->getPageSetup()->setRowsToRepeatAtTop([$firstRow, $lastRow]);
-                                        } elseif ($firstRow == 1 and $lastRow == 65536) {
+                                        } elseif ($firstRow == 1 && $lastRow == 65536) {
                                             // then we have repeating columns
                                             $docSheet->getPageSetup()->setColumnsToRepeatAtLeft([$firstColumn, $lastColumn]);
                                         }
@@ -1348,7 +1348,7 @@ class Xls extends BaseReader
      *
      * @param string $pFilename
      */
-    private function loadOLE($pFilename)
+    private function loadOLE($pFilename): void
     {
         // OLE reader
         $ole = new OLERead();
@@ -1365,7 +1365,7 @@ class Xls extends BaseReader
     /**
      * Read summary information.
      */
-    private function readSummaryInformation()
+    private function readSummaryInformation(): void
     {
         if (!isset($this->summaryInformation)) {
             return;
@@ -1512,7 +1512,7 @@ class Xls extends BaseReader
     /**
      * Read additional document summary information.
      */
-    private function readDocumentSummaryInformation()
+    private function readDocumentSummaryInformation(): void
     {
         if (!isset($this->documentSummaryInformation)) {
             return;
@@ -1650,7 +1650,7 @@ class Xls extends BaseReader
     /**
      * Reads a general type of BIFF record. Does nothing except for moving stream pointer forward to next record.
      */
-    private function readDefault()
+    private function readDefault(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
 
@@ -1662,7 +1662,7 @@ class Xls extends BaseReader
      *    The NOTE record specifies a comment associated with a particular cell. In Excel 95 (BIFF7) and earlier versions,
      *        this record stores a note (cell note). This feature was significantly enhanced in Excel 97.
      */
-    private function readNote()
+    private function readNote(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -1715,7 +1715,7 @@ class Xls extends BaseReader
     /**
      * The TEXT Object record contains the text associated with a cell annotation.
      */
-    private function readTextObject()
+    private function readTextObject(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -1762,7 +1762,7 @@ class Xls extends BaseReader
     /**
      * Read BOF.
      */
-    private function readBof()
+    private function readBof(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = substr($this->data, $this->pos + 4, $length);
@@ -1813,7 +1813,7 @@ class Xls extends BaseReader
      * are based on the source of Spreadsheet-ParseExcel:
      * https://metacpan.org/release/Spreadsheet-ParseExcel
      */
-    private function readFilepass()
+    private function readFilepass(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
 
@@ -1963,7 +1963,7 @@ class Xls extends BaseReader
      * --    "OpenOffice.org's Documentation of the Microsoft
      *         Excel File Format"
      */
-    private function readCodepage()
+    private function readCodepage(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -1989,7 +1989,7 @@ class Xls extends BaseReader
      * --    "OpenOffice.org's Documentation of the Microsoft
      *         Excel File Format"
      */
-    private function readDateMode()
+    private function readDateMode(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -2007,7 +2007,7 @@ class Xls extends BaseReader
     /**
      * Read a FONT record.
      */
-    private function readFont()
+    private function readFont(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -2115,7 +2115,7 @@ class Xls extends BaseReader
      * --    "OpenOffice.org's Documentation of the Microsoft
      *         Excel File Format"
      */
-    private function readFormat()
+    private function readFormat(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -2152,7 +2152,7 @@ class Xls extends BaseReader
      * --    "OpenOffice.org's Documentation of the Microsoft
      *         Excel File Format"
      */
-    private function readXf()
+    private function readXf(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -2449,7 +2449,7 @@ class Xls extends BaseReader
         }
     }
 
-    private function readXfExt()
+    private function readXfExt(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -2498,7 +2498,7 @@ class Xls extends BaseReader
                             if (isset($this->mapCellXfIndex[$ixfe])) {
                                 $fill = $this->spreadsheet->getCellXfByIndex($this->mapCellXfIndex[$ixfe])->getFill();
                                 $fill->getStartColor()->setRGB($rgb);
-                                unset($fill->startcolorIndex); // normal color index does not apply, discard
+                                $fill->startcolorIndex = null; // normal color index does not apply, discard
                             }
                         }
 
@@ -2514,7 +2514,7 @@ class Xls extends BaseReader
                             if (isset($this->mapCellXfIndex[$ixfe])) {
                                 $fill = $this->spreadsheet->getCellXfByIndex($this->mapCellXfIndex[$ixfe])->getFill();
                                 $fill->getEndColor()->setRGB($rgb);
-                                unset($fill->endcolorIndex); // normal color index does not apply, discard
+                                $fill->endcolorIndex = null; // normal color index does not apply, discard
                             }
                         }
 
@@ -2530,7 +2530,7 @@ class Xls extends BaseReader
                             if (isset($this->mapCellXfIndex[$ixfe])) {
                                 $top = $this->spreadsheet->getCellXfByIndex($this->mapCellXfIndex[$ixfe])->getBorders()->getTop();
                                 $top->getColor()->setRGB($rgb);
-                                unset($top->colorIndex); // normal color index does not apply, discard
+                                $top->colorIndex = null; // normal color index does not apply, discard
                             }
                         }
 
@@ -2546,7 +2546,7 @@ class Xls extends BaseReader
                             if (isset($this->mapCellXfIndex[$ixfe])) {
                                 $bottom = $this->spreadsheet->getCellXfByIndex($this->mapCellXfIndex[$ixfe])->getBorders()->getBottom();
                                 $bottom->getColor()->setRGB($rgb);
-                                unset($bottom->colorIndex); // normal color index does not apply, discard
+                                $bottom->colorIndex = null; // normal color index does not apply, discard
                             }
                         }
 
@@ -2562,7 +2562,7 @@ class Xls extends BaseReader
                             if (isset($this->mapCellXfIndex[$ixfe])) {
                                 $left = $this->spreadsheet->getCellXfByIndex($this->mapCellXfIndex[$ixfe])->getBorders()->getLeft();
                                 $left->getColor()->setRGB($rgb);
-                                unset($left->colorIndex); // normal color index does not apply, discard
+                                $left->colorIndex = null; // normal color index does not apply, discard
                             }
                         }
 
@@ -2578,7 +2578,7 @@ class Xls extends BaseReader
                             if (isset($this->mapCellXfIndex[$ixfe])) {
                                 $right = $this->spreadsheet->getCellXfByIndex($this->mapCellXfIndex[$ixfe])->getBorders()->getRight();
                                 $right->getColor()->setRGB($rgb);
-                                unset($right->colorIndex); // normal color index does not apply, discard
+                                $right->colorIndex = null; // normal color index does not apply, discard
                             }
                         }
 
@@ -2594,7 +2594,7 @@ class Xls extends BaseReader
                             if (isset($this->mapCellXfIndex[$ixfe])) {
                                 $diagonal = $this->spreadsheet->getCellXfByIndex($this->mapCellXfIndex[$ixfe])->getBorders()->getDiagonal();
                                 $diagonal->getColor()->setRGB($rgb);
-                                unset($diagonal->colorIndex); // normal color index does not apply, discard
+                                $diagonal->colorIndex = null; // normal color index does not apply, discard
                             }
                         }
 
@@ -2610,7 +2610,7 @@ class Xls extends BaseReader
                             if (isset($this->mapCellXfIndex[$ixfe])) {
                                 $font = $this->spreadsheet->getCellXfByIndex($this->mapCellXfIndex[$ixfe])->getFont();
                                 $font->getColor()->setRGB($rgb);
-                                unset($font->colorIndex); // normal color index does not apply, discard
+                                $font->colorIndex = null; // normal color index does not apply, discard
                             }
                         }
 
@@ -2625,7 +2625,7 @@ class Xls extends BaseReader
     /**
      * Read STYLE record.
      */
-    private function readStyle()
+    private function readStyle(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -2662,7 +2662,7 @@ class Xls extends BaseReader
     /**
      * Read PALETTE record.
      */
-    private function readPalette()
+    private function readPalette(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -2694,7 +2694,7 @@ class Xls extends BaseReader
      * --    "OpenOffice.org's Documentation of the Microsoft
      *         Excel File Format"
      */
-    private function readSheet()
+    private function readSheet(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -2749,7 +2749,7 @@ class Xls extends BaseReader
     /**
      * Read EXTERNALBOOK record.
      */
-    private function readExternalBook()
+    private function readExternalBook(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -2811,7 +2811,7 @@ class Xls extends BaseReader
     /**
      * Read EXTERNNAME record.
      */
-    private function readExternName()
+    private function readExternName(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -2845,7 +2845,7 @@ class Xls extends BaseReader
     /**
      * Read EXTERNSHEET record.
      */
-    private function readExternSheet()
+    private function readExternSheet(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -2881,7 +2881,7 @@ class Xls extends BaseReader
      * --    "OpenOffice.org's Documentation of the Microsoft
      *         Excel File Format"
      */
-    private function readDefinedName()
+    private function readDefinedName(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -2935,7 +2935,7 @@ class Xls extends BaseReader
     /**
      * Read MSODRAWINGGROUP record.
      */
-    private function readMsoDrawingGroup()
+    private function readMsoDrawingGroup(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
 
@@ -2957,7 +2957,7 @@ class Xls extends BaseReader
      * --    "OpenOffice.org's Documentation of the Microsoft
      *         Excel File Format"
      */
-    private function readSst()
+    private function readSst(): void
     {
         // offset within (spliced) record data
         $pos = 0;
@@ -3138,7 +3138,7 @@ class Xls extends BaseReader
     /**
      * Read PRINTGRIDLINES record.
      */
-    private function readPrintGridlines()
+    private function readPrintGridlines(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3156,7 +3156,7 @@ class Xls extends BaseReader
     /**
      * Read DEFAULTROWHEIGHT record.
      */
-    private function readDefaultRowHeight()
+    private function readDefaultRowHeight(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3173,7 +3173,7 @@ class Xls extends BaseReader
     /**
      * Read SHEETPR record.
      */
-    private function readSheetPr()
+    private function readSheetPr(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3199,7 +3199,7 @@ class Xls extends BaseReader
     /**
      * Read HORIZONTALPAGEBREAKS record.
      */
-    private function readHorizontalPageBreaks()
+    private function readHorizontalPageBreaks(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3226,7 +3226,7 @@ class Xls extends BaseReader
     /**
      * Read VERTICALPAGEBREAKS record.
      */
-    private function readVerticalPageBreaks()
+    private function readVerticalPageBreaks(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3253,7 +3253,7 @@ class Xls extends BaseReader
     /**
      * Read HEADER record.
      */
-    private function readHeader()
+    private function readHeader(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3280,7 +3280,7 @@ class Xls extends BaseReader
     /**
      * Read FOOTER record.
      */
-    private function readFooter()
+    private function readFooter(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3306,7 +3306,7 @@ class Xls extends BaseReader
     /**
      * Read HCENTER record.
      */
-    private function readHcenter()
+    private function readHcenter(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3325,7 +3325,7 @@ class Xls extends BaseReader
     /**
      * Read VCENTER record.
      */
-    private function readVcenter()
+    private function readVcenter(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3344,7 +3344,7 @@ class Xls extends BaseReader
     /**
      * Read LEFTMARGIN record.
      */
-    private function readLeftMargin()
+    private function readLeftMargin(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3361,7 +3361,7 @@ class Xls extends BaseReader
     /**
      * Read RIGHTMARGIN record.
      */
-    private function readRightMargin()
+    private function readRightMargin(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3378,7 +3378,7 @@ class Xls extends BaseReader
     /**
      * Read TOPMARGIN record.
      */
-    private function readTopMargin()
+    private function readTopMargin(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3395,7 +3395,7 @@ class Xls extends BaseReader
     /**
      * Read BOTTOMMARGIN record.
      */
-    private function readBottomMargin()
+    private function readBottomMargin(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3412,7 +3412,7 @@ class Xls extends BaseReader
     /**
      * Read PAGESETUP record.
      */
-    private function readPageSetup()
+    private function readPageSetup(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3475,7 +3475,7 @@ class Xls extends BaseReader
      * PROTECT - Sheet protection (BIFF2 through BIFF8)
      *   if this record is omitted, then it also means no sheet protection.
      */
-    private function readProtect()
+    private function readProtect(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3497,7 +3497,7 @@ class Xls extends BaseReader
     /**
      * SCENPROTECT.
      */
-    private function readScenProtect()
+    private function readScenProtect(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3520,7 +3520,7 @@ class Xls extends BaseReader
     /**
      * OBJECTPROTECT.
      */
-    private function readObjectProtect()
+    private function readObjectProtect(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3543,7 +3543,7 @@ class Xls extends BaseReader
     /**
      * PASSWORD - Sheet protection (hashed) password (BIFF2 through BIFF8).
      */
-    private function readPassword()
+    private function readPassword(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3561,7 +3561,7 @@ class Xls extends BaseReader
     /**
      * Read DEFCOLWIDTH record.
      */
-    private function readDefColWidth()
+    private function readDefColWidth(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3579,7 +3579,7 @@ class Xls extends BaseReader
     /**
      * Read COLINFO record.
      */
-    private function readColInfo()
+    private function readColInfo(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3637,7 +3637,7 @@ class Xls extends BaseReader
      * --    "OpenOffice.org's Documentation of the Microsoft
      *         Excel File Format"
      */
-    private function readRow()
+    private function readRow(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3706,7 +3706,7 @@ class Xls extends BaseReader
      * --    "OpenOffice.org's Documentation of the Microsoft
      *         Excel File Format"
      */
-    private function readRk()
+    private function readRk(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3750,7 +3750,7 @@ class Xls extends BaseReader
      * --    "OpenOffice.org's Documentation of the Microsoft
      *         Excel File Format"
      */
-    private function readLabelSst()
+    private function readLabelSst(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3834,7 +3834,7 @@ class Xls extends BaseReader
      * --    "OpenOffice.org's Documentation of the Microsoft
      *         Excel File Format"
      */
-    private function readMulRk()
+    private function readMulRk(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3887,7 +3887,7 @@ class Xls extends BaseReader
      * --    "OpenOffice.org's Documentation of the Microsoft
      *         Excel File Format"
      */
-    private function readNumber()
+    private function readNumber(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -3928,7 +3928,7 @@ class Xls extends BaseReader
      * --    "OpenOffice.org's Documentation of the Microsoft
      *         Excel File Format"
      */
-    private function readFormula()
+    private function readFormula(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -4054,7 +4054,7 @@ class Xls extends BaseReader
      * which usually contains relative references.
      * These will be used to construct the formula in each shared formula part after the sheet is read.
      */
-    private function readSharedFmla()
+    private function readSharedFmla(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -4112,7 +4112,7 @@ class Xls extends BaseReader
      * --    "OpenOffice.org's Documentation of the Microsoft
      *         Excel File Format"
      */
-    private function readBoolErr()
+    private function readBoolErr(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -4171,7 +4171,7 @@ class Xls extends BaseReader
      * --    "OpenOffice.org's Documentation of the Microsoft
      *         Excel File Format"
      */
-    private function readMulBlank()
+    private function readMulBlank(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -4212,7 +4212,7 @@ class Xls extends BaseReader
      * --    "OpenOffice.org's Documentation of the Microsoft
      *         Excel File Format"
      */
-    private function readLabel()
+    private function readLabel(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -4256,7 +4256,7 @@ class Xls extends BaseReader
     /**
      * Read BLANK record.
      */
-    private function readBlank()
+    private function readBlank(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -4286,7 +4286,7 @@ class Xls extends BaseReader
     /**
      * Read MSODRAWING record.
      */
-    private function readMsoDrawing()
+    private function readMsoDrawing(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
 
