Title: WP_Text_Diff_Renderer_Table Published: April 25, 2014 Last modified: August 20, 2026 --- # class WP_Text_Diff_Renderer_Table {} ## In this article * [Methods](https://developer.wordpress.org/reference/classes/WP_Text_Diff_Renderer_Table/?output_format=md#methods) * [Source](https://developer.wordpress.org/reference/classes/WP_Text_Diff_Renderer_Table/?output_format=md#source) * [Changelog](https://developer.wordpress.org/reference/classes/WP_Text_Diff_Renderer_Table/?output_format=md#changelog) [ Back to top](https://developer.wordpress.org/reference/classes/WP_Text_Diff_Renderer_Table/?output_format=md#wp--skip-link--target) Table renderer to display the diff lines. ## 󠀁[Methods](https://developer.wordpress.org/reference/classes/WP_Text_Diff_Renderer_Table/?output_format=md#methods)󠁿 | Name | Description | | [WP_Text_Diff_Renderer_Table::__construct](https://developer.wordpress.org/reference/classes/wp_text_diff_renderer_table/__construct/) | Constructor – Call parent constructor with params array. | | [WP_Text_Diff_Renderer_Table::__get](https://developer.wordpress.org/reference/classes/wp_text_diff_renderer_table/__get/) | Make private properties readable for backward compatibility. | | [WP_Text_Diff_Renderer_Table::__isset](https://developer.wordpress.org/reference/classes/wp_text_diff_renderer_table/__isset/) | Make private properties checkable for backward compatibility. | | [WP_Text_Diff_Renderer_Table::__set](https://developer.wordpress.org/reference/classes/wp_text_diff_renderer_table/__set/) | Make private properties settable for backward compatibility. | | [WP_Text_Diff_Renderer_Table::__unset](https://developer.wordpress.org/reference/classes/wp_text_diff_renderer_table/__unset/) | Make private properties un-settable for backward compatibility. | | [WP_Text_Diff_Renderer_Table::_changed](https://developer.wordpress.org/reference/classes/wp_text_diff_renderer_table/_changed/) | Process changed lines to do word-by-word diffs for extra highlighting. | | [WP_Text_Diff_Renderer_Table::compute_string_distance](https://developer.wordpress.org/reference/classes/wp_text_diff_renderer_table/compute_string_distance/) | Computes a number that is intended to reflect the “distance” between two strings. | | [WP_Text_Diff_Renderer_Table::interleave_changed_lines](https://developer.wordpress.org/reference/classes/wp_text_diff_renderer_table/interleave_changed_lines/) | Takes changed blocks and matches which rows in orig turned into which rows in final. | ## 󠀁[Source](https://developer.wordpress.org/reference/classes/WP_Text_Diff_Renderer_Table/?output_format=md#source)󠁿 ```php #[AllowDynamicProperties] class WP_Text_Diff_Renderer_Table extends Text_Diff_Renderer { /** * @see Text_Diff_Renderer::_leading_context_lines * @var int * @since 2.6.0 */ public $_leading_context_lines = 10000; /** * @see Text_Diff_Renderer::_trailing_context_lines * @var int * @since 2.6.0 */ public $_trailing_context_lines = 10000; /** * Title of the item being compared. * * @since 6.4.0 Declared a previously dynamic property. * @var string|null */ public $_title; /** * Title for the left column. * * @since 6.4.0 Declared a previously dynamic property. * @var string|null */ public $_title_left; /** * Title for the right column. * * @since 6.4.0 Declared a previously dynamic property. * @var string|null */ public $_title_right; /** * Threshold for when a diff should be saved or omitted. * * @var float * @since 2.6.0 */ protected $_diff_threshold = 0.6; /** * Inline display helper object name. * * @var string * @since 2.6.0 */ protected $inline_diff_renderer = 'WP_Text_Diff_Renderer_inline'; /** * Should we show the split view or not * * @var string * @since 3.6.0 */ protected $_show_split_view = true; protected $compat_fields = array( '_show_split_view', 'inline_diff_renderer', '_diff_threshold' ); /** * Caches the output of count_chars() in compute_string_distance() * * @var array * @since 5.0.0 */ protected $count_cache = array(); /** * Caches the difference calculation in compute_string_distance() * * @var array * @since 5.0.0 */ protected $difference_cache = array(); /** * Constructor - Call parent constructor with params array. * * This will set class properties based on the key value pairs in the array. * * @since 2.6.0 * * @param array $params */ public function __construct( $params = array() ) { parent::__construct( $params ); if ( isset( $params['show_split_view'] ) ) { $this->_show_split_view = $params['show_split_view']; } } /** * @ignore * * @param string $header * @return string */ public function _startBlock( $header ) { return ''; } /** * @ignore * * @param array $lines * @param string $prefix */ public function _lines( $lines, $prefix = ' ' ) { } /** * @ignore * * @param string $line HTML-escape the value. * @return string */ public function addedLine( $line ) { return "" . /* translators: Hidden accessibility text. */ __( 'Added:' ) . " {$line}"; } /** * @ignore * * @param string $line HTML-escape the value. * @return string */ public function deletedLine( $line ) { return "" . /* translators: Hidden accessibility text. */ __( 'Deleted:' ) . " {$line}"; } /** * @ignore * * @param string $line HTML-escape the value. * @return string */ public function contextLine( $line ) { return "" . /* translators: Hidden accessibility text. */ __( 'Unchanged:' ) . " {$line}"; } /** * @ignore * * @return string */ public function emptyLine() { return ' '; } /** * @ignore * * @param array $lines * @param bool $encode * @return string */ public function _added( $lines, $encode = true ) { $r = ''; foreach ( $lines as $line ) { if ( $encode ) { $processed_line = htmlspecialchars( $line ); /** * Contextually filters a diffed line. * * Filters TextDiff processing of diffed line. By default, diffs are processed with * htmlspecialchars. Use this filter to remove or change the processing. Passes a context * indicating if the line is added, deleted or unchanged. * * @since 4.1.0 * * @param string $processed_line The processed diffed line. * @param string $line The unprocessed diffed line. * @param string $context The line context. Values are 'added', 'deleted' or 'unchanged'. */ $line = apply_filters( 'process_text_diff_html', $processed_line, $line, 'added' ); } if ( $this->_show_split_view ) { $r .= '' . $this->emptyLine() . $this->addedLine( $line ) . "\n"; } else { $r .= '' . $this->addedLine( $line ) . "\n"; } } return $r; } /** * @ignore * * @param array $lines * @param bool $encode * @return string */ public function _deleted( $lines, $encode = true ) { $r = ''; foreach ( $lines as $line ) { if ( $encode ) { $processed_line = htmlspecialchars( $line ); /** This filter is documented in wp-includes/class-wp-text-diff-renderer-table.php */ $line = apply_filters( 'process_text_diff_html', $processed_line, $line, 'deleted' ); } if ( $this->_show_split_view ) { $r .= '' . $this->deletedLine( $line ) . $this->emptyLine() . "\n"; } else { $r .= '' . $this->deletedLine( $line ) . "\n"; } } return $r; } /** * @ignore * * @param array $lines * @param bool $encode * @return string */ public function _context( $lines, $encode = true ) { $r = ''; foreach ( $lines as $line ) { if ( $encode ) { $processed_line = htmlspecialchars( $line ); /** This filter is documented in wp-includes/class-wp-text-diff-renderer-table.php */ $line = apply_filters( 'process_text_diff_html', $processed_line, $line, 'unchanged' ); } if ( $this->_show_split_view ) { $r .= '' . $this->contextLine( $line ) . $this->contextLine( $line ) . "\n"; } else { $r .= '' . $this->contextLine( $line ) . "\n"; } } return $r; } /** * Process changed lines to do word-by-word diffs for extra highlighting. * * (TRAC style) sometimes these lines can actually be deleted or added rows. * We do additional processing to figure that out * * @since 2.6.0 * * @param array $orig * @param array $final * @return string */ public function _changed( $orig, $final ) { // phpcs:ignore Universal.NamingConventions.NoReservedKeywordParameterNames.finalFound $r = ''; /* * Does the aforementioned additional processing: * *_matches tell what rows are "the same" in orig and final. Those pairs will be diffed to get word changes. * - match is numeric: an index in other column. * - match is 'X': no match. It is a new row. * *_rows are column vectors for the orig column and the final column. * - row >= 0: an index of the $orig or $final array. * - row < 0: a blank row for that column. */ list($orig_matches, $final_matches, $orig_rows, $final_rows) = $this->interleave_changed_lines( $orig, $final ); // These will hold the word changes as determined by an inline diff. $orig_diffs = array(); $final_diffs = array(); // Compute word diffs for each matched pair using the inline diff. foreach ( $orig_matches as $o => $f ) { if ( is_numeric( $o ) && is_numeric( $f ) ) { $text_diff = new Text_Diff( 'auto', array( array( $orig[ $o ] ), array( $final[ $f ] ) ) ); $renderer = new $this->inline_diff_renderer(); $diff = $renderer->render( $text_diff ); // If they're too different, don't include any or 's. if ( preg_match_all( '!(.*?|.*?)!', $diff, $diff_matches ) ) { // Length of all text between or . $stripped_matches = strlen( strip_tags( implode( ' ', $diff_matches[0] ) ) ); /* * Since we count length of text between or (instead of picking just one), * we double the length of chars not in those tags. */ $stripped_diff = strlen( strip_tags( $diff ) ) * 2 - $stripped_matches; $diff_ratio = $stripped_matches / $stripped_diff; if ( $diff_ratio > $this->_diff_threshold ) { continue; // Too different. Don't save diffs. } } // Un-inline the diffs by removing or . $orig_diffs[ $o ] = preg_replace( '|.*?|', '', $diff ); $final_diffs[ $f ] = preg_replace( '|.*?|', '', $diff ); } } foreach ( array_keys( $orig_rows ) as $row ) { // Both columns have blanks. Ignore them. if ( $orig_rows[ $row ] < 0 && $final_rows[ $row ] < 0 ) { continue; } // If we have a word based diff, use it. Otherwise, use the normal line. if ( isset( $orig_diffs[ $orig_rows[ $row ] ] ) ) { $orig_line = $orig_diffs[ $orig_rows[ $row ] ]; } elseif ( isset( $orig[ $orig_rows[ $row ] ] ) ) { $orig_line = htmlspecialchars( $orig[ $orig_rows[ $row ] ] ); } else { $orig_line = ''; } if ( isset( $final_diffs[ $final_rows[ $row ] ] ) ) { $final_line = $final_diffs[ $final_rows[ $row ] ]; } elseif ( isset( $final[ $final_rows[ $row ] ] ) ) { $final_line = htmlspecialchars( $final[ $final_rows[ $row ] ] ); } else { $final_line = ''; } if ( $orig_rows[ $row ] < 0 ) { // Orig is blank. This is really an added row. $r .= $this->_added( array( $final_line ), false ); } elseif ( $final_rows[ $row ] < 0 ) { // Final is blank. This is really a deleted row. $r .= $this->_deleted( array( $orig_line ), false ); } else { // A true changed row. if ( $this->_show_split_view ) { $r .= '' . $this->deletedLine( $orig_line ) . $this->addedLine( $final_line ) . "\n"; } else { $r .= '' . $this->deletedLine( $orig_line ) . '' . $this->addedLine( $final_line ) . "\n"; } } } return $r; } /** * Takes changed blocks and matches which rows in orig turned into which rows in final. * * @since 2.6.0 * * @param array $orig Lines of the original version of the text. * @param array $final Lines of the final version of the text. * @return array { * Array containing results of comparing the original text to the final text. * * @type array $orig_matches Associative array of original matches. Index == row * number of `$orig`, value == corresponding row number * of that same line in `$final` or 'x' if there is no * corresponding row (indicating it is a deleted line). * @type array $final_matches Associative array of final matches. Index == row * number of `$final`, value == corresponding row number * of that same line in `$orig` or 'x' if there is no * corresponding row (indicating it is a new line). * @type array $orig_rows Associative array of interleaved rows of `$orig` with * blanks to keep matches aligned with side-by-side diff * of `$final`. A value >= 0 corresponds to index of `$orig`. * Value < 0 indicates a blank row. * @type array $final_rows Associative array of interleaved rows of `$final` with * blanks to keep matches aligned with side-by-side diff * of `$orig`. A value >= 0 corresponds to index of `$final`. * Value < 0 indicates a blank row. * } */ public function interleave_changed_lines( $orig, $final ) { // phpcs:ignore Universal.NamingConventions.NoReservedKeywordParameterNames.finalFound // Contains all pairwise string comparisons. Keys are such that this need only be a one dimensional array. $matches = array(); foreach ( array_keys( $orig ) as $o ) { foreach ( array_keys( $final ) as $f ) { $matches[ "$o,$f" ] = $this->compute_string_distance( $orig[ $o ], $final[ $f ] ); } } asort( $matches ); // Order by string distance. $orig_matches = array(); $final_matches = array(); foreach ( $matches as $keys => $difference ) { list($o, $f) = explode( ',', $keys ); $o = (int) $o; $f = (int) $f; // Already have better matches for these guys. if ( isset( $orig_matches[ $o ] ) && isset( $final_matches[ $f ] ) ) { continue; } // First match for these guys. Must be best match. if ( ! isset( $orig_matches[ $o ] ) && ! isset( $final_matches[ $f ] ) ) { $orig_matches[ $o ] = $f; $final_matches[ $f ] = $o; continue; } // Best match of this final is already taken? Must mean this final is a new row. if ( isset( $orig_matches[ $o ] ) ) { $final_matches[ $f ] = 'x'; } elseif ( isset( $final_matches[ $f ] ) ) { // Best match of this orig is already taken? Must mean this orig is a deleted row. $orig_matches[ $o ] = 'x'; } } // We read the text in this order. ksort( $orig_matches ); ksort( $final_matches ); // Stores rows and blanks for each column. $orig_rows = array_keys( $orig_matches ); $orig_rows_copy = $orig_rows; $final_rows = array_keys( $final_matches ); /* * Interleaves rows with blanks to keep matches aligned. * We may end up with some extraneous blank rows, but we'll just ignore them later. */ foreach ( $orig_rows_copy as $orig_row ) { $final_pos = array_search( $orig_matches[ $orig_row ], $final_rows, true ); $orig_pos = (int) array_search( $orig_row, $orig_rows, true ); if ( false === $final_pos ) { // This orig is paired with a blank final. array_splice( $final_rows, $orig_pos, 0, -1 ); } elseif ( $final_pos < $orig_pos ) { // This orig's match is up a ways. Pad final with blank rows. $diff_array = range( -1, $final_pos - $orig_pos ); array_splice( $final_rows, $orig_pos, 0, $diff_array ); } elseif ( $final_pos > $orig_pos ) { // This orig's match is down a ways. Pad orig with blank rows. $diff_array = range( -1, $orig_pos - $final_pos ); array_splice( $orig_rows, $orig_pos, 0, $diff_array ); } } // Pad the ends with blank rows if the columns aren't the same length. $diff_count = count( $orig_rows ) - count( $final_rows ); if ( $diff_count < 0 ) { while ( $diff_count < 0 ) { array_push( $orig_rows, $diff_count++ ); } } elseif ( $diff_count > 0 ) { $diff_count = -1 * $diff_count; while ( $diff_count < 0 ) { array_push( $final_rows, $diff_count++ ); } } return array( $orig_matches, $final_matches, $orig_rows, $final_rows ); } /** * Computes a number that is intended to reflect the "distance" between two strings. * * @since 2.6.0 * * @param string $string1 * @param string $string2 * @return int */ public function compute_string_distance( $string1, $string2 ) { // Use an md5 hash of the strings for a count cache, as it's fast to generate, and collisions aren't a concern. $count_key1 = md5( $string1 ); $count_key2 = md5( $string2 ); // Cache vectors containing character frequency for all chars in each string. if ( ! isset( $this->count_cache[ $count_key1 ] ) ) { $this->count_cache[ $count_key1 ] = count_chars( $string1 ); } if ( ! isset( $this->count_cache[ $count_key2 ] ) ) { $this->count_cache[ $count_key2 ] = count_chars( $string2 ); } $chars1 = $this->count_cache[ $count_key1 ]; $chars2 = $this->count_cache[ $count_key2 ]; $difference_key = md5( implode( ',', $chars1 ) . ':' . implode( ',', $chars2 ) ); if ( ! isset( $this->difference_cache[ $difference_key ] ) ) { // L1-norm of difference vector. $this->difference_cache[ $difference_key ] = array_sum( array_map( array( $this, 'difference' ), $chars1, $chars2 ) ); } $difference = $this->difference_cache[ $difference_key ]; // $string1 has zero length? Odd. Give huge penalty by not dividing. if ( ! $string1 ) { return $difference; } // Return distance per character (of string1). return $difference / strlen( $string1 ); } /** * @ignore * @since 2.6.0 * * @param int $a * @param int $b * @return int */ public function difference( $a, $b ) { return abs( $a - $b ); } /** * Make private properties readable for backward compatibility. * * @since 4.0.0 * @since 6.4.0 Getting a dynamic property is deprecated. * * @param string $name Property to get. * @return mixed A declared property's value, else null. */ public function __get( $name ) { if ( in_array( $name, $this->compat_fields, true ) ) { return $this->$name; } wp_trigger_error( __METHOD__, "The property `{$name}` is not declared. Getting a dynamic property is " . 'deprecated since version 6.4.0! Instead, declare the property on the class.', E_USER_DEPRECATED ); return null; } /** * Make private properties settable for backward compatibility. * * @since 4.0.0 * @since 6.4.0 Setting a dynamic property is deprecated. * * @param string $name Property to check if set. * @param mixed $value Property value. */ public function __set( $name, $value ) { if ( in_array( $name, $this->compat_fields, true ) ) { $this->$name = $value; return; } wp_trigger_error( __METHOD__, "The property `{$name}` is not declared. Setting a dynamic property is " . 'deprecated since version 6.4.0! Instead, declare the property on the class.', E_USER_DEPRECATED ); } /** * Make private properties checkable for backward compatibility. * * @since 4.0.0 * @since 6.4.0 Checking a dynamic property is deprecated. * * @param string $name Property to check if set. * @return bool Whether the property is set. */ public function __isset( $name ) { if ( in_array( $name, $this->compat_fields, true ) ) { return isset( $this->$name ); } wp_trigger_error( __METHOD__, "The property `{$name}` is not declared. Checking `isset()` on a dynamic property " . 'is deprecated since version 6.4.0! Instead, declare the property on the class.', E_USER_DEPRECATED ); return false; } /** * Make private properties un-settable for backward compatibility. * * @since 4.0.0 * @since 6.4.0 Unsetting a dynamic property is deprecated. * * @param string $name Property to unset. */ public function __unset( $name ) { if ( in_array( $name, $this->compat_fields, true ) ) { unset( $this->$name ); return; } wp_trigger_error( __METHOD__, "A property `{$name}` is not declared. Unsetting a dynamic property is " . 'deprecated since version 6.4.0! Instead, declare the property on the class.', E_USER_DEPRECATED ); } } ``` [View all references](https://developer.wordpress.org/reference/files/wp-includes/class-wp-text-diff-renderer-table.php/) [View on Trac](https://core.trac.wordpress.org/browser/tags/7.1/src/wp-includes/class-wp-text-diff-renderer-table.php#L21) [View on GitHub](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/class-wp-text-diff-renderer-table.php#L21-L628) ## 󠀁[Changelog](https://developer.wordpress.org/reference/classes/WP_Text_Diff_Renderer_Table/?output_format=md#changelog)󠁿 | Version | Description | | [2.6.0](https://developer.wordpress.org/reference/since/2.6.0/) | Introduced. | ## User Contributed Notes You must [log in](https://login.wordpress.org/?redirect_to=https%3A%2F%2Fdeveloper.wordpress.org%2Freference%2Fclasses%2Fwp_text_diff_renderer_table%2F) before being able to contribute a note or feedback.