Text_Diff_Engine_native

Complexity

Total Complexity

95

Size/Duplication

Total Lines	536
Duplicated Lines	2.05 %

Coupling/Cohesion

Components	1
Dependencies	4

Importance

Changes

0

5 Methods

Rating	Name	Duplication	Size	Complexity
F	diff()	0	132	29
F	_diag()	11	104	20
A	_lcsPos()	0	34	5
C	_compareseq()	0	57	13
F	_shiftBoundaries()	0	135	28

<?php

/**
 * Text_Diff
 *
 * General API for generating and formatting diffs - the differences between
 * two sequences of strings.
 *
 * The PHP diff code used in this package was originally written by Geoffrey
 * T. Dairiki and is used with his permission.
 *
 * $Horde: framework/Text_Diff/Diff.php,v 1.13 2005/05/26 20:26:06 selsky Exp $
 *
 * @package Text_Diff
 * @author  Geoffrey T. Dairiki <dairiki@dairiki.org>
 */
class Text_Diff
{
    /**
     * Array of changes.
     *
     * @var array
     */

    public $_edits;

    /**
     * Computes diffs between sequences of strings.
     *
     * @param array $from_lines  An array of strings.  Typically these are
     *                           lines from a file.
     * @param array $to_lines    An array of strings.
     */

    //HACK by domifara

    //  function Text_Diff($from_lines, $to_lines)

    public function __construct($from_lines, $to_lines)
    {
        array_walk($from_lines, [$this, '_trimNewlines']);

        array_walk($to_lines, [$this, '_trimNewlines']);

        if (extension_loaded('xdiff')) {
            $engine = new Text_Diff_Engine_xdiff();
        } else {
            $engine = new Text_Diff_Engine_native();
        }

        $this->_edits = $engine->diff($from_lines, $to_lines);
    }

    /**
     * Returns the array of differences.
     */

    public function getDiff()
    {
        return $this->_edits;
    }

    /**
     * Computes a reversed diff.
     *
     * Example:
     * <code>
     * $diff = new Text_Diff($lines1, $lines2);
     * $rev = $diff->reverse();
     * </code>
     *
     * @return Text_Diff  A Diff object representing the inverse of the
     *                    original diff.  Note that we purposely don't return a
     *                    reference here, since this essentially is a clone()
     *                    method.
     */

    public function reverse()
    {
        if (version_compare(zend_version(), '2', '>')) {
            $rev = clone$obj;

The variable $obj does not exist. Did you forget to declare it?

        } else {
            $rev = $this;
        }

        $rev->_edits = [];

        foreach ($this->_edits as $edit) {
            $rev->_edits[] = $edit->reverse();
        }

        return $rev;
    }

    /**
     * Checks for an empty diff.
     *
     * @return bool  True if two sequences were identical.
     */

    public function isEmpty()
    {
        foreach ($this->_edits as $edit) {
            if (!is_a($edit, 'Text_Diff_Op_copy')) {
                return false;
            }
        }

        return true;
    }

    /**
     * Computes the length of the Longest Common Subsequence (LCS).
     *
     * This is mostly for diagnostic purposes.
     *
     * @return int  The length of the LCS.
     */

    public function lcs()
    {
        $lcs = 0;

        foreach ($this->_edits as $edit) {
            if (is_a($edit, 'Text_Diff_Op_copy')) {
                $lcs += count($edit->orig);
            }
        }

        return $lcs;
    }

    /**
     * Gets the original set of lines.
     *
     * This reconstructs the $from_lines parameter passed to the constructor.
     *
     * @return array  The original sequence of strings.
     */

    public function getOriginal()

This method seems to be duplicated in your project.

    {
        $lines = [];

        foreach ($this->_edits as $edit) {
            if ($edit->orig) {
                array_splice($lines, count($lines), 0, $edit->orig);
            }
        }

        return $lines;
    }

    /**
     * Gets the final set of lines.
     *
     * This reconstructs the $to_lines parameter passed to the constructor.
     *
     * @return array  The sequence of strings.
     */

    public function getFinal()

This method seems to be duplicated in your project.

    {
        $lines = [];

        foreach ($this->_edits as $edit) {
            if ($edit->final) {
                array_splice($lines, count($lines), 0, $edit->final);
            }
        }

        return $lines;
    }

    /**
     * Removes trailing newlines from a line of text. This is meant to be used
     * with array_walk().
     *
     * @param string  $line The line to trim.
     * @param int $key  The index of the line in the array. Not used.
     */

    public function _trimNewlines(&$line, $key)

The parameter $key is not used and could be removed.