@@ -4300,7 +4300,7 @@ class Xls extends BaseReader
     /**
      * Read OBJ record.
      */
-    private function readObj()
+    private function readObj(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -4340,7 +4340,7 @@ class Xls extends BaseReader
     /**
      * Read WINDOW2 record.
      */
-    private function readWindow2()
+    private function readWindow2(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -4411,7 +4411,7 @@ class Xls extends BaseReader
     /**
      * Read PLV Record(Created by Excel2007 or upper).
      */
-    private function readPageLayoutView()
+    private function readPageLayoutView(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -4448,7 +4448,7 @@ class Xls extends BaseReader
     /**
      * Read SCL record.
      */
-    private function readScl()
+    private function readScl(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -4469,7 +4469,7 @@ class Xls extends BaseReader
     /**
      * Read PANE record.
      */
-    private function readPane()
+    private function readPane(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -4503,7 +4503,7 @@ class Xls extends BaseReader
     /**
      * Read SELECTION record. There is one such record for each pane in the sheet.
      */
-    private function readSelection()
+    private function readSelection(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -4580,7 +4580,7 @@ class Xls extends BaseReader
      * --    "OpenOffice.org's Documentation of the Microsoft
      *         Excel File Format"
      */
-    private function readMergedCells()
+    private function readMergedCells(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -4602,7 +4602,7 @@ class Xls extends BaseReader
     /**
      * Read HYPERLINK record.
      */
-    private function readHyperLink()
+    private function readHyperLink(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -4775,7 +4775,7 @@ class Xls extends BaseReader
     /**
      * Read DATAVALIDATIONS record.
      */
-    private function readDataValidations()
+    private function readDataValidations(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -4787,7 +4787,7 @@ class Xls extends BaseReader
     /**
      * Read DATAVALIDATION record.
      */
-    private function readDataValidation()
+    private function readDataValidation(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -4997,7 +4997,7 @@ class Xls extends BaseReader
     /**
      * Read SHEETLAYOUT record. Stores sheet tab color information.
      */
-    private function readSheetLayout()
+    private function readSheetLayout(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -5037,7 +5037,7 @@ class Xls extends BaseReader
     /**
      * Read SHEETPROTECTION record (FEATHEADR).
      */
-    private function readSheetProtection()
+    private function readSheetProtection(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -5137,7 +5137,7 @@ class Xls extends BaseReader
      * Reading of this record is based on Microsoft Office Excel 97-2000 Binary File Format Specification,
      * where it is referred to as FEAT record.
      */
-    private function readRangeProtection()
+    private function readRangeProtection(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -5199,7 +5199,7 @@ class Xls extends BaseReader
      * When MSODRAWING data on a sheet exceeds 8224 bytes, CONTINUE records are used instead. Undocumented.
      * In this case, we must treat the CONTINUE record as a MSODRAWING record.
      */
-    private function readContinue()
+    private function readContinue(): void
     {
         $length = self::getUInt2d($this->data, $this->pos + 2);
         $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
@@ -5319,7 +5319,7 @@ class Xls extends BaseReader
         // start parsing the formula data
         $tokens = [];
 
-        while (strlen($formulaData) > 0 and $token = $this->getNextToken($formulaData, $baseCell)) {
+        while (strlen($formulaData) > 0 && $token = $this->getNextToken($formulaData, $baseCell)) {
             $tokens[] = $token;
             $formulaData = substr($formulaData, $token['size']);
         }
@@ -7203,7 +7203,7 @@ class Xls extends BaseReader
         $fc = Coordinate::stringFromColumnIndex($fc + 1);
         $lc = Coordinate::stringFromColumnIndex($lc + 1);
 
-        if ($fr == $lr and $fc == $lc) {
+        if ($fr == $lr && $fc == $lc) {
             return "$fc$fr";
         }
 
@@ -7242,7 +7242,7 @@ class Xls extends BaseReader
         $fc = Coordinate::stringFromColumnIndex($fc + 1);
         $lc = Coordinate::stringFromColumnIndex($lc + 1);
 
-        if ($fr == $lr and $fc == $lc) {
+        if ($fr == $lr && $fc == $lc) {
             return "$fc$fr";
         }
 
@@ -7463,7 +7463,7 @@ class Xls extends BaseReader
             switch ($type) {
                 case 'internal':
                     // check if we have a deleted 3d reference
-                    if ($this->ref[$index]['firstSheetIndex'] == 0xFFFF or $this->ref[$index]['lastSheetIndex'] == 0xFFFF) {
+                    if ($this->ref[$index]['firstSheetIndex'] == 0xFFFF || $this->ref[$index]['lastSheetIndex'] == 0xFFFF) {
                         throw new Exception('Deleted sheet reference');
                     }
 
@@ -7688,7 +7688,7 @@ class Xls extends BaseReader
         $string = self::readUnicodeString(substr($subData, 1), $characterCount);
 
         // add 1 for the string length
-        $string['size'] += 1;
+        ++$string['size'];
 
         return $string;
     }
@@ -7781,13 +7781,13 @@ class Xls extends BaseReader
         $mantissa = (0x100000 | ($rknumhigh & 0x000fffff));
         $mantissalow1 = ($rknumlow & 0x80000000) >> 31;
         $mantissalow2 = ($rknumlow & 0x7fffffff);
-        $value = $mantissa / pow(2, (20 - $exp));
+        $value = $mantissa / 2 ** (20 - $exp);
 
         if ($mantissalow1 != 0) {
-            $value += 1 / pow(2, (21 - $exp));
+            $value += 1 / 2 ** (21 - $exp);
         }
 
-        $value += $mantissalow2 / pow(2, (52 - $exp));
+        $value += $mantissalow2 / 2 ** (52 - $exp);
         if ($sign) {
             $value *= -1;
         }
@@ -7813,7 +7813,7 @@ class Xls extends BaseReader
             $sign = ($rknum & 0x80000000) >> 31;
             $exp = ($rknum & 0x7ff00000) >> 20;
             $mantissa = (0x100000 | ($rknum & 0x000ffffc));
-            $value = $mantissa / pow(2, (20 - ($exp - 1023)));
+            $value = $mantissa / 2 ** (20 - ($exp - 1023));
             if ($sign) {
                 $value = -1 * $value;
             }

src/PhpSpreadsheet/Reader/Xls/Escher.php

@@ -178,7 +178,7 @@ class Escher
     /**
      * Read a generic record.
      */
-    private function readDefault()
+    private function readDefault(): void
     {
         // offset 0; size: 2; recVer and recInstance
         $verInstance = Xls::getUInt2d($this->data, $this->pos);
@@ -199,7 +199,7 @@ class Escher
     /**
      * Read DggContainer record (Drawing Group Container).
      */
-    private function readDggContainer()
+    private function readDggContainer(): void
     {
         $length = Xls::getInt4d($this->data, $this->pos + 4);
         $recordData = substr($this->data, $this->pos + 8, $length);
@@ -217,7 +217,7 @@ class Escher
     /**
      * Read Dgg record (Drawing Group).
      */
-    private function readDgg()
+    private function readDgg(): void
     {
         $length = Xls::getInt4d($this->data, $this->pos + 4);
         $recordData = substr($this->data, $this->pos + 8, $length);
@@ -229,7 +229,7 @@ class Escher
     /**
      * Read BstoreContainer record (Blip Store Container).
      */
-    private function readBstoreContainer()
+    private function readBstoreContainer(): void
     {
         $length = Xls::getInt4d($this->data, $this->pos + 4);
         $recordData = substr($this->data, $this->pos + 8, $length);
@@ -247,7 +247,7 @@ class Escher
     /**
      * Read BSE record.
      */
-    private function readBSE()
+    private function readBSE(): void
     {
         // offset: 0; size: 2; recVer and recInstance
 
@@ -313,7 +313,7 @@ class Escher
     /**
      * Read BlipJPEG record. Holds raw JPEG image data.
      */
-    private function readBlipJPEG()
+    private function readBlipJPEG(): void
     {
         // offset: 0; size: 2; recVer and recInstance
 
@@ -340,7 +340,7 @@ class Escher
 
         // offset: var; size: 1; tag
         $tag = ord($recordData[$pos]);
-        $pos += 1;
+        ++$pos;
 
         // offset: var; size: var; the raw image data
         $data = substr($recordData, $pos);
@@ -354,7 +354,7 @@ class Escher
     /**
      * Read BlipPNG record. Holds raw PNG image data.
      */
-    private function readBlipPNG()
+    private function readBlipPNG(): void
     {
         // offset: 0; size: 2; recVer and recInstance
 
@@ -381,7 +381,7 @@ class Escher
 
         // offset: var; size: 1; tag
         $tag = ord($recordData[$pos]);
-        $pos += 1;
+        ++$pos;
 
         // offset: var; size: var; the raw image data
         $data = substr($recordData, $pos);
@@ -395,7 +395,7 @@ class Escher
     /**
      * Read OPT record. This record may occur within DggContainer record or SpContainer.
      */
-    private function readOPT()
+    private function readOPT(): void
     {
         // offset: 0; size: 2; recVer and recInstance
 
@@ -414,7 +414,7 @@ class Escher
     /**
      * Read TertiaryOPT record.
      */
-    private function readTertiaryOPT()
+    private function readTertiaryOPT(): void
     {
         // offset: 0; size: 2; recVer and recInstance
 
@@ -431,7 +431,7 @@ class Escher
     /**
      * Read SplitMenuColors record.
      */
-    private function readSplitMenuColors()
+    private function readSplitMenuColors(): void
     {
         $length = Xls::getInt4d($this->data, $this->pos + 4);
         $recordData = substr($this->data, $this->pos + 8, $length);
@@ -443,7 +443,7 @@ class Escher
     /**
      * Read DgContainer record (Drawing Container).
      */
-    private function readDgContainer()
+    private function readDgContainer(): void
     {
         $length = Xls::getInt4d($this->data, $this->pos + 4);
         $recordData = substr($this->data, $this->pos + 8, $length);
@@ -461,7 +461,7 @@ class Escher
     /**
      * Read Dg record (Drawing).
      */
-    private function readDg()
+    private function readDg(): void
     {
         $length = Xls::getInt4d($this->data, $this->pos + 4);
         $recordData = substr($this->data, $this->pos + 8, $length);
@@ -473,7 +473,7 @@ class Escher
     /**
      * Read SpgrContainer record (Shape Group Container).
      */
-    private function readSpgrContainer()
+    private function readSpgrContainer(): void
     {
         // context is either context DgContainer or SpgrContainer
 
@@ -501,7 +501,7 @@ class Escher
     /**
      * Read SpContainer record (Shape Container).
      */
-    private function readSpContainer()
+    private function readSpContainer(): void
     {
         $length = Xls::getInt4d($this->data, $this->pos + 4);
         $recordData = substr($this->data, $this->pos + 8, $length);
@@ -521,7 +521,7 @@ class Escher
     /**
      * Read Spgr record (Shape Group).
      */
-    private function readSpgr()
+    private function readSpgr(): void
     {
         $length = Xls::getInt4d($this->data, $this->pos + 4);
         $recordData = substr($this->data, $this->pos + 8, $length);
@@ -533,7 +533,7 @@ class Escher
     /**
      * Read Sp record (Shape).
      */
-    private function readSp()
+    private function readSp(): void
     {
         // offset: 0; size: 2; recVer and recInstance
 
@@ -550,7 +550,7 @@ class Escher
     /**
      * Read ClientTextbox record.
      */
-    private function readClientTextbox()
+    private function readClientTextbox(): void
     {
         // offset: 0; size: 2; recVer and recInstance
 
@@ -567,7 +567,7 @@ class Escher
     /**
      * Read ClientAnchor record. This record holds information about where the shape is anchored in worksheet.
      */
-    private function readClientAnchor()
+    private function readClientAnchor(): void
     {
         $length = Xls::getInt4d($this->data, $this->pos + 4);
         $recordData = substr($this->data, $this->pos + 8, $length);
@@ -621,7 +621,7 @@ class Escher
     /**
      * Read ClientData record.
      */
-    private function readClientData()
+    private function readClientData(): void
     {
         $length = Xls::getInt4d($this->data, $this->pos + 4);
         $recordData = substr($this->data, $this->pos + 8, $length);
@@ -636,7 +636,7 @@ class Escher
      * @param string $data Binary data
      * @param int $n Number of properties
      */
-    private function readOfficeArtRGFOPTE($data, $n)
+    private function readOfficeArtRGFOPTE($data, $n): void
     {
         $splicedComplexData = substr($data, 6 * $n);
 

src/PhpSpreadsheet/Reader/Xls/MD5.php

@@ -24,7 +24,7 @@ class MD5
     /**
      * Reset the MD5 stream context.
      */
-    public function reset()
+    public function reset(): void
     {
         $this->a = 0x67452301;
         $this->b = 0xEFCDAB89;
@@ -56,7 +56,7 @@ class MD5
      *
      * @param string $data Data to add
      */
-    public function add($data)
+    public function add($data): void
     {
         $words = array_values(unpack('V16', $data));
 
@@ -168,7 +168,7 @@ class MD5
         return $Y ^ ($X | (~$Z)); // Y XOR (X OR NOT Z)
     }
 
-    private static function step($func, &$A, $B, $C, $D, $M, $s, $t)
+    private static function step($func, &$A, $B, $C, $D, $M, $s, $t): void
     {
         $A = ($A + call_user_func($func, $B, $C, $D) + $M + $t) & 0xffffffff;
         $A = self::rotate($A, $s);

src/PhpSpreadsheet/Reader/Xlsx.php

@@ -35,6 +35,8 @@ use PhpOffice\PhpSpreadsheet\Style\Style;
 use PhpOffice\PhpSpreadsheet\Worksheet\HeaderFooterDrawing;
 use PhpOffice\PhpSpreadsheet\Worksheet\Worksheet;
 use SimpleXMLElement;
+use stdClass;
+use Throwable;
 use XMLReader;
 use ZipArchive;
 
@@ -256,7 +258,7 @@ class Xlsx extends BaseReader
         return isset($c->v) ? (string) $c->v : null;
     }
 
-    private function castToFormula($c, $r, &$cellDataType, &$value, &$calculatedValue, &$sharedFormulas, $castBaseType)
+    private function castToFormula($c, $r, &$cellDataType, &$value, &$calculatedValue, &$sharedFormulas, $castBaseType): void
     {
         $cellDataType = 'f';
         $value = "={$c->f}";
@@ -282,7 +284,6 @@ class Xlsx extends BaseReader
     }
 
     /**
-     * @param ZipArchive $archive
      * @param string $fileName
      *
      * @return string
@@ -658,7 +659,7 @@ class Xlsx extends BaseReader
                                             $coordinates = Coordinate::coordinateFromString($r);
 
                                             if (!$this->getReadFilter()->readCell($coordinates[0], (int) $coordinates[1], $docSheet->getTitle())) {
-                                                $rowIndex += 1;
+                                                ++$rowIndex;
 
                                                 continue;
                                             }
@@ -744,9 +745,9 @@ class Xlsx extends BaseReader
                                                     (int) ($c['s']) : 0);
                                             }
                                         }
-                                        $rowIndex += 1;
+                                        ++$rowIndex;
                                     }
-                                    $cIndex += 1;
+                                    ++$cIndex;
                                 }
                             }
 
@@ -891,7 +892,7 @@ class Xlsx extends BaseReader
                                             Settings::getLibXmlLoaderOptions()
                                         );
                                         $vmlCommentsFile->registerXPathNamespace('v', 'urn:schemas-microsoft-com:vml');
-                                    } catch (\Throwable $ex) {
+                                    } catch (Throwable $ex) {
                                         //Ignore unparsable vmlDrawings. Later they will be moved from $unparsedVmlDrawings to $unparsedLoadedData
                                         continue;
                                     }
@@ -1115,7 +1116,7 @@ class Xlsx extends BaseReader
                                                     $xfrm = $oneCellAnchor->pic->spPr->children('http://schemas.openxmlformats.org/drawingml/2006/main')->xfrm;
                                                     /** @var SimpleXMLElement $outerShdw */
                                                     $outerShdw = $oneCellAnchor->pic->spPr->children('http://schemas.openxmlformats.org/drawingml/2006/main')->effectLst->outerShdw;
-                                                    /** @var \SimpleXMLElement $hlinkClick */
+                                                    /** @var SimpleXMLElement $hlinkClick */
                                                     $hlinkClick = $oneCellAnchor->pic->nvPicPr->cNvPr->children('http://schemas.openxmlformats.org/drawingml/2006/main')->hlinkClick;
 
                                                     $objDrawing = new \PhpOffice\PhpSpreadsheet\Worksheet\Drawing();
@@ -1556,10 +1557,9 @@ class Xlsx extends BaseReader
     }
 
     /**
-     * @param Style $docStyle
+     * @param SimpleXMLElement|stdClass $style
-     * @param SimpleXMLElement|\stdClass $style
      */
-    private static function readStyle(Style $docStyle, $style)
+    private static function readStyle(Style $docStyle, $style): void
     {
         $docStyle->getNumberFormat()->setFormatCode($style->numFmt);
 
@@ -1684,10 +1684,9 @@ class Xlsx extends BaseReader
     }
 
     /**
-     * @param Border $docBorder
      * @param SimpleXMLElement $eleBorder
      */
-    private static function readBorder(Border $docBorder, $eleBorder)
+    private static function readBorder(Border $docBorder, $eleBorder): void
     {
         if (isset($eleBorder['style'])) {
             $docBorder->setBorderStyle((string) $eleBorder['style']);
@@ -1760,11 +1759,10 @@ class Xlsx extends BaseReader
     }
 
     /**
-     * @param Spreadsheet $excel
      * @param mixed $customUITarget
      * @param mixed $zip
      */
-    private function readRibbon(Spreadsheet $excel, $customUITarget, $zip)
+    private function readRibbon(Spreadsheet $excel, $customUITarget, $zip): void
     {
         $baseDir = dirname($customUITarget);
         $nameCustomUI = basename($customUITarget);
@@ -1866,10 +1864,10 @@ class Xlsx extends BaseReader
 
     /**
      * @param \PhpOffice\PhpSpreadsheet\Worksheet\Drawing $objDrawing
-     * @param \SimpleXMLElement $cellAnchor
+     * @param SimpleXMLElement $cellAnchor
      * @param array $hyperlinks
      */
-    private function readHyperLinkDrawing($objDrawing, $cellAnchor, $hyperlinks)
+    private function readHyperLinkDrawing($objDrawing, $cellAnchor, $hyperlinks): void
     {
         $hlinkClick = $cellAnchor->pic->nvPicPr->cNvPr->children('http://schemas.openxmlformats.org/drawingml/2006/main')->hlinkClick;
 
@@ -1885,7 +1883,7 @@ class Xlsx extends BaseReader
         $objDrawing->setHyperlink($hyperlink);
     }
 
-    private function readProtection(Spreadsheet $excel, SimpleXMLElement $xmlWorkbook)
+    private function readProtection(Spreadsheet $excel, SimpleXMLElement $xmlWorkbook): void
     {
         if (!$xmlWorkbook->workbookProtection) {
             return;
@@ -1912,7 +1910,7 @@ class Xlsx extends BaseReader
         }
     }
 
-    private function readFormControlProperties(Spreadsheet $excel, ZipArchive $zip, $dir, $fileWorksheet, $docSheet, array &$unparsedLoadedData)
+    private function readFormControlProperties(Spreadsheet $excel, ZipArchive $zip, $dir, $fileWorksheet, $docSheet, array &$unparsedLoadedData): void
     {
         if (!$zip->locateName(dirname("$dir/$fileWorksheet") . '/_rels/' . basename($fileWorksheet) . '.rels')) {
             return;
@@ -1944,7 +1942,7 @@ class Xlsx extends BaseReader
         unset($unparsedCtrlProps);
     }
 
-    private function readPrinterSettings(Spreadsheet $excel, ZipArchive $zip, $dir, $fileWorksheet, $docSheet, array &$unparsedLoadedData)
+    private function readPrinterSettings(Spreadsheet $excel, ZipArchive $zip, $dir, $fileWorksheet, $docSheet, array &$unparsedLoadedData): void
     {
         if (!$zip->locateName(dirname("$dir/$fileWorksheet") . '/_rels/' . basename($fileWorksheet) . '.rels')) {
             return;

src/PhpSpreadsheet/Reader/Xlsx/AutoFilter.php

@@ -5,6 +5,7 @@ namespace PhpOffice\PhpSpreadsheet\Reader\Xlsx;
 use PhpOffice\PhpSpreadsheet\Worksheet\AutoFilter\Column;
 use PhpOffice\PhpSpreadsheet\Worksheet\AutoFilter\Column\Rule;
 use PhpOffice\PhpSpreadsheet\Worksheet\Worksheet;
+use SimpleXMLElement;
 
 class AutoFilter
 {
@@ -12,13 +13,13 @@ class AutoFilter
 
     private $worksheetXml;
 
-    public function __construct(Worksheet $workSheet, \SimpleXMLElement $worksheetXml)
+    public function __construct(Worksheet $workSheet, SimpleXMLElement $worksheetXml)
     {
         $this->worksheet = $workSheet;
         $this->worksheetXml = $worksheetXml;
     }
 
-    public function load()
+    public function load(): void
     {
         // Remove all "$" in the auto filter range
         $autoFilterRange = preg_replace('/\$/', '', $this->worksheetXml->autoFilter['ref']);
@@ -27,7 +28,7 @@ class AutoFilter
         }
     }
 
-    private function readAutoFilter($autoFilterRange, $xmlSheet)
+    private function readAutoFilter($autoFilterRange, $xmlSheet): void
     {
         $autoFilter = $this->worksheet->getAutoFilter();
         $autoFilter->setRange($autoFilterRange);
@@ -62,7 +63,7 @@ class AutoFilter
         }
     }
 
-    private function readDateRangeAutoFilter(\SimpleXMLElement $filters, Column $column)
+    private function readDateRangeAutoFilter(SimpleXMLElement $filters, Column $column): void
     {
         foreach ($filters->dateGroupItem as $dateGroupItem) {
             //    Operator is undefined, but always treated as EQUAL
@@ -81,7 +82,7 @@ class AutoFilter
         }
     }
 
-    private function readCustomAutoFilter(\SimpleXMLElement $filterColumn, Column $column)
+    private function readCustomAutoFilter(SimpleXMLElement $filterColumn, Column $column): void
     {
         if ($filterColumn->customFilters) {
             $column->setFilterType(Column::AUTOFILTER_FILTERTYPE_CUSTOMFILTER);
@@ -100,7 +101,7 @@ class AutoFilter
         }
     }
 
-    private function readDynamicAutoFilter(\SimpleXMLElement $filterColumn, Column $column)
+    private function readDynamicAutoFilter(SimpleXMLElement $filterColumn, Column $column): void
     {
         if ($filterColumn->dynamicFilter) {
             $column->setFilterType(Column::AUTOFILTER_FILTERTYPE_DYNAMICFILTER);
@@ -122,7 +123,7 @@ class AutoFilter
         }
     }
 
-    private function readTopTenAutoFilter(\SimpleXMLElement $filterColumn, Column $column)
+    private function readTopTenAutoFilter(SimpleXMLElement $filterColumn, Column $column): void
     {
         if ($filterColumn->top10) {
             $column->setFilterType(Column::AUTOFILTER_FILTERTYPE_TOPTENFILTER);

src/PhpSpreadsheet/Reader/Xlsx/Chart.php

@@ -17,7 +17,6 @@ use SimpleXMLElement;
 class Chart
 {
     /**
-     * @param SimpleXMLElement $component
      * @param string $name
      * @param string $format
      *
@@ -51,7 +50,6 @@ class Chart
     }
 
     /**
-     * @param SimpleXMLElement $chartElements
      * @param string $chartName
      *
      * @return \PhpOffice\PhpSpreadsheet\Chart\Chart
@@ -529,10 +527,9 @@ class Chart
     }
 
     /**
-     * @param Layout $plotArea
      * @param mixed $plotAttributes
      */
-    private static function setChartAttributes(Layout $plotArea, $plotAttributes)
+    private static function setChartAttributes(Layout $plotArea, $plotAttributes): void
     {
         foreach ($plotAttributes as $plotAttributeKey => $plotAttributeValue) {
             switch ($plotAttributeKey) {

src/PhpSpreadsheet/Reader/Xlsx/ColumnAndRowAttributes.php

@@ -5,6 +5,7 @@ namespace PhpOffice\PhpSpreadsheet\Reader\Xlsx;
 use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
 use PhpOffice\PhpSpreadsheet\Reader\IReadFilter;
 use PhpOffice\PhpSpreadsheet\Worksheet\Worksheet;
+use SimpleXMLElement;
 
 class ColumnAndRowAttributes extends BaseParserClass
 {
@@ -12,7 +13,7 @@ class ColumnAndRowAttributes extends BaseParserClass
 
     private $worksheetXml;
 
-    public function __construct(Worksheet $workSheet, \SimpleXMLElement $worksheetXml = null)
+    public function __construct(Worksheet $workSheet, ?SimpleXMLElement $worksheetXml = null)
     {
         $this->worksheet = $workSheet;
         $this->worksheetXml = $worksheetXml;
@@ -25,7 +26,7 @@ class ColumnAndRowAttributes extends BaseParserClass
      * @param array $columnAttributes array of attributes (indexes are attribute name, values are value)
      *                               'xfIndex', 'visible', 'collapsed', 'outlineLevel', 'width', ... ?
      */
-    private function setColumnAttributes($columnAddress, array $columnAttributes)
+    private function setColumnAttributes($columnAddress, array $columnAttributes): void
     {
         if (isset($columnAttributes['xfIndex'])) {
             $this->worksheet->getColumnDimension($columnAddress)->setXfIndex($columnAttributes['xfIndex']);
@@ -51,7 +52,7 @@ class ColumnAndRowAttributes extends BaseParserClass
      * @param array $rowAttributes array of attributes (indexes are attribute name, values are value)
      *                               'xfIndex', 'visible', 'collapsed', 'outlineLevel', 'rowHeight', ... ?
      */
-    private function setRowAttributes($rowNumber, array $rowAttributes)
+    private function setRowAttributes($rowNumber, array $rowAttributes): void
     {
         if (isset($rowAttributes['xfIndex'])) {
             $this->worksheet->getRowDimension($rowNumber)->setXfIndex($rowAttributes['xfIndex']);
@@ -74,7 +75,7 @@ class ColumnAndRowAttributes extends BaseParserClass
      * @param IReadFilter $readFilter
      * @param bool $readDataOnly
      */
-    public function load(IReadFilter $readFilter = null, $readDataOnly = false)
+    public function load(?IReadFilter $readFilter = null, $readDataOnly = false): void
     {
         if ($this->worksheetXml === null) {
             return;
@@ -125,7 +126,7 @@ class ColumnAndRowAttributes extends BaseParserClass
         return false;
     }
 
-    private function readColumnAttributes(\SimpleXMLElement $worksheetCols, $readDataOnly)
+    private function readColumnAttributes(SimpleXMLElement $worksheetCols, $readDataOnly)
     {
         $columnAttributes = [];
 
@@ -145,7 +146,7 @@ class ColumnAndRowAttributes extends BaseParserClass
         return $columnAttributes;
     }
 
-    private function readColumnRangeAttributes(\SimpleXMLElement $column, $readDataOnly)
+    private function readColumnRangeAttributes(SimpleXMLElement $column, $readDataOnly)
     {
         $columnAttributes = [];
 
@@ -177,7 +178,7 @@ class ColumnAndRowAttributes extends BaseParserClass
         return false;
     }
 
-    private function readRowAttributes(\SimpleXMLElement $worksheetRow, $readDataOnly)
+    private function readRowAttributes(SimpleXMLElement $worksheetRow, $readDataOnly)
     {
         $rowAttributes = [];
 

src/PhpSpreadsheet/Reader/Xlsx/ConditionalStyles.php

@@ -4,6 +4,7 @@ namespace PhpOffice\PhpSpreadsheet\Reader\Xlsx;
 
 use PhpOffice\PhpSpreadsheet\Style\Conditional;
 use PhpOffice\PhpSpreadsheet\Worksheet\Worksheet;
+use SimpleXMLElement;
 
 class ConditionalStyles
 {
@@ -13,14 +14,14 @@ class ConditionalStyles
 
     private $dxfs;
 
-    public function __construct(Worksheet $workSheet, \SimpleXMLElement $worksheetXml, array $dxfs = [])
+    public function __construct(Worksheet $workSheet, SimpleXMLElement $worksheetXml, array $dxfs = [])
     {
         $this->worksheet = $workSheet;
         $this->worksheetXml = $worksheetXml;
         $this->dxfs = $dxfs;
     }
 
-    public function load()
+    public function load(): void
     {
         $this->setConditionalStyles(
             $this->worksheet,
@@ -48,7 +49,7 @@ class ConditionalStyles
         return $conditionals;
     }
 
-    private function setConditionalStyles(Worksheet $worksheet, array $conditionals)
+    private function setConditionalStyles(Worksheet $worksheet, array $conditionals): void
     {
         foreach ($conditionals as $ref => $cfRules) {
             ksort($cfRules);

src/PhpSpreadsheet/Reader/Xlsx/DataValidations.php

@@ -4,6 +4,7 @@ namespace PhpOffice\PhpSpreadsheet\Reader\Xlsx;
 
 use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
 use PhpOffice\PhpSpreadsheet\Worksheet\Worksheet;
+use SimpleXMLElement;
 
 class DataValidations
 {
@@ -11,13 +12,13 @@ class DataValidations
 
     private $worksheetXml;
 
-    public function __construct(Worksheet $workSheet, \SimpleXMLElement $worksheetXml)
+    public function __construct(Worksheet $workSheet, SimpleXMLElement $worksheetXml)
     {
         $this->worksheet = $workSheet;
         $this->worksheetXml = $worksheetXml;
     }
 
-    public function load()
+    public function load(): void
     {
         foreach ($this->worksheetXml->dataValidations->dataValidation as $dataValidation) {
             // Uppercase coordinate

src/PhpSpreadsheet/Reader/Xlsx/Hyperlinks.php

@@ -4,6 +4,7 @@ namespace PhpOffice\PhpSpreadsheet\Reader\Xlsx;
 
 use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
 use PhpOffice\PhpSpreadsheet\Worksheet\Worksheet;
+use SimpleXMLElement;
 
 class Hyperlinks
 {
@@ -16,7 +17,7 @@ class Hyperlinks
         $this->worksheet = $workSheet;
     }
 
-    public function readHyperlinks(\SimpleXMLElement $relsWorksheet)
+    public function readHyperlinks(SimpleXMLElement $relsWorksheet): void
     {
         foreach ($relsWorksheet->Relationship as $element) {
             if ($element['Type'] == 'http://schemas.openxmlformats.org/officeDocument/2006/relationships/hyperlink') {
@@ -25,14 +26,14 @@ class Hyperlinks
         }
     }
 
-    public function setHyperlinks(\SimpleXMLElement $worksheetXml)
+    public function setHyperlinks(SimpleXMLElement $worksheetXml): void
     {
         foreach ($worksheetXml->hyperlink as $hyperlink) {
             $this->setHyperlink($hyperlink, $this->worksheet);
         }
     }
 
-    private function setHyperlink(\SimpleXMLElement $hyperlink, Worksheet $worksheet)
+    private function setHyperlink(SimpleXMLElement $hyperlink, Worksheet $worksheet): void
     {
         // Link url
         $linkRel = $hyperlink->attributes('http://schemas.openxmlformats.org/officeDocument/2006/relationships');

src/PhpSpreadsheet/Reader/Xlsx/PageSetup.php

@@ -4,6 +4,7 @@ namespace PhpOffice\PhpSpreadsheet\Reader\Xlsx;
 
 use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
 use PhpOffice\PhpSpreadsheet\Worksheet\Worksheet;
+use SimpleXMLElement;
 
 class PageSetup extends BaseParserClass
 {
@@ -11,7 +12,7 @@ class PageSetup extends BaseParserClass
 
     private $worksheetXml;
 
-    public function __construct(Worksheet $workSheet, \SimpleXMLElement $worksheetXml = null)
+    public function __construct(Worksheet $workSheet, ?SimpleXMLElement $worksheetXml = null)
     {
         $this->worksheet = $workSheet;
         $this->worksheetXml = $worksheetXml;
@@ -31,7 +32,7 @@ class PageSetup extends BaseParserClass
         return $unparsedLoadedData;
     }
 
-    private function margins(\SimpleXMLElement $xmlSheet, Worksheet $worksheet)
+    private function margins(SimpleXMLElement $xmlSheet, Worksheet $worksheet): void
     {
         if ($xmlSheet->pageMargins) {
             $docPageMargins = $worksheet->getPageMargins();
@@ -44,7 +45,7 @@ class PageSetup extends BaseParserClass
         }
     }
 
-    private function pageSetup(\SimpleXMLElement $xmlSheet, Worksheet $worksheet, array $unparsedLoadedData)
+    private function pageSetup(SimpleXMLElement $xmlSheet, Worksheet $worksheet, array $unparsedLoadedData)
     {
         if ($xmlSheet->pageSetup) {
             $docPageSetup = $worksheet->getPageSetup();
@@ -78,7 +79,7 @@ class PageSetup extends BaseParserClass
         return $unparsedLoadedData;
     }
 
-    private function headerFooter(\SimpleXMLElement $xmlSheet, Worksheet $worksheet)
+    private function headerFooter(SimpleXMLElement $xmlSheet, Worksheet $worksheet): void
     {
         if ($xmlSheet->headerFooter) {
             $docHeaderFooter = $worksheet->getHeaderFooter();
@@ -117,7 +118,7 @@ class PageSetup extends BaseParserClass
         }
     }
 
-    private function pageBreaks(\SimpleXMLElement $xmlSheet, Worksheet $worksheet)
+    private function pageBreaks(SimpleXMLElement $xmlSheet, Worksheet $worksheet): void
     {
         if ($xmlSheet->rowBreaks && $xmlSheet->rowBreaks->brk) {
             $this->rowBreaks($xmlSheet, $worksheet);
@@ -127,7 +128,7 @@ class PageSetup extends BaseParserClass
         }
     }
 
-    private function rowBreaks(\SimpleXMLElement $xmlSheet, Worksheet $worksheet)
+    private function rowBreaks(SimpleXMLElement $xmlSheet, Worksheet $worksheet): void
     {
         foreach ($xmlSheet->rowBreaks->brk as $brk) {
             if ($brk['man']) {
@@ -136,7 +137,7 @@ class PageSetup extends BaseParserClass
         }
     }
 
-    private function columnBreaks(\SimpleXMLElement $xmlSheet, Worksheet $worksheet)
+    private function columnBreaks(SimpleXMLElement $xmlSheet, Worksheet $worksheet): void
     {
         foreach ($xmlSheet->colBreaks->brk as $brk) {
             if ($brk['man']) {

src/PhpSpreadsheet/Reader/Xlsx/Properties.php

@@ -5,6 +5,7 @@ namespace PhpOffice\PhpSpreadsheet\Reader\Xlsx;
 use PhpOffice\PhpSpreadsheet\Document\Properties as DocumentProperties;
 use PhpOffice\PhpSpreadsheet\Reader\Security\XmlScanner;
 use PhpOffice\PhpSpreadsheet\Settings;
+use SimpleXMLElement;
 
 class Properties
 {
@@ -27,7 +28,7 @@ class Properties
         );
     }
 
-    public function readCoreProperties($propertyData)
+    public function readCoreProperties($propertyData): void
     {
         $xmlCore = $this->extractPropertyData($propertyData);
 
@@ -48,7 +49,7 @@ class Properties
         }
     }
 
-    public function readExtendedProperties($propertyData)
+    public function readExtendedProperties($propertyData): void
     {
         $xmlCore = $this->extractPropertyData($propertyData);
 
@@ -62,13 +63,13 @@ class Properties
         }
     }
 
-    public function readCustomProperties($propertyData)
+    public function readCustomProperties($propertyData): void
     {
         $xmlCore = $this->extractPropertyData($propertyData);
 
         if (is_object($xmlCore)) {
             foreach ($xmlCore as $xmlProperty) {
-                /** @var \SimpleXMLElement $xmlProperty */
+                /** @var SimpleXMLElement $xmlProperty */
                 $cellDataOfficeAttributes = $xmlProperty->attributes();
                 if (isset($cellDataOfficeAttributes['name'])) {
                     $propertyName = (string) $cellDataOfficeAttributes['name'];

src/PhpSpreadsheet/Reader/Xlsx/SheetViewOptions.php

@@ -3,6 +3,7 @@
 namespace PhpOffice\PhpSpreadsheet\Reader\Xlsx;
 
 use PhpOffice\PhpSpreadsheet\Worksheet\Worksheet;
+use SimpleXMLElement;
 
 class SheetViewOptions extends BaseParserClass
 {
@@ -10,7 +11,7 @@ class SheetViewOptions extends BaseParserClass
 
     private $worksheetXml;
 
-    public function __construct(Worksheet $workSheet, \SimpleXMLElement $worksheetXml = null)
+    public function __construct(Worksheet $workSheet, ?SimpleXMLElement $worksheetXml = null)
     {
         $this->worksheet = $workSheet;
         $this->worksheetXml = $worksheetXml;
@@ -19,7 +20,7 @@ class SheetViewOptions extends BaseParserClass
     /**
      * @param bool $readDataOnly
      */
-    public function load($readDataOnly = false)
+    public function load($readDataOnly = false): void
     {
         if ($this->worksheetXml === null) {
             return;
@@ -41,21 +42,21 @@ class SheetViewOptions extends BaseParserClass
         }
     }
 
-    private function tabColor(\SimpleXMLElement $sheetPr)
+    private function tabColor(SimpleXMLElement $sheetPr): void
     {
         if (isset($sheetPr->tabColor, $sheetPr->tabColor['rgb'])) {
             $this->worksheet->getTabColor()->setARGB((string) $sheetPr->tabColor['rgb']);
         }
     }
 
-    private function codeName(\SimpleXMLElement $sheetPr)
+    private function codeName(SimpleXMLElement $sheetPr): void
     {
         if (isset($sheetPr['codeName'])) {
             $this->worksheet->setCodeName((string) $sheetPr['codeName'], false);
         }
     }
 
-    private function outlines(\SimpleXMLElement $sheetPr)
+    private function outlines(SimpleXMLElement $sheetPr): void
     {
         if (isset($sheetPr->outlinePr)) {
             if (isset($sheetPr->outlinePr['summaryRight']) &&
@@ -74,7 +75,7 @@ class SheetViewOptions extends BaseParserClass
         }
     }
 
-    private function pageSetup(\SimpleXMLElement $sheetPr)
+    private function pageSetup(SimpleXMLElement $sheetPr): void
     {
         if (isset($sheetPr->pageSetUpPr)) {
             if (isset($sheetPr->pageSetUpPr['fitToPage']) &&
@@ -86,7 +87,7 @@ class SheetViewOptions extends BaseParserClass
         }
     }
 
-    private function sheetFormat(\SimpleXMLElement $sheetFormatPr)
+    private function sheetFormat(SimpleXMLElement $sheetFormatPr): void
     {
         if (isset($sheetFormatPr['customHeight']) &&
             self::boolean((string) $sheetFormatPr['customHeight']) &&
@@ -106,7 +107,7 @@ class SheetViewOptions extends BaseParserClass
         }
     }
 
-    private function printOptions(\SimpleXMLElement $printOptions)
+    private function printOptions(SimpleXMLElement $printOptions): void
     {
         if (self::boolean((string) $printOptions['gridLinesSet'])) {
             $this->worksheet->setShowGridlines(true);

src/PhpSpreadsheet/Reader/Xlsx/SheetViews.php

@@ -4,6 +4,7 @@ namespace PhpOffice\PhpSpreadsheet\Reader\Xlsx;
 
 use PhpOffice\PhpSpreadsheet\Cell\Coordinate;
 use PhpOffice\PhpSpreadsheet\Worksheet\Worksheet;
+use SimpleXMLElement;
 
 class SheetViews extends BaseParserClass
 {
@@ -11,13 +12,13 @@ class SheetViews extends BaseParserClass
 
     private $worksheet;
 
-    public function __construct(\SimpleXMLElement $sheetViewXml, Worksheet $workSheet)
+    public function __construct(SimpleXMLElement $sheetViewXml, Worksheet $workSheet)
     {
         $this->sheetViewXml = $sheetViewXml;
         $this->worksheet = $workSheet;
     }
 
-    public function load()
+    public function load(): void
     {
         $this->zoomScale();
         $this->view();
@@ -34,7 +35,7 @@ class SheetViews extends BaseParserClass
         }
     }
 
-    private function zoomScale()
+    private function zoomScale(): void
     {
         if (isset($this->sheetViewXml['zoomScale'])) {
             $zoomScale = (int) ($this->sheetViewXml['zoomScale']);
@@ -59,14 +60,14 @@ class SheetViews extends BaseParserClass
         }
     }
 
-    private function view()
+    private function view(): void
     {
         if (isset($this->sheetViewXml['view'])) {
             $this->worksheet->getSheetView()->setView((string) $this->sheetViewXml['view']);
         }
     }
 
-    private function gridLines()
+    private function gridLines(): void
     {
         if (isset($this->sheetViewXml['showGridLines'])) {
             $this->worksheet->setShowGridLines(
@@ -75,7 +76,7 @@ class SheetViews extends BaseParserClass
         }
     }
 
-    private function headers()
+    private function headers(): void
     {
         if (isset($this->sheetViewXml['showRowColHeaders'])) {
             $this->worksheet->setShowRowColHeaders(
@@ -84,7 +85,7 @@ class SheetViews extends BaseParserClass
         }
     }
 
-    private function direction()
+    private function direction(): void
     {
         if (isset($this->sheetViewXml['rightToLeft'])) {
             $this->worksheet->setRightToLeft(
@@ -93,7 +94,7 @@ class SheetViews extends BaseParserClass
         }
     }
 
-    private function showZeros()
+    private function showZeros(): void
     {
         if (isset($this->sheetViewXml['showZeros'])) {
             $this->worksheet->getSheetView()->setShowZeros(
@@ -102,7 +103,7 @@ class SheetViews extends BaseParserClass
         }
     }
 
-    private function pane()
+    private function pane(): void
     {
         $xSplit = 0;
         $ySplit = 0;
@@ -126,7 +127,7 @@ class SheetViews extends BaseParserClass
         );
     }
 
-    private function selection()
+    private function selection(): void
     {
         $sqref = (string) $this->sheetViewXml->selection['sqref'];
         $sqref = explode(' ', $sqref);

src/PhpSpreadsheet/Reader/Xlsx/Styles.php

@@ -11,6 +11,7 @@ use PhpOffice\PhpSpreadsheet\Style\Font;
 use PhpOffice\PhpSpreadsheet\Style\NumberFormat;
 use PhpOffice\PhpSpreadsheet\Style\Protection;
 use PhpOffice\PhpSpreadsheet\Style\Style;
+use SimpleXMLElement;
 
 class Styles extends BaseParserClass
 {
@@ -27,19 +28,19 @@ class Styles extends BaseParserClass
 
     private $styleXml;
 
-    public function __construct(\SimpleXMLElement $styleXml)
+    public function __construct(SimpleXMLElement $styleXml)
     {
         $this->styleXml = $styleXml;
     }
 
-    public function setStyleBaseData(Theme $theme = null, $styles = [], $cellStyles = [])
+    public function setStyleBaseData(?Theme $theme = null, $styles = [], $cellStyles = []): void
     {
         self::$theme = $theme;
         $this->styles = $styles;
         $this->cellStyles = $cellStyles;
     }
 
-    private static function readFontStyle(Font $fontStyle, \SimpleXMLElement $fontStyleXml)
+    private static function readFontStyle(Font $fontStyle, SimpleXMLElement $fontStyleXml): void
     {
         $fontStyle->setName((string) $fontStyleXml->name['val']);
         $fontStyle->setSize((float) $fontStyleXml->sz['val']);
@@ -72,7 +73,7 @@ class Styles extends BaseParserClass
         }
     }
 
-    private static function readNumberFormat(NumberFormat $numfmtStyle, \SimpleXMLElement $numfmtStyleXml)
+    private static function readNumberFormat(NumberFormat $numfmtStyle, SimpleXMLElement $numfmtStyleXml): void
     {
         if ($numfmtStyleXml->count() === 0) {
             return;
@@ -83,10 +84,10 @@ class Styles extends BaseParserClass
         }
     }
 
-    private static function readFillStyle(Fill $fillStyle, \SimpleXMLElement $fillStyleXml)
+    private static function readFillStyle(Fill $fillStyle, SimpleXMLElement $fillStyleXml): void
     {
         if ($fillStyleXml->gradientFill) {
-            /** @var \SimpleXMLElement $gradientFill */
+            /** @var SimpleXMLElement $gradientFill */
             $gradientFill = $fillStyleXml->gradientFill[0];
             if (!empty($gradientFill['type'])) {
                 $fillStyle->setFillType((string) $gradientFill['type']);
@@ -109,7 +110,7 @@ class Styles extends BaseParserClass
         }
     }
 
-    private static function readBorderStyle(Borders $borderStyle, \SimpleXMLElement $borderStyleXml)
+    private static function readBorderStyle(Borders $borderStyle, SimpleXMLElement $borderStyleXml): void
     {
         $diagonalUp = self::boolean((string) $borderStyleXml['diagonalUp']);
         $diagonalDown = self::boolean((string) $borderStyleXml['diagonalDown']);
@@ -130,7 +131,7 @@ class Styles extends BaseParserClass
         self::readBorder($borderStyle->getDiagonal(), $borderStyleXml->diagonal);
     }
 
-    private static function readBorder(Border $border, \SimpleXMLElement $borderXml)
+    private static function readBorder(Border $border, SimpleXMLElement $borderXml): void
     {
         if (isset($borderXml['style'])) {
             $border->setBorderStyle((string) $borderXml['style']);
@@ -140,7 +141,7 @@ class Styles extends BaseParserClass
         }
     }
 
-    private static function readAlignmentStyle(Alignment $alignment, \SimpleXMLElement $alignmentXml)
+    private static function readAlignmentStyle(Alignment $alignment, SimpleXMLElement $alignmentXml): void
     {
         $alignment->setHorizontal((string) $alignmentXml->alignment['horizontal']);
         $alignment->setVertical((string) $alignmentXml->alignment['vertical']);
@@ -159,9 +160,9 @@ class Styles extends BaseParserClass
         $alignment->setReadOrder((int) ((string) $alignmentXml->alignment['readingOrder']) > 0 ? (int) ((string) $alignmentXml->alignment['readingOrder']) : 0);
     }
 
-    private function readStyle(Style $docStyle, $style)
+    private function readStyle(Style $docStyle, $style): void
     {
-        if ($style->numFmt instanceof \SimpleXMLElement) {
+        if ($style->numFmt instanceof SimpleXMLElement) {
             self::readNumberFormat($docStyle->getNumberFormat(), $style->numFmt);
         } else {
             $docStyle->getNumberFormat()->setFormatCode($style->numFmt);
@@ -195,7 +196,7 @@ class Styles extends BaseParserClass
         }
     }
 
-    private function readProtectionLocked(Style $docStyle, $style)
+    private function readProtectionLocked(Style $docStyle, $style): void
     {
         if (isset($style->protection['locked'])) {
             if (self::boolean((string) $style->protection['locked'])) {
@@ -206,7 +207,7 @@ class Styles extends BaseParserClass
         }
     }
 
-    private function readProtectionHidden(Style $docStyle, $style)
+    private function readProtectionHidden(Style $docStyle, $style): void
     {
         if (isset($style->protection['hidden'])) {
             if (self::boolean((string) $style->protection['hidden'])) {

src/PhpSpreadsheet/Reader/Xml.php

@@ -101,7 +101,7 @@ class Xml extends BaseReader
      *
      * @param string $pFilename
      *
-     * @return false|\SimpleXMLElement
+     * @return false|SimpleXMLElement
      */
     public function trySimpleXMLLoadString($pFilename)
     {
@@ -288,7 +288,6 @@ class Xml extends BaseReader
      * Loads from file into Spreadsheet instance.
      *
      * @param string $pFilename
-     * @param Spreadsheet $spreadsheet
      *
      * @return Spreadsheet
      */
@@ -653,11 +652,7 @@ class Xml extends BaseReader
         return $value;
     }
 
-    /**
+    private function parseStyles(SimpleXMLElement $xml, array $namespaces): void
-     * @param SimpleXMLElement $xml
-     * @param array $namespaces
-     */
-    private function parseStyles(SimpleXMLElement $xml, array $namespaces)
     {
         if (!isset($xml->Styles)) {
             return;
@@ -697,9 +692,8 @@ class Xml extends BaseReader
 
     /**
      * @param string $styleID
-     * @param SimpleXMLElement $styleAttributes
      */
-    private function parseStyleAlignment($styleID, SimpleXMLElement $styleAttributes)
+    private function parseStyleAlignment($styleID, SimpleXMLElement $styleAttributes): void
     {
         $verticalAlignmentStyles = [
             Alignment::VERTICAL_BOTTOM,
@@ -741,10 +735,8 @@ class Xml extends BaseReader
 
     /**
      * @param $styleID
-     * @param SimpleXMLElement $styleData
-     * @param array $namespaces
      */
-    private function parseStyleBorders($styleID, SimpleXMLElement $styleData, array $namespaces)
+    private function parseStyleBorders($styleID, SimpleXMLElement $styleData, array $namespaces): void
     {
         foreach ($styleData->Border as $borderStyle) {
             $borderAttributes = $borderStyle->attributes($namespaces['ss']);
@@ -778,9 +770,8 @@ class Xml extends BaseReader
 
     /**
      * @param $styleID
-     * @param SimpleXMLElement $styleAttributes
      */
-    private function parseStyleFont($styleID, SimpleXMLElement $styleAttributes)
+    private function parseStyleFont($styleID, SimpleXMLElement $styleAttributes): void
     {
         $underlineStyles = [
             Font::UNDERLINE_NONE,
@@ -825,9 +816,8 @@ class Xml extends BaseReader
 
     /**
      * @param $styleID
-     * @param SimpleXMLElement $styleAttributes
      */
-    private function parseStyleInterior($styleID, SimpleXMLElement $styleAttributes)
+    private function parseStyleInterior($styleID, SimpleXMLElement $styleAttributes): void
     {
         foreach ($styleAttributes as $styleAttributeKey => $styleAttributeValue) {
             switch ($styleAttributeKey) {
@@ -845,9 +835,8 @@ class Xml extends BaseReader
 
     /**
      * @param $styleID
-     * @param SimpleXMLElement $styleAttributes
      */
-    private function parseStyleNumberFormat($styleID, SimpleXMLElement $styleAttributes)
+    private function parseStyleNumberFormat($styleID, SimpleXMLElement $styleAttributes): void
     {
         $fromFormats = ['\-', '\ '];
         $toFormats = ['-', ' '];

src/PhpSpreadsheet/ReferenceHelper.php

@@ -152,7 +152,7 @@ class ReferenceHelper
      * @param int $beforeRow Number of the row we're inserting/deleting before
      * @param int $pNumRows Number of rows to insert/delete (negative values indicate deletion)
      */
-    protected function adjustPageBreaks(Worksheet $pSheet, $pBefore, $beforeColumnIndex, $pNumCols, $beforeRow, $pNumRows)
+    protected function adjustPageBreaks(Worksheet $pSheet, $pBefore, $beforeColumnIndex, $pNumCols, $beforeRow, $pNumRows): void
     {
         $aBreaks = $pSheet->getBreaks();
         ($pNumCols > 0 || $pNumRows > 0) ?
@@ -185,7 +185,7 @@ class ReferenceHelper
      * @param int $beforeRow Number of the row we're inserting/deleting before
      * @param int $pNumRows Number of rows to insert/delete (negative values indicate deletion)
      */
-    protected function adjustComments($pSheet, $pBefore, $beforeColumnIndex, $pNumCols, $beforeRow, $pNumRows)
+    protected function adjustComments($pSheet, $pBefore, $beforeColumnIndex, $pNumCols, $beforeRow, $pNumRows): void
     {
         $aComments = $pSheet->getComments();
         $aNewComments = []; // the new array of all comments
@@ -212,7 +212,7 @@ class ReferenceHelper
      * @param int $beforeRow Number of the row we're inserting/deleting before
      * @param int $pNumRows Number of rows to insert/delete (negative values indicate deletion)
      */
-    protected function adjustHyperlinks($pSheet, $pBefore, $beforeColumnIndex, $pNumCols, $beforeRow, $pNumRows)
+    protected function adjustHyperlinks($pSheet, $pBefore, $beforeColumnIndex, $pNumCols, $beforeRow, $pNumRows): void
     {
         $aHyperlinkCollection = $pSheet->getHyperlinkCollection();
         ($pNumCols > 0 || $pNumRows > 0) ?
@@ -237,7 +237,7 @@ class ReferenceHelper
      * @param int $beforeRow Number of the row we're inserting/deleting before
      * @param int $pNumRows Number of rows to insert/delete (negative values indicate deletion)
      */
-    protected function adjustDataValidations($pSheet, $pBefore, $beforeColumnIndex, $pNumCols, $beforeRow, $pNumRows)
+    protected function adjustDataValidations($pSheet, $pBefore, $beforeColumnIndex, $pNumCols, $beforeRow, $pNumRows): void
     {
         $aDataValidationCollection = $pSheet->getDataValidationCollection();
         ($pNumCols > 0 || $pNumRows > 0) ?
@@ -262,7 +262,7 @@ class ReferenceHelper
      * @param int $beforeRow Number of the row we're inserting/deleting before
      * @param int $pNumRows Number of rows to insert/delete (negative values indicate deletion)
      */
-    protected function adjustMergeCells($pSheet, $pBefore, $beforeColumnIndex, $pNumCols, $beforeRow, $pNumRows)
+    protected function adjustMergeCells($pSheet, $pBefore, $beforeColumnIndex, $pNumCols, $beforeRow, $pNumRows): void
     {
         $aMergeCells = $pSheet->getMergeCells();
         $aNewMergeCells = []; // the new array of all merge cells
@@ -283,7 +283,7 @@ class ReferenceHelper
      * @param int $beforeRow Number of the row we're inserting/deleting before
      * @param int $pNumRows Number of rows to insert/delete (negative values indicate deletion)
      */
-    protected function adjustProtectedCells($pSheet, $pBefore, $beforeColumnIndex, $pNumCols, $beforeRow, $pNumRows)
+    protected function adjustProtectedCells($pSheet, $pBefore, $beforeColumnIndex, $pNumCols, $beforeRow, $pNumRows): void
     {
         $aProtectedCells = $pSheet->getProtectedCells();
         ($pNumCols > 0 || $pNumRows > 0) ?
@@ -307,7 +307,7 @@ class ReferenceHelper
      * @param int $beforeRow Number of the row we're inserting/deleting before
      * @param int $pNumRows Number of rows to insert/delete (negative values indicate deletion)
      */
-    protected function adjustColumnDimensions($pSheet, $pBefore, $beforeColumnIndex, $pNumCols, $beforeRow, $pNumRows)
+    protected function adjustColumnDimensions($pSheet, $pBefore, $beforeColumnIndex, $pNumCols, $beforeRow, $pNumRows): void
     {
         $aColumnDimensions = array_reverse($pSheet->getColumnDimensions(), true);
         if (!empty($aColumnDimensions)) {
@@ -332,7 +332,7 @@ class ReferenceHelper
      * @param int $beforeRow Number of the row we're inserting/deleting before
      * @param int $pNumRows Number of rows to insert/delete (negative values indicate deletion)
      */
-    protected function adjustRowDimensions($pSheet, $pBefore, $beforeColumnIndex, $pNumCols, $beforeRow, $pNumRows)
+    protected function adjustRowDimensions($pSheet, $pBefore, $beforeColumnIndex, $pNumCols, $beforeRow, $pNumRows): void
     {
         $aRowDimensions = array_reverse($pSheet->getRowDimensions(), true);
         if (!empty($aRowDimensions)) {
@@ -364,7 +364,7 @@ class ReferenceHelper
      * @param int $pNumRows Number of rows to insert/delete (negative values indicate deletion)
      * @param Worksheet $pSheet The worksheet that we're editing
      */
-    public function insertNewBefore($pBefore, $pNumCols, $pNumRows, Worksheet $pSheet)
+    public function insertNewBefore($pBefore, $pNumCols, $pNumRows, Worksheet $pSheet): void
     {
         $remove = ($pNumCols < 0 || $pNumRows < 0);
         $allCoordinates = $pSheet->getCoordinates();
@@ -789,7 +789,7 @@ class ReferenceHelper
      * @param string $oldName Old name (name to replace)
      * @param string $newName New name
      */
-    public function updateNamedFormulas(Spreadsheet $spreadsheet, $oldName = '', $newName = '')
+    public function updateNamedFormulas(Spreadsheet $spreadsheet, $oldName = '', $newName = ''): void
     {
         if ($oldName == '') {
             return;

src/PhpSpreadsheet/RichText/RichText.php

@@ -20,7 +20,7 @@ class RichText implements IComparable
      *
      * @param Cell $pCell
      */
-    public function __construct(Cell $pCell = null)
+    public function __construct(?Cell $pCell = null)
     {
         // Initialise variables
         $this->richTextElements = [];

src/PhpSpreadsheet/RichText/Run.php

@@ -42,7 +42,7 @@ class Run extends TextElement implements ITextElement
      *
      * @return $this
      */
-    public function setFont(Font $pFont = null)
+    public function setFont(?Font $pFont = null)
     {
         $this->font = $pFont;
 

src/PhpSpreadsheet/Settings.php

@@ -60,7 +60,7 @@ class Settings
      * @param string $rendererClass Class name of the chart renderer
      *    eg: PhpOffice\PhpSpreadsheet\Chart\Renderer\JpGraph
      */
-    public static function setChartRenderer($rendererClass)
+    public static function setChartRenderer($rendererClass): void
     {
         if (!is_a($rendererClass, IRenderer::class, true)) {
             throw new Exception('Chart renderer must implement ' . IRenderer::class);
@@ -85,7 +85,7 @@ class Settings
      *
      * @param int $options Default options for libxml loader
      */
-    public static function setLibXmlLoaderOptions($options)
+    public static function setLibXmlLoaderOptions($options): void
     {
         if ($options === null && defined('LIBXML_DTDLOAD')) {
             $options = LIBXML_DTDLOAD | LIBXML_DTDATTR;
@@ -120,7 +120,7 @@ class Settings
      *
      * @param bool $state
      */
-    public static function setLibXmlDisableEntityLoader($state)
+    public static function setLibXmlDisableEntityLoader($state): void
     {
         self::$libXmlDisableEntityLoader = (bool) $state;
     }
@@ -137,10 +137,8 @@ class Settings
 
     /**
      * Sets the implementation of cache that should be used for cell collection.
-     *
-     * @param CacheInterface $cache
      */
-    public static function setCache(CacheInterface $cache)
+    public static function setCache(CacheInterface $cache): void
     {
         self::$cache = $cache;
     }

src/PhpSpreadsheet/Shared/Date.php

@@ -4,6 +4,7 @@ namespace PhpOffice\PhpSpreadsheet\Shared;
 
 use DateTimeInterface;
 use DateTimeZone;
+use Exception;
 use PhpOffice\PhpSpreadsheet\Calculation\DateTime;
 use PhpOffice\PhpSpreadsheet\Calculation\Functions;
 use PhpOffice\PhpSpreadsheet\Cell\Cell;
@@ -57,7 +58,7 @@ class Date
     /**
      * Default timezone to use for DateTime objects.
      *
-     * @var null|\DateTimeZone
+     * @var null|DateTimeZone
      */
     protected static $defaultTimeZone;
 
@@ -139,7 +140,7 @@ class Date
             return new DateTimeZone($timeZone);
         }
 
-        throw new \Exception('Invalid timezone');
+        throw new Exception('Invalid timezone');
     }
 
     /**
@@ -311,8 +312,6 @@ class Date
     /**
      * Is a given cell a date/time?
      *
-     * @param Cell $pCell
-     *
      * @return bool
      */
     public static function isDateTime(Cell $pCell)
@@ -328,8 +327,6 @@ class Date
     /**
      * Is a given number format a date/time?
      *
-     * @param NumberFormat $pFormat
-     *
      * @return bool
      */
     public static function isDateTimeFormat(NumberFormat $pFormat)

src/PhpSpreadsheet/Shared/Escher/DgContainer.php

@@ -25,7 +25,7 @@ class DgContainer
         return $this->dgId;
     }
 
-    public function setDgId($value)
+    public function setDgId($value): void
     {
         $this->dgId = $value;
     }
@@ -35,7 +35,7 @@ class DgContainer
         return $this->lastSpId;
     }
 
-    public function setLastSpId($value)
+    public function setLastSpId($value): void
     {
         $this->lastSpId = $value;
     }

src/PhpSpreadsheet/Shared/Escher/DgContainer/SpgrContainer.php

@@ -23,7 +23,7 @@ class SpgrContainer
      *
      * @param \PhpOffice\PhpSpreadsheet\Shared\Escher\DgContainer\SpgrContainer $parent
      */
-    public function setParent($parent)
+    public function setParent($parent): void
     {
         $this->parent = $parent;
     }
@@ -43,7 +43,7 @@ class SpgrContainer
      *
      * @param mixed $child
      */
-    public function addChild($child)
+    public function addChild($child): void
     {
         $this->children[] = $child;
         $child->setParent($this);

src/PhpSpreadsheet/Shared/Escher/DgContainer/SpgrContainer/SpContainer.php

@@ -95,7 +95,7 @@ class SpContainer
      *
      * @param SpgrContainer $parent
      */
-    public function setParent($parent)
+    public function setParent($parent): void
     {
         $this->parent = $parent;
     }
@@ -115,7 +115,7 @@ class SpContainer
      *
      * @param bool $value
      */
-    public function setSpgr($value)
+    public function setSpgr($value): void
     {
         $this->spgr = $value;
     }
@@ -135,7 +135,7 @@ class SpContainer
      *
      * @param int $value
      */
-    public function setSpType($value)
+    public function setSpType($value): void
     {
         $this->spType = $value;
     }
@@ -155,7 +155,7 @@ class SpContainer
      *
      * @param int $value
      */
-    public function setSpFlag($value)
+    public function setSpFlag($value): void
     {
         $this->spFlag = $value;
     }
@@ -175,7 +175,7 @@ class SpContainer
      *
      * @param int $value
      */
-    public function setSpId($value)
+    public function setSpId($value): void
     {
         $this->spId = $value;
     }
@@ -196,7 +196,7 @@ class SpContainer
      * @param int $property The number specifies the option
      * @param mixed $value
      */
-    public function setOPT($property, $value)
+    public function setOPT($property, $value): void
     {
         $this->OPT[$property] = $value;
     }
@@ -232,7 +232,7 @@ class SpContainer
      *
      * @param string $value eg: 'A1'
      */
-    public function setStartCoordinates($value)
+    public function setStartCoordinates($value): void
     {
         $this->startCoordinates = $value;
     }
@@ -252,7 +252,7 @@ class SpContainer
      *
      * @param int $startOffsetX
      */
-    public function setStartOffsetX($startOffsetX)
+    public function setStartOffsetX($startOffsetX): void
     {
         $this->startOffsetX = $startOffsetX;
     }
@@ -272,7 +272,7 @@ class SpContainer
      *
      * @param int $startOffsetY
      */
-    public function setStartOffsetY($startOffsetY)
+    public function setStartOffsetY($startOffsetY): void
     {
         $this->startOffsetY = $startOffsetY;
     }
@@ -292,7 +292,7 @@ class SpContainer
      *
      * @param string $value eg: 'A1'
      */
-    public function setEndCoordinates($value)
+    public function setEndCoordinates($value): void
     {
         $this->endCoordinates = $value;
     }
@@ -312,7 +312,7 @@ class SpContainer
      *
      * @param int $endOffsetX
      */
-    public function setEndOffsetX($endOffsetX)
+    public function setEndOffsetX($endOffsetX): void
     {
         $this->endOffsetX = $endOffsetX;
     }
@@ -332,7 +332,7 @@ class SpContainer
      *
      * @param int $endOffsetY
      */
-    public function setEndOffsetY($endOffsetY)
+    public function setEndOffsetY($endOffsetY): void
     {
         $this->endOffsetY = $endOffsetY;
     }

src/PhpSpreadsheet/Shared/Escher/DggContainer.php

@@ -61,7 +61,7 @@ class DggContainer
      *
      * @param int $value
      */
-    public function setSpIdMax($value)
+    public function setSpIdMax($value): void
     {
         $this->spIdMax = $value;
     }
@@ -81,7 +81,7 @@ class DggContainer
      *
      * @param int $value
      */
-    public function setCDgSaved($value)
+    public function setCDgSaved($value): void
     {
         $this->cDgSaved = $value;
     }
@@ -101,7 +101,7 @@ class DggContainer
      *
      * @param int $value
      */
-    public function setCSpSaved($value)
+    public function setCSpSaved($value): void
     {
         $this->cSpSaved = $value;
     }
@@ -121,7 +121,7 @@ class DggContainer
      *
      * @param DggContainer\BstoreContainer $bstoreContainer
      */
-    public function setBstoreContainer($bstoreContainer)
+    public function setBstoreContainer($bstoreContainer): void
     {
         $this->bstoreContainer = $bstoreContainer;
     }
@@ -132,7 +132,7 @@ class DggContainer
      * @param int $property The number specifies the option
      * @param mixed $value
      */
-    public function setOPT($property, $value)
+    public function setOPT($property, $value): void
     {
         $this->OPT[$property] = $value;
     }
@@ -168,7 +168,7 @@ class DggContainer
      *
      * @param array $pValue
      */
-    public function setIDCLs($pValue)
+    public function setIDCLs($pValue): void
     {
         $this->IDCLs = $pValue;
     }

src/PhpSpreadsheet/Shared/Escher/DggContainer/BstoreContainer.php

@@ -16,7 +16,7 @@ class BstoreContainer
      *
      * @param BstoreContainer\BSE $BSE
      */
-    public function addBSE($BSE)
+    public function addBSE($BSE): void
     {
         $this->BSECollection[] = $BSE;
         $BSE->setParent($this);

src/PhpSpreadsheet/Shared/Escher/DggContainer/BstoreContainer/BSE.php

@@ -41,7 +41,7 @@ class BSE
      *
      * @param \PhpOffice\PhpSpreadsheet\Shared\Escher\DggContainer\BstoreContainer $parent
      */
-    public function setParent($parent)
+    public function setParent($parent): void
     {
         $this->parent = $parent;
     }
@@ -61,7 +61,7 @@ class BSE
      *
      * @param BSE\Blip $blip
      */
-    public function setBlip($blip)
+    public function setBlip($blip): void
     {
         $this->blip = $blip;
         $blip->setParent($this);
@@ -82,7 +82,7 @@ class BSE
      *
      * @param int $blipType
      */
-    public function setBlipType($blipType)
+    public function setBlipType($blipType): void
     {
         $this->blipType = $blipType;
     }

src/PhpSpreadsheet/Shared/Escher/DggContainer/BstoreContainer/BSE/Blip.php

@@ -33,7 +33,7 @@ class Blip
      *
      * @param string $data
      */
-    public function setData($data)
+    public function setData($data): void
     {
         $this->data = $data;
     }
@@ -43,7 +43,7 @@ class Blip
      *
      * @param \PhpOffice\PhpSpreadsheet\Shared\Escher\DggContainer\BstoreContainer\BSE $parent
      */
-    public function setParent($parent)
+    public function setParent($parent): void
     {
         $this->parent = $parent;
     }

src/PhpSpreadsheet/Shared/File.php

@@ -19,7 +19,7 @@ class File
      *
      * @param bool $useUploadTempDir Use File Upload Temporary directory (true or false)
      */
-    public static function setUseUploadTempDirectory($useUploadTempDir)
+    public static function setUseUploadTempDirectory($useUploadTempDir): void
     {
         self::$useUploadTempDirectory = (bool) $useUploadTempDir;
     }
@@ -129,7 +129,7 @@ class File
      *
      * @param string $filename
      */
-    public static function assertFile($filename)
+    public static function assertFile($filename): void
     {
         if (!is_file($filename)) {
             throw new InvalidArgumentException('File "' . $filename . '" does not exist.');

src/PhpSpreadsheet/Shared/Font.php

@@ -198,7 +198,7 @@ class Font
      *
      * @param string $pValue
      */
-    public static function setTrueTypeFontPath($pValue)
+    public static function setTrueTypeFontPath($pValue): void
     {
         self::$trueTypeFontPath = $pValue;
     }
@@ -223,7 +223,7 @@ class Font
      *
      * @return int Column width
      */
-    public static function calculateColumnWidth(\PhpOffice\PhpSpreadsheet\Style\Font $font, $cellText = '', $rotation = 0, \PhpOffice\PhpSpreadsheet\Style\Font $defaultFont = null)
+    public static function calculateColumnWidth(\PhpOffice\PhpSpreadsheet\Style\Font $font, $cellText = '', $rotation = 0, ?\PhpOffice\PhpSpreadsheet\Style\Font $defaultFont = null)
     {
         // If it is rich text, use plain text
         if ($cellText instanceof RichText) {
@@ -303,7 +303,6 @@ class Font
      * Get approximate width in pixels for a string of text in a certain font at a certain rotation angle.
      *
      * @param string $columnText
-     * @param \PhpOffice\PhpSpreadsheet\Style\Font $font
      * @param int $rotation
      *
      * @return int Text width in pixels (no padding added)

src/PhpSpreadsheet/Shared/JAMA/EigenvalueDecomposition.php

@@ -73,7 +73,7 @@ class EigenvalueDecomposition
     /**
      * Symmetric Householder reduction to tridiagonal form.
      */
-    private function tred2()
+    private function tred2(): void
     {
         //  This is derived from the Algol procedures tred2 by
         //  Bowdler, Martin, Reinsch, and Wilkinson, Handbook for
@@ -96,7 +96,7 @@ class EigenvalueDecomposition
                 // Generate Householder vector.
                 for ($k = 0; $k < $i; ++$k) {
                     $this->d[$k] /= $scale;
-                    $h += pow($this->d[$k], 2);
+                    $h += $this->d[$k] ** 2;
                 }
                 $f = $this->d[$i_];
                 $g = sqrt($h);
@@ -180,7 +180,7 @@ class EigenvalueDecomposition
      *    Auto. Comp., Vol.ii-Linear Algebra, and the corresponding
      * Fortran subroutine in EISPACK.
      */
-    private function tql2()
+    private function tql2(): void
     {
         for ($i = 1; $i < $this->n; ++$i) {
             $this->e[$i - 1] = $this->e[$i];
@@ -188,7 +188,7 @@ class EigenvalueDecomposition
         $this->e[$this->n - 1] = 0.0;
         $f = 0.0;
         $tst1 = 0.0;
-        $eps = pow(2.0, -52.0);
+        $eps = 2.0 ** (-52.0);
 
         for ($l = 0; $l < $this->n; ++$l) {
             // Find small subdiagonal element
@@ -206,7 +206,7 @@ class EigenvalueDecomposition
                 $iter = 0;
                 do {
                     // Could check iteration count here.
-                    $iter += 1;
+                    ++$iter;
                     // Compute implicit shift
                     $g = $this->d[$l];
                     $p = ($this->d[$l + 1] - $g) / (2.0 * $this->e[$l]);
@@ -287,7 +287,7 @@ class EigenvalueDecomposition
      *    Vol.ii-Linear Algebra, and the corresponding
      * Fortran subroutines in EISPACK.
      */
-    private function orthes()
+    private function orthes(): void
     {
         $low = 0;
         $high = $this->n - 1;
@@ -372,7 +372,7 @@ class EigenvalueDecomposition
      * @param mixed $yr
      * @param mixed $yi
      */
-    private function cdiv($xr, $xi, $yr, $yi)
+    private function cdiv($xr, $xi, $yr, $yi): void
     {
         if (abs($yr) > abs($yi)) {
             $r = $yi / $yr;
@@ -395,21 +395,21 @@ class EigenvalueDecomposition
      *    Vol.ii-Linear Algebra, and the corresponding
      * Fortran subroutine in EISPACK.
      */
-    private function hqr2()
+    private function hqr2(): void
     {
         //  Initialize
         $nn = $this->n;
         $n = $nn - 1;
         $low = 0;
         $high = $nn - 1;
-        $eps = pow(2.0, -52.0);
+        $eps = 2.0 ** (-52.0);
         $exshift = 0.0;
         $p = $q = $r = $s = $z = 0;
         // Store roots isolated by balanc and compute matrix norm
         $norm = 0.0;
 
         for ($i = 0; $i < $nn; ++$i) {
-            if (($i < $low) or ($i > $high)) {
+            if (($i < $low) || ($i > $high)) {
                 $this->d[$i] = $this->H[$i][$i];
                 $this->e[$i] = 0.0;
             }

src/PhpSpreadsheet/Shared/JAMA/Matrix.php

@@ -159,11 +159,6 @@ class Matrix
      *
      *    Get a submatrix
      *
-     * @param int $i0 Initial row index
-     * @param int $iF Final row index
-     * @param int $j0 Initial column index
-     * @param int $jF Final column index
-     *
      * @return Matrix Submatrix
      */
     public function getMatrix(...$args)
@@ -477,8 +472,6 @@ class Matrix
      *
      *    A + B
      *
-     * @param mixed $B Matrix/Array
-     *
      * @return Matrix Sum
      */
     public function plus(...$args)
@@ -522,8 +515,6 @@ class Matrix
      *
      *    A = A + B
      *
-     * @param mixed $B Matrix/Array
-     *
      * @return $this
      */
     public function plusEquals(...$args)
@@ -581,8 +572,6 @@ class Matrix
      *
      *    A - B
      *
-     * @param mixed $B Matrix/Array
-     *
      * @return Matrix Sum
      */
     public function minus(...$args)
@@ -626,8 +615,6 @@ class Matrix
      *
      *    A = A - B
      *
-     * @param mixed $B Matrix/Array
-     *
      * @return $this
      */
     public function minusEquals(...$args)
@@ -686,8 +673,6 @@ class Matrix
      *    Element-by-element multiplication
      *    Cij = Aij * Bij
      *
-     * @param mixed $B Matrix/Array
-     *
      * @return Matrix Matrix Cij
      */
     public function arrayTimes(...$args)
@@ -732,8 +717,6 @@ class Matrix
      *    Element-by-element multiplication
      *    Aij = Aij * Bij
      *
-     * @param mixed $B Matrix/Array
-     *
      * @return $this
      */
     public function arrayTimesEquals(...$args)
@@ -792,8 +775,6 @@ class Matrix
      *    Element-by-element right division
      *    A / B
      *
-     * @param Matrix $B Matrix B
-     *
      * @return Matrix Division result
      */
     public function arrayRightDivide(...$args)
@@ -857,8 +838,6 @@ class Matrix
      *    Element-by-element right division
      *    Aij = Aij / Bij
      *
-     * @param mixed $B Matrix/Array
-     *
      * @return Matrix Matrix Aij
      */
     public function arrayRightDivideEquals(...$args)
@@ -903,8 +882,6 @@ class Matrix
      *    Element-by-element Left division
      *    A / B
      *
-     * @param Matrix $B Matrix B
-     *
      * @return Matrix Division result
      */
     public function arrayLeftDivide(...$args)
@@ -949,8 +926,6 @@ class Matrix
      *    Element-by-element Left division
      *    Aij = Aij / Bij
      *
-     * @param mixed $B Matrix/Array
-     *
      * @return Matrix Matrix Aij
      */
     public function arrayLeftDivideEquals(...$args)
@@ -994,8 +969,6 @@ class Matrix
      *
      *    Matrix multiplication
      *
-     * @param mixed $n Matrix/Array/Scalar
-     *
      * @return Matrix Product
      */
     public function times(...$args)
@@ -1089,8 +1062,6 @@ class Matrix
      *
      *    A = A ^ B
      *
-     * @param mixed $B Matrix/Array
-     *
      * @return $this
      */
     public function power(...$args)
@@ -1130,7 +1101,7 @@ class Matrix
                         $validValues &= StringHelper::convertToNumberIfFraction($value);
                     }
                     if ($validValues) {
-                        $this->A[$i][$j] = pow($this->A[$i][$j], $value);
+                        $this->A[$i][$j] = $this->A[$i][$j] ** $value;
                     } else {
                         $this->A[$i][$j] = Functions::NAN();
                     }
@@ -1148,8 +1119,6 @@ class Matrix
      *
      *    A = A & B
      *
-     * @param mixed $B Matrix/Array
-     *
      * @return $this
      */
     public function concat(...$args)

src/PhpSpreadsheet/Shared/JAMA/SingularValueDecomposition.php

@@ -117,7 +117,7 @@ class SingularValueDecomposition
                 }
             }
 
-            if ($wantu and ($k < $nct)) {
+            if ($wantu && ($k < $nct)) {
                 // Place the transformation in U for subsequent back
                 // multiplication.
                 for ($i = $k; $i < $this->m; ++$i) {
@@ -143,7 +143,7 @@ class SingularValueDecomposition
                     $e[$k + 1] += 1.0;
                 }
                 $e[$k] = -$e[$k];
-                if (($k + 1 < $this->m) and ($e[$k] != 0.0)) {
+                if (($k + 1 < $this->m) && ($e[$k] != 0.0)) {
                     // Apply the transformation.
                     for ($i = $k + 1; $i < $this->m; ++$i) {
                         $work[$i] = 0.0;
@@ -221,7 +221,7 @@ class SingularValueDecomposition
         // If required, generate V.
         if ($wantv) {
             for ($k = $this->n - 1; $k >= 0; --$k) {
-                if (($k < $nrt) and ($e[$k] != 0.0)) {
+                if (($k < $nrt) && ($e[$k] != 0.0)) {
                     for ($j = $k + 1; $j < $nu; ++$j) {
                         $t = 0;
                         for ($i = $k + 1; $i < $this->n; ++$i) {
@@ -243,7 +243,7 @@ class SingularValueDecomposition
         // Main iteration loop for the singular values.
         $pp = $p - 1;
         $iter = 0;
-        $eps = pow(2.0, -52.0);
+        $eps = 2.0 ** (-52.0);
 
         while ($p > 0) {
             // Here is where a test for too many iterations would go.
@@ -415,14 +415,14 @@ class SingularValueDecomposition
                         $t = $this->s[$k];
                         $this->s[$k] = $this->s[$k + 1];
                         $this->s[$k + 1] = $t;
-                        if ($wantv and ($k < $this->n - 1)) {
+                        if ($wantv && ($k < $this->n - 1)) {
                             for ($i = 0; $i < $this->n; ++$i) {
                                 $t = $this->V[$i][$k + 1];
                                 $this->V[$i][$k + 1] = $this->V[$i][$k];
                                 $this->V[$i][$k] = $t;
                             }
                         }
-                        if ($wantu and ($k < $this->m - 1)) {
+                        if ($wantu && ($k < $this->m - 1)) {
                             for ($i = 0; $i < $this->m; ++$i) {
                                 $t = $this->U[$i][$k + 1];
                                 $this->U[$i][$k + 1] = $this->U[$i][$k];
@@ -513,7 +513,7 @@ class SingularValueDecomposition
      */
     public function rank()
     {
-        $eps = pow(2.0, -52.0);
+        $eps = 2.0 ** (-52.0);
         $tol = max($this->m, $this->n) * $this->s[0] * $eps;
         $r = 0;
         $iMax = count($this->s);

src/PhpSpreadsheet/Shared/OLE.php

@@ -117,7 +117,7 @@ class OLE
      */
     public function read($file)
     {
-        $fh = fopen($file, 'r');
+        $fh = fopen($file, 'rb');
         if (!$fh) {
             throw new ReaderException("Can't open file $file");
         }
@@ -133,8 +133,8 @@ class OLE
             throw new ReaderException('Only Little-Endian encoding is supported.');
         }
         // Size of blocks and short blocks in bytes
-        $this->bigBlockSize = pow(2, self::_readInt2($fh));
+        $this->bigBlockSize = 2 ** self::_readInt2($fh);
-        $this->smallBlockSize = pow(2, self::_readInt2($fh));
+        $this->smallBlockSize = 2 ** self::_readInt2($fh);
 
         // Skip UID, revision number and version number
         fseek($fh, 44);
@@ -239,7 +239,7 @@ class OLE
             $path .= '&blockId=' . $blockIdOrPps;
         }
 
-        return fopen($path, 'r');
+        return fopen($path, 'rb');
     }
 
     /**
@@ -502,7 +502,7 @@ class OLE
         }
 
         // factor used for separating numbers into 4 bytes parts
-        $factor = pow(2, 32);
+        $factor = 2 ** 32;
 
         // days from 1-1-1601 until the beggining of UNIX era
         $days = 134774;

src/PhpSpreadsheet/Shared/OLE/ChainedBlockStream.php

@@ -101,7 +101,7 @@ class ChainedBlockStream
     /**
      * Implements support for fclose().
      */
-    public function stream_close() // @codingStandardsIgnoreLine
+    public function stream_close(): void // @codingStandardsIgnoreLine
     {
         $this->ole = null;
         unset($GLOBALS['_OLE_INSTANCES']);

src/PhpSpreadsheet/Shared/OLE/PPS/File.php

@@ -59,7 +59,7 @@ class File extends PPS
      *
      * @param string $data The data to append
      */
-    public function append($data)
+    public function append($data): void
     {
         $this->_data .= $data;
     }

src/PhpSpreadsheet/Shared/OLE/PPS/Root.php

@@ -73,12 +73,10 @@ class Root extends PPS
         $this->fileHandle = $fileHandle;
 
         // Initial Setting for saving
-        $this->bigBlockSize = pow(
+        $this->bigBlockSize = 2 ** (
-            2,
             (isset($this->bigBlockSize)) ? self::adjust2($this->bigBlockSize) : 9
             );
-        $this->smallBlockSize = pow(
+        $this->smallBlockSize = 2 ** (
-            2,
             (isset($this->smallBlockSize)) ? self::adjust2($this->smallBlockSize) : 6
             );
 
@@ -146,9 +144,9 @@ class Root extends PPS
      *
      * @param int $i2 The argument
      *
-     * @see save()
-     *
      * @return float
+     *
+     * @see save()
      */
     private static function adjust2($i2)
     {
@@ -164,7 +162,7 @@ class Root extends PPS
      * @param int $iBBcnt
      * @param int $iPPScnt
      */
-    public function _saveHeader($iSBDcnt, $iBBcnt, $iPPScnt)
+    public function _saveHeader($iSBDcnt, $iBBcnt, $iPPScnt): void
     {
         $FILE = $this->fileHandle;
 
@@ -243,7 +241,7 @@ class Root extends PPS
      * @param int $iStBlk
      * @param array &$raList Reference to array of PPS's
      */
-    public function _saveBigData($iStBlk, &$raList)
+    public function _saveBigData($iStBlk, &$raList): void
     {
         $FILE = $this->fileHandle;
 
@@ -325,7 +323,7 @@ class Root extends PPS
      *
      * @param array $raList Reference to an array with all PPS's
      */
-    public function _savePps(&$raList)
+    public function _savePps(&$raList): void
     {
         // Save each PPS WK
         $iC = count($raList);
@@ -347,7 +345,7 @@ class Root extends PPS
      * @param int $iBsize
      * @param int $iPpsCnt
      */
-    public function _saveBbd($iSbdSize, $iBsize, $iPpsCnt)
+    public function _saveBbd($iSbdSize, $iBsize, $iPpsCnt): void
     {
         $FILE = $this->fileHandle;
         // Calculate Basic Setting

src/PhpSpreadsheet/Shared/OLERead.php

@@ -95,7 +95,7 @@ class OLERead
      *
      * @param $pFilename string Filename
      */
-    public function read($pFilename)
+    public function read($pFilename): void
     {
         File::assertFile($pFilename);
 
@@ -258,7 +258,7 @@ class OLERead
     /**
      * Read entries in the directory stream.
      */
-    private function readPropertySets()
+    private function readPropertySets(): void
     {
         $offset = 0;
 

src/PhpSpreadsheet/Shared/StringHelper.php

@@ -63,7 +63,7 @@ class StringHelper
     /**
      * Build control characters array.
      */
-    private static function buildControlCharacters()
+    private static function buildControlCharacters(): void
     {
         for ($i = 0; $i <= 31; ++$i) {
             if ($i != 9 && $i != 10 && $i != 13) {
@@ -77,7 +77,7 @@ class StringHelper
     /**
      * Build SYLK characters array.
      */
-    private static function buildSYLKCharacters()
+    private static function buildSYLKCharacters(): void
     {
         self::$SYLKCharacters = [
             "\x1B 0" => chr(0),
@@ -272,7 +272,7 @@ class StringHelper
         return self::$isIconvEnabled;
     }
 
-    private static function buildCharacterSets()
+    private static function buildCharacterSets(): void
     {
         if (empty(self::$controlCharacters)) {
             self::buildControlCharacters();
@@ -603,7 +603,7 @@ class StringHelper
      *
      * @param string $pValue Character for decimal separator
      */
-    public static function setDecimalSeparator($pValue)
+    public static function setDecimalSeparator($pValue): void
     {
         self::$decimalSeparator = $pValue;
     }
@@ -636,7 +636,7 @@ class StringHelper
      *
      * @param string $pValue Character for thousands separator
      */
-    public static function setThousandsSeparator($pValue)
+    public static function setThousandsSeparator($pValue): void
     {
         self::$thousandsSeparator = $pValue;
     }
@@ -674,7 +674,7 @@ class StringHelper
      *
      * @param string $pValue Character for currency code
      */
-    public static function setCurrencyCode($pValue)
+    public static function setCurrencyCode($pValue): void
     {
         self::$currencyCode = $pValue;
     }

src/PhpSpreadsheet/Shared/Trend/BestFit.php

@@ -341,7 +341,7 @@ class BestFit
         return $this->yBestFitValues;
     }
 
-    protected function calculateGoodnessOfFit($sumX, $sumY, $sumX2, $sumY2, $sumXY, $meanX, $meanY, $const)
+    protected function calculateGoodnessOfFit($sumX, $sumY, $sumX2, $sumY2, $sumXY, $meanX, $meanY, $const): void
     {
         $SSres = $SScov = $SScor = $SStot = $SSsex = 0.0;
         foreach ($this->xValues as $xKey => $xValue) {
@@ -377,7 +377,7 @@ class BestFit
 
         $this->SSRegression = $this->goodnessOfFit * $SStot;
         $this->covariance = $SScov / $this->valueCount;
-        $this->correlation = ($this->valueCount * $sumXY - $sumX * $sumY) / sqrt(($this->valueCount * $sumX2 - pow($sumX, 2)) * ($this->valueCount * $sumY2 - pow($sumY, 2)));
+        $this->correlation = ($this->valueCount * $sumXY - $sumX * $sumY) / sqrt(($this->valueCount * $sumX2 - $sumX ** 2) * ($this->valueCount * $sumY2 - $sumY ** 2));
         $this->slopeSE = $this->stdevOfResiduals / sqrt($SSsex);
         $this->intersectSE = $this->stdevOfResiduals * sqrt(1 / ($this->valueCount - ($sumX * $sumX) / $sumX2));
         if ($this->SSResiduals != 0.0) {
@@ -400,7 +400,7 @@ class BestFit
      * @param float[] $xValues
      * @param bool $const
      */
-    protected function leastSquareFit(array $yValues, array $xValues, $const)
+    protected function leastSquareFit(array $yValues, array $xValues, $const): void
     {
         // calculate sums
         $x_sum = array_sum($xValues);

src/PhpSpreadsheet/Shared/Trend/ExponentialBestFit.php

@@ -21,7 +21,7 @@ class ExponentialBestFit extends BestFit
      */
     public function getValueOfYForX($xValue)
     {
-        return $this->getIntersect() * pow($this->getSlope(), ($xValue - $this->xOffset));
+        return $this->getIntersect() * $this->getSlope() ** ($xValue - $this->xOffset);
     }
 
     /**
@@ -90,7 +90,7 @@ class ExponentialBestFit extends BestFit
      * @param float[] $xValues The set of X-values for this regression
      * @param bool $const
      */
-    private function exponentialRegression($yValues, $xValues, $const)
+    private function exponentialRegression($yValues, $xValues, $const): void
     {
         foreach ($yValues as &$value) {
             if ($value < 0.0) {

src/PhpSpreadsheet/Shared/Trend/LinearBestFit.php

@@ -58,7 +58,7 @@ class LinearBestFit extends BestFit
      * @param float[] $xValues The set of X-values for this regression
      * @param bool $const
      */
-    private function linearRegression($yValues, $xValues, $const)
+    private function linearRegression($yValues, $xValues, $const): void
     {
         $this->leastSquareFit($yValues, $xValues, $const);
     }

src/PhpSpreadsheet/Shared/Trend/LogarithmicBestFit.php

@@ -58,7 +58,7 @@ class LogarithmicBestFit extends BestFit
      * @param float[] $xValues The set of X-values for this regression
      * @param bool $const
      */
-    private function logarithmicRegression($yValues, $xValues, $const)
+    private function logarithmicRegression($yValues, $xValues, $const): void
     {
         foreach ($xValues as &$value) {
             if ($value < 0.0) {

src/PhpSpreadsheet/Shared/Trend/PolynomialBestFit.php

@@ -44,7 +44,7 @@ class PolynomialBestFit extends BestFit
         $slope = $this->getSlope();
         foreach ($slope as $key => $value) {
             if ($value != 0.0) {
-                $retVal += $value * pow($xValue, $key + 1);
+                $retVal += $value * $xValue ** ($key + 1);
             }
         }
 
@@ -121,7 +121,7 @@ class PolynomialBestFit extends BestFit
      * @param float[] $yValues The set of Y-values for this regression
      * @param float[] $xValues The set of X-values for this regression
      */
-    private function polynomialRegression($order, $yValues, $xValues)
+    private function polynomialRegression($order, $yValues, $xValues): void
     {
         // calculate sums
         $x_sum = array_sum($xValues);
@@ -144,7 +144,7 @@ class PolynomialBestFit extends BestFit
         $B = [];
         for ($i = 0; $i < $this->valueCount; ++$i) {
             for ($j = 0; $j <= $order; ++$j) {
-                $A[$i][$j] = pow($xValues[$i], $j);
+                $A[$i][$j] = $xValues[$i] ** $j;
             }
         }
         for ($i = 0; $i < $this->valueCount; ++$i) {
@@ -157,7 +157,7 @@ class PolynomialBestFit extends BestFit
         $coefficients = [];
         for ($i = 0; $i < $C->getRowDimension(); ++$i) {
             $r = $C->get($i, 0);
-            if (abs($r) <= pow(10, -9)) {
+            if (abs($r) <= 10 ** (-9)) {
                 $r = 0;
             }
             $coefficients[] = $r;

src/PhpSpreadsheet/Shared/Trend/PowerBestFit.php

@@ -21,7 +21,7 @@ class PowerBestFit extends BestFit
      */
     public function getValueOfYForX($xValue)
     {
-        return $this->getIntersect() * pow(($xValue - $this->xOffset), $this->getSlope());
+        return $this->getIntersect() * ($xValue - $this->xOffset) ** $this->getSlope();
     }
 
     /**
@@ -33,7 +33,7 @@ class PowerBestFit extends BestFit
      */
     public function getValueOfXForY($yValue)
     {
-        return pow((($yValue + $this->yOffset) / $this->getIntersect()), (1 / $this->getSlope()));
+        return (($yValue + $this->yOffset) / $this->getIntersect()) ** (1 / $this->getSlope());
     }
 
     /**
@@ -74,7 +74,7 @@ class PowerBestFit extends BestFit
      * @param float[] $xValues The set of X-values for this regression
      * @param bool $const
      */
-    private function powerRegression($yValues, $xValues, $const)
+    private function powerRegression($yValues, $xValues, $const): void
     {
         foreach ($xValues as &$value) {
             if ($value < 0.0) {

src/PhpSpreadsheet/Shared/Xls.php

@@ -25,7 +25,7 @@ class Xls
         $columnDimensions = $sheet->getColumnDimensions();
 
         // first find the true column width in pixels (uncollapsed and unhidden)
-        if (isset($columnDimensions[$col]) and $columnDimensions[$col]->getWidth() != -1) {
+        if (isset($columnDimensions[$col]) && $columnDimensions[$col]->getWidth() != -1) {
             // then we have column dimension with explicit width
             $columnDimension = $columnDimensions[$col];
             $width = $columnDimension->getWidth();
@@ -41,7 +41,7 @@ class Xls
         }
 
         // now find the effective column width in pixels
-        if (isset($columnDimensions[$col]) and !$columnDimensions[$col]->getVisible()) {
+        if (isset($columnDimensions[$col]) && !$columnDimensions[$col]->getVisible()) {
             $effectivePixelWidth = 0;
         } else {
             $effectivePixelWidth = $pixelWidth;
@@ -68,7 +68,7 @@ class Xls
         $rowDimensions = $sheet->getRowDimensions();
 
         // first find the true row height in pixels (uncollapsed and unhidden)
-        if (isset($rowDimensions[$row]) and $rowDimensions[$row]->getRowHeight() != -1) {
+        if (isset($rowDimensions[$row]) && $rowDimensions[$row]->getRowHeight() != -1) {
             // then we have a row dimension
             $rowDimension = $rowDimensions[$row];
             $rowHeight = $rowDimension->getRowHeight();
@@ -85,7 +85,7 @@ class Xls
         }
 
         // now find the effective row height in pixels
-        if (isset($rowDimensions[$row]) and !$rowDimensions[$row]->getVisible()) {
+        if (isset($rowDimensions[$row]) && !$rowDimensions[$row]->getVisible()) {
             $effectivePixelRowHeight = 0;
         } else {
             $effectivePixelRowHeight = $pixelRowHeight;
@@ -98,7 +98,6 @@ class Xls
      * Get the horizontal distance in pixels between two anchors
      * The distanceX is found as sum of all the spanning columns widths minus correction for the two offsets.
      *
-     * @param Worksheet $sheet
      * @param string $startColumn
      * @param int $startOffsetX Offset within start cell measured in 1/1024 of the cell width
      * @param string $endColumn
@@ -130,7 +129,6 @@ class Xls
      * Get the vertical distance in pixels between two anchors
      * The distanceY is found as sum of all the spanning rows minus two offsets.
      *
-     * @param Worksheet $sheet
      * @param int $startRow (1-based)
      * @param int $startOffsetY Offset within start cell measured in 1/256 of the cell height
      * @param int $endRow (1-based)

src/PhpSpreadsheet/Spreadsheet.php

@@ -210,7 +210,7 @@ class Spreadsheet
      *
      * @param bool $hasMacros true|false
      */
-    public function setHasMacros($hasMacros)
+    public function setHasMacros($hasMacros): void
     {
         $this->hasMacros = (bool) $hasMacros;
     }
@@ -220,7 +220,7 @@ class Spreadsheet
      *
      * @param string $macroCode string|null
      */
-    public function setMacrosCode($macroCode)
+    public function setMacrosCode($macroCode): void
     {
         $this->macrosCode = $macroCode;
         $this->setHasMacros($macroCode !== null);
@@ -241,7 +241,7 @@ class Spreadsheet
      *
      * @param null|string $certificate
      */
-    public function setMacrosCertificate($certificate)
+    public function setMacrosCertificate($certificate): void
     {
         $this->macrosCertificate = $certificate;
     }
@@ -269,7 +269,7 @@ class Spreadsheet
     /**
      * Remove all macros, certificate from spreadsheet.
      */
-    public function discardMacros()
+    public function discardMacros(): void
     {
         $this->hasMacros = false;
         $this->macrosCode = null;
@@ -282,7 +282,7 @@ class Spreadsheet
      * @param null|mixed $target
      * @param null|mixed $xmlData
      */
-    public function setRibbonXMLData($target, $xmlData)
+    public function setRibbonXMLData($target, $xmlData): void
     {
         if ($target !== null && $xmlData !== null) {
             $this->ribbonXMLData = ['target' => $target, 'data' => $xmlData];
@@ -327,7 +327,7 @@ class Spreadsheet
      * @param null|mixed $BinObjectsNames
      * @param null|mixed $BinObjectsData
      */
-    public function setRibbonBinObjects($BinObjectsNames, $BinObjectsData)
+    public function setRibbonBinObjects($BinObjectsNames, $BinObjectsData): void
     {
         if ($BinObjectsNames !== null && $BinObjectsData !== null) {
             $this->ribbonBinObjects = ['names' => $BinObjectsNames, 'data' => $BinObjectsData];
@@ -354,10 +354,8 @@ class Spreadsheet
      * It has to be minimized when the library start to support currently unparsed data.
      *
      * @internal
-     *
-     * @param array $unparsedLoadedData
      */
-    public function setUnparsedLoadedData(array $unparsedLoadedData)
+    public function setUnparsedLoadedData(array $unparsedLoadedData): void
     {
         $this->unparsedLoadedData = $unparsedLoadedData;
     }
@@ -507,7 +505,7 @@ class Spreadsheet
      * Disconnect all worksheets from this PhpSpreadsheet workbook object,
      * typically so that the PhpSpreadsheet object can be unset.
      */
-    public function disconnectWorksheets()
+    public function disconnectWorksheets(): void
     {
         $worksheet = null;
         foreach ($this->workSheetCollection as $k => &$worksheet) {
@@ -540,10 +538,8 @@ class Spreadsheet
 
     /**
      * Set properties.
-     *
-     * @param Document\Properties $pValue
      */
-    public function setProperties(Document\Properties $pValue)
+    public function setProperties(Document\Properties $pValue): void
     {
         $this->properties = $pValue;
     }
@@ -560,10 +556,8 @@ class Spreadsheet
 
     /**
      * Set security.
-     *
-     * @param Document\Security $pValue
      */
-    public function setSecurity(Document\Security $pValue)
+    public function setSecurity(Document\Security $pValue): void
     {
         $this->security = $pValue;
     }
@@ -608,7 +602,6 @@ class Spreadsheet
     /**
      * Add sheet.
      *
-     * @param Worksheet $pSheet
      * @param null|int $iSheetIndex Index where sheet should go (0,1,..., or null for last)
      *
      * @return Worksheet
@@ -653,7 +646,7 @@ class Spreadsheet
      *
      * @param int $pIndex Active sheet index
      */
-    public function removeSheetByIndex($pIndex)
+    public function removeSheetByIndex($pIndex): void
     {
         $numSheets = count($this->workSheetCollection);
         if ($pIndex > $numSheets - 1) {
@@ -722,8 +715,6 @@ class Spreadsheet
     /**
      * Get index for sheet.
      *
-     * @param Worksheet $pSheet
-     *
      * @return int index
      */
     public function getIndex(Worksheet $pSheet)
@@ -885,8 +876,6 @@ class Spreadsheet
     /**
      * Add named range.
      *
-     * @param NamedRange $namedRange
-     *
      * @return bool
      */
     public function addNamedRange(NamedRange $namedRange)
@@ -910,7 +899,7 @@ class Spreadsheet
      *
      * @return null|NamedRange
      */
-    public function getNamedRange($namedRange, Worksheet $pSheet = null)
+    public function getNamedRange($namedRange, ?Worksheet $pSheet = null)
     {
         $returnValue = null;
 
@@ -937,7 +926,7 @@ class Spreadsheet
      *
      * @return $this
      */
-    public function removeNamedRange($namedRange, Worksheet $pSheet = null)
+    public function removeNamedRange($namedRange, ?Worksheet $pSheet = null)
     {
         if ($pSheet === null) {
             if (isset($this->namedRanges[$namedRange])) {
@@ -1060,10 +1049,8 @@ class Spreadsheet
 
     /**
      * Add a cellXf to the workbook.
-     *
-     * @param Style $style
      */
-    public function addCellXf(Style $style)
+    public function addCellXf(Style $style): void
     {
         $this->cellXfCollection[] = $style;
         $style->setIndex(count($this->cellXfCollection) - 1);
@@ -1074,7 +1061,7 @@ class Spreadsheet
      *
      * @param int $pIndex Index to cellXf
      */
-    public function removeCellXfByIndex($pIndex)
+    public function removeCellXfByIndex($pIndex): void
     {
         if ($pIndex > count($this->cellXfCollection) - 1) {
             throw new Exception('CellXf index is out of bounds.');
@@ -1151,10 +1138,8 @@ class Spreadsheet
 
     /**
      * Add a cellStyleXf to the workbook.
-     *
-     * @param Style $pStyle
      */
-    public function addCellStyleXf(Style $pStyle)
+    public function addCellStyleXf(Style $pStyle): void
     {
         $this->cellStyleXfCollection[] = $pStyle;
         $pStyle->setIndex(count($this->cellStyleXfCollection) - 1);
@@ -1165,7 +1150,7 @@ class Spreadsheet
      *
      * @param int $pIndex Index to cellXf
      */
-    public function removeCellStyleXfByIndex($pIndex)
+    public function removeCellStyleXfByIndex($pIndex): void
     {
         if ($pIndex > count($this->cellStyleXfCollection) - 1) {
             throw new Exception('CellStyleXf index is out of bounds.');
@@ -1177,7 +1162,7 @@ class Spreadsheet
      * Eliminate all unneeded cellXf and afterwards update the xfIndex for all cells
      * and columns in the workbook.
      */
-    public function garbageCollect()
+    public function garbageCollect(): void
     {
         // how many references are there to each cellXf ?
         $countReferencesCellXf = [];
@@ -1278,7 +1263,7 @@ class Spreadsheet
      *
      * @param bool $showHorizontalScroll True if horizonal scroll bar is visible
      */
-    public function setShowHorizontalScroll($showHorizontalScroll)
+    public function setShowHorizontalScroll($showHorizontalScroll): void
     {
         $this->showHorizontalScroll = (bool) $showHorizontalScroll;
     }
@@ -1298,7 +1283,7 @@ class Spreadsheet
      *
      * @param bool $showVerticalScroll True if vertical scroll bar is visible
      */
-    public function setShowVerticalScroll($showVerticalScroll)
+    public function setShowVerticalScroll($showVerticalScroll): void
     {
         $this->showVerticalScroll = (bool) $showVerticalScroll;
     }
@@ -1318,7 +1303,7 @@ class Spreadsheet
      *
      * @param bool $showSheetTabs True if sheet tabs are visible
      */
-    public function setShowSheetTabs($showSheetTabs)
+    public function setShowSheetTabs($showSheetTabs): void
     {
         $this->showSheetTabs = (bool) $showSheetTabs;
     }
@@ -1338,7 +1323,7 @@ class Spreadsheet
      *
      * @param bool $minimized true if workbook window is minimized
      */
-    public function setMinimized($minimized)
+    public function setMinimized($minimized): void
     {
         $this->minimized = (bool) $minimized;
     }
@@ -1360,7 +1345,7 @@ class Spreadsheet
      *
      * @param bool $autoFilterDateGrouping true if workbook window is minimized
      */
-    public function setAutoFilterDateGrouping($autoFilterDateGrouping)
+    public function setAutoFilterDateGrouping($autoFilterDateGrouping): void
     {
         $this->autoFilterDateGrouping = (bool) $autoFilterDateGrouping;
     }
@@ -1380,7 +1365,7 @@ class Spreadsheet
      *
      * @param int $firstSheetIndex First sheet in book view
      */
-    public function setFirstSheetIndex($firstSheetIndex)
+    public function setFirstSheetIndex($firstSheetIndex): void
     {
         if ($firstSheetIndex >= 0) {
             $this->firstSheetIndex = (int) $firstSheetIndex;
@@ -1417,7 +1402,7 @@ class Spreadsheet
      *
      * @param string $visibility visibility status of the workbook
      */
-    public function setVisibility($visibility)
+    public function setVisibility($visibility): void
     {
         if ($visibility === null) {
             $visibility = self::VISIBILITY_VISIBLE;
@@ -1447,7 +1432,7 @@ class Spreadsheet
      *
      * @param int $tabRatio Ratio between the tabs bar and the horizontal scroll bar
      */
-    public function setTabRatio($tabRatio)
+    public function setTabRatio($tabRatio): void
     {
         if ($tabRatio >= 0 || $tabRatio <= 1000) {
             $this->tabRatio = (int) $tabRatio;