WP_Text_Diff_Renderer_Table::_changed

	public function _changed( $orig, $final ) {
		$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 indix 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 <ins> or <del>'s.
				if ( preg_match_all( '!(<ins>.*?</ins>|<del>.*?</del>)!', $diff, $diff_matches ) ) {
					// Length of all text between <ins> or <del>.
					$stripped_matches = strlen( strip_tags( join( ' ', $diff_matches[0] ) ) );
					// Since we count length of text between <ins> or <del> (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 <del> or <ins>.
				$orig_diffs[ $o ]  = preg_replace( '|<ins>.*?</ins>|', '', $diff );
				$final_diffs[ $f ] = preg_replace( '|<del>.*?</del>|', '', $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 .= '<tr>' . $this->deletedLine( $orig_line ) . $this->emptyLine() . $this->addedLine( $final_line ) . "</tr>\n";
				} else {
					$r .= '<tr>' . $this->deletedLine( $orig_line ) . '</tr><tr>' . $this->addedLine( $final_line ) . "</tr>\n";
				}
			}
		}

		return $r;
	}