    {
        $line = str_replace(["\n", "\r"], '', $line);
    }

    /**
     * Checks a diff for validity.
     *
     * This is here only for debugging purposes.
     * @param $from_lines
     * @param $to_lines
     * @return bool
     */

    public function _check($from_lines, $to_lines)
    {
        if (serialize($from_lines) != serialize($this->getOriginal())) {
            trigger_error("Reconstructed original doesn't match", E_USER_ERROR);
        }

        if (serialize($to_lines) != serialize($this->getFinal())) {
            trigger_error("Reconstructed final doesn't match", E_USER_ERROR);
        }

        $rev = $this->reverse();

        if (serialize($to_lines) != serialize($rev->getOriginal())) {
            trigger_error("Reversed original doesn't match", E_USER_ERROR);
        }

        if (serialize($from_lines) != serialize($rev->getFinal())) {
            trigger_error("Reversed final doesn't match", E_USER_ERROR);
        }

        $prevtype = null;

        foreach ($this->_edits as $edit) {
            if ($prevtype == get_class($edit)) {
                trigger_error('Edit sequence is non-optimal', E_USER_ERROR);
            }

            $prevtype = get_class($edit);
        }

        return true;
    }
}

/**
 * $Horde: framework/Text_Diff/Diff.php,v 1.13 2005/05/26 20:26:06 selsky Exp $
 *
 * @package Text_Diff
 * @author  Geoffrey T. Dairiki <dairiki@dairiki.org>
 */
class Text_MappedDiff extends Text_Diff
{
    /**
     * Computes a diff between sequences of strings.
     *
     * This can be used to compute things like case-insensitve diffs, or diffs
     * which ignore changes in white-space.
     *
     * @param array $from_lines         An array of strings.
     * @param array $to_lines           An array of strings.
     * @param array $mapped_from_lines  This array should have the same size
     *                                  number of elements as $from_lines.  The
     *                                  elements in $mapped_from_lines and
     *                                  $mapped_to_lines are what is actually
     *                                  compared when computing the diff.
     * @param array $mapped_to_lines    This array should have the same number
     *                                  of elements as $to_lines.
     */

    public function __construct(
        $from_lines,
        $to_lines,
        $mapped_from_lines,
        $mapped_to_lines
    ) {
        assert(count($from_lines) == count($mapped_from_lines));

        assert(count($to_lines) == count($mapped_to_lines));

        parent::__construct($mapped_from_lines, $mapped_to_lines);

        $xi = $yi = 0;

        for ($i = 0; $i < count($this->_edits); ++$i) {

It seems like you are calling the size function count() as part of the test condition. You might want to compute the size beforehand, and not on each iteration.

            $orig = &$this->_edits[$i]->orig;

            if (is_array($orig)) {
                $orig = array_slice($from_lines, $xi, count($orig));

                $xi += count($orig);
            }

            $final = &$this->_edits[$i]->final;

            if (is_array($final)) {
                $final = array_slice($to_lines, $yi, count($final));

                $yi += count($final);
            }
        }
    }
}

/**
 * Class used internally by Diff to actually compute the diffs.  This class
 * uses the xdiff PECL package (https://pecl.php.net/package/xdiff) to compute
 * the differences between the two input arrays.
 *
 * @author  Jon Parise <jon@horde.org>
 * @package Text_Diff
 *
 * @access  private
 */
class Text_Diff_Engine_xdiff
{
    /**
     * @param $from_lines
     * @param $to_lines
     * @return array
     */

    public function diff($from_lines, $to_lines)
    {
        /* Convert the two input arrays into strings for xdiff processing. */

        $from_string = implode("\n", $from_lines);

        $to_string = implode("\n", $to_lines);

        /* Diff the two strings and convert the result to an array. */

        $diff = xdiff_string_diff($from_string, $to_string, count($to_lines));

        $diff = explode("\n", $diff);

        /* Walk through the diff one line at a time.  We build the $edits
         * array of diff operations by reading the first character of the
         * xdiff output (which is in the "unified diff" format).
         *
         * Note that we don't have enough information to detect "changed"
         * lines using this approach, so we can't add Text_Diff_Op_changed
         * instances to the $edits array.  The result is still perfectly
         * valid, albeit a little less descriptive and efficient. */

