DiffUtility.php

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<?php
namespace TYPO3\CMS\Core\Utility;

class DiffUtility {

    // External, static
    // If set, the HTML tags are stripped from the input strings first.
    public $stripTags = 0;

    // Diff options. eg "--unified=3"
    public $diffOptions = '';

    // Internal, dynamic
    // This indicates the number of times the function addClearBuffer has been called - and used to detect the very first call...
    public $clearBufferIdx = 0;

    public $differenceLgd = 0;

    public function makeDiffDisplay($str1, $str2, $wrapTag = 'span') {
        if ($this->stripTags) {
            $str1 = strip_tags($str1);
            $str2 = strip_tags($str2);
        } else {
            $str1 = $this->tagSpace($str1);
            $str2 = $this->tagSpace($str2);
        }
        $str1Lines = $this->explodeStringIntoWords($str1);
        $str2Lines = $this->explodeStringIntoWords($str2);
        $diffRes = $this->getDiff(implode(LF, $str1Lines) . LF, implode(LF, $str2Lines) . LF);
        if (is_array($diffRes)) {
            $c = 0;
            $diffResArray = array();
            $differenceStr = '';
            foreach ($diffRes as $lValue) {
                if ((int)$lValue) {
                    $c = (int)$lValue;
                    $diffResArray[$c]['changeInfo'] = $lValue;
                }
                if ($lValue[0] === '<') {
                    $differenceStr .= ($diffResArray[$c]['old'][] = substr($lValue, 2));
                }
                if ($lValue[0] === '>') {
                    $differenceStr .= ($diffResArray[$c]['new'][] = substr($lValue, 2));
                }
            }
            $this->differenceLgd = strlen($differenceStr);
            $outString = '';
            $clearBuffer = '';
            $str1LinesCount = count($str1Lines);
            for ($a = -1; $a < $str1LinesCount; $a++) {
                if (is_array($diffResArray[$a + 1])) {
                    // a=Add, c=change, d=delete: If a, then the content is Added after the entry and we must insert the line content as well.
                    if (strstr($diffResArray[$a + 1]['changeInfo'], 'a')) {
                        $clearBuffer .= htmlspecialchars($str1Lines[$a]) . ' ';
                    }
                    $outString .= $this->addClearBuffer($clearBuffer);
                    $clearBuffer = '';
                    if (is_array($diffResArray[$a + 1]['old'])) {
                        $outString .= '<' . $wrapTag . ' class="diff-r">' . htmlspecialchars(implode(' ', $diffResArray[($a + 1)]['old'])) . '</' . $wrapTag . '> ';
                    }
                    if (is_array($diffResArray[$a + 1]['new'])) {
                        $outString .= '<' . $wrapTag . ' class="diff-g">' . htmlspecialchars(implode(' ', $diffResArray[($a + 1)]['new'])) . '</' . $wrapTag . '> ';
                    }
                    $chInfParts = explode(',', $diffResArray[$a + 1]['changeInfo']);
                    if ((string)$chInfParts[0] === (string)($a + 1)) {
                        $newLine = (int)$chInfParts[1] - 1;
                        if ($newLine > $a) {
                            $a = $newLine;
                        }
                    }
                } else {
                    $clearBuffer .= htmlspecialchars($str1Lines[$a]) . ' ';
                }
            }
            $outString .= $this->addClearBuffer($clearBuffer, 1);
            $outString = str_replace('  ', LF, $outString);
            if (!$this->stripTags) {
                $outString = $this->tagSpace($outString, 1);
            }
            return $outString;
        }
    }

    public function getDiff($str1, $str2) {
        // Create file 1 and write string
        $file1 = \TYPO3\CMS\Core\Utility\GeneralUtility::tempnam('diff1_');
        \TYPO3\CMS\Core\Utility\GeneralUtility::writeFile($file1, $str1);
        // Create file 2 and write string
        $file2 = \TYPO3\CMS\Core\Utility\GeneralUtility::tempnam('diff2_');
        \TYPO3\CMS\Core\Utility\GeneralUtility::writeFile($file2, $str2);
        // Perform diff.
        $cmd = $GLOBALS['TYPO3_CONF_VARS']['BE']['diff_path'] . ' ' . $this->diffOptions . ' ' . $file1 . ' ' . $file2;
        $res = array();
        \TYPO3\CMS\Core\Utility\CommandUtility::exec($cmd, $res);
        unlink($file1);
        unlink($file2);
        return $res;
    }

    public function addClearBuffer($clearBuffer, $last = 0) {
        if (strlen($clearBuffer) > 200) {
            $clearBuffer = ($this->clearBufferIdx ? \TYPO3\CMS\Core\Utility\GeneralUtility::fixed_lgd_cs($clearBuffer, 70) : '') . '[' . strlen($clearBuffer) . ']' . (!$last ? \TYPO3\CMS\Core\Utility\GeneralUtility::fixed_lgd_cs($clearBuffer, -70) : '');
        }
        $this->clearBufferIdx++;
        return $clearBuffer;
    }

    public function explodeStringIntoWords($str) {
        $strArr = \TYPO3\CMS\Core\Utility\GeneralUtility::trimExplode(LF, $str);
        $outArray = array();
        foreach ($strArr as $lineOfWords) {
            $allWords = \TYPO3\CMS\Core\Utility\GeneralUtility::trimExplode(' ', $lineOfWords, TRUE);
            $outArray[] = $allWords;
            $outArray[] = array('');
            $outArray[] = array('');
        }
        return call_user_func_array('array_merge', $outArray);
    }

    public function tagSpace($str, $rev = 0) {
        if ($rev) {
            return str_replace(' &lt;', '&lt;', str_replace('&gt; ', '&gt;', $str));
        } else {
            return str_replace('<', ' <', str_replace('>', '> ', $str));
        }
    }

}