        $edits = [];

        foreach ($diff as $line) {
            switch ($line[0]) {
                case ' ':
                    $edits[] = new Text_Diff_Op_copy([mb_substr($line, 1)]);
                    break;
                case '+':
                    $edits[] = new Text_Diff_Op_add([mb_substr($line, 1)]);
                    break;
                case '-':
                    $edits[] = new Text_Diff_Op_delete([mb_substr($line, 1)]);
                    break;
            }
        }

        return $edits;
    }
}

/**
 * Class used internally by Diff to actually compute the diffs.  This class is
 * implemented using native PHP code.
 *
 * The algorithm used here is mostly lifted from the perl module
 * Algorithm::Diff (version 1.06) by Ned Konz, which is available at:
 * https://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
 *
 * More ideas are taken from:
 * https://www.ics.uci.edu/~eppstein/161/960229.html
 *
 * Some ideas (and a bit of code) are taken from analyze.c, of GNU
 * diffutils-2.7, which can be found at:
 * ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz
 *
 * Some ideas (subdivision by NCHUNKS > 2, and some optimizations) are from
 * Geoffrey T. Dairiki <dairiki@dairiki.org>. The original PHP version of this
 * code was written by him, and is used/adapted with his permission.
 *
 * @author  Geoffrey T. Dairiki <dairiki@dairiki.org>
 * @package Text_Diff
 *
 * @access  private
 */
class Text_Diff_Engine_native
{
    /**
     * @param $from_lines
     * @param $to_lines
     * @return array
     */

    public function diff($from_lines, $to_lines)
    {
        $n_from = count($from_lines);

        $n_to = count($to_lines);

        $this->xchanged = $this->ychanged = [];

The property ychanged does not exist. Did you maybe forget to declare it?

The property xchanged does not exist. Did you maybe forget to declare it?

        $this->xv = $this->yv = [];

The property xv does not exist. Did you maybe forget to declare it?

The property yv does not exist. Did you maybe forget to declare it?

        $this->xind = $this->yind = [];

The property xind does not exist. Did you maybe forget to declare it?

The property yind does not exist. Did you maybe forget to declare it?

        unset($this->seq, $this->in_seq, $this->lcs);

        // Skip leading common lines.

        for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++) {
            if ($from_lines[$skip] != $to_lines[$skip]) {
                break;
            }

            $this->xchanged[$skip] = $this->ychanged[$skip] = false;
        }

        // Skip trailing common lines.

        $xi = $n_from;

        $yi = $n_to;

        for ($endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++) {
            if ($from_lines[$xi] != $to_lines[$yi]) {
                break;
            }

            $this->xchanged[$xi] = $this->ychanged[$yi] = false;
        }

        // Ignore lines which do not exist in both files.

        for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
            $xhash[$from_lines[$xi]] = 1;

$xhash was never initialized. Although not strictly required by PHP, it is generally a good practice to add $xhash = array(); before regardless.

        }

        for ($yi = $skip; $yi < $n_to - $endskip; $yi++) {
            $line = $to_lines[$yi];

            if ($this->ychanged[$yi] = empty($xhash[$line])) {
                continue;
            }

            $yhash[$line] = 1;

$yhash was never initialized. Although not strictly required by PHP, it is generally a good practice to add $yhash = array(); before regardless.

            $this->yv[] = $line;

            $this->yind[] = $yi;
        }

        for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
            $line = $from_lines[$xi];

            if ($this->xchanged[$xi] = empty($yhash[$line])) {
                continue;
            }

            $this->xv[] = $line;

            $this->xind[] = $xi;
        }

        // Find the LCS.

        $this->_compareseq(0, count($this->xv), 0, count($this->yv));

        // Merge edits when possible.

        $this->_shiftBoundaries($from_lines, $this->xchanged, $this->ychanged);

        $this->_shiftBoundaries($to_lines, $this->ychanged, $this->xchanged);

        // Compute the edit operations.

        $edits = [];

        $xi = $yi = 0;

        while ($xi < $n_from || $yi < $n_to) {
            assert($yi < $n_to || $this->xchanged[$xi]);

            assert($xi < $n_from || $this->ychanged[$yi]);

            // Skip matching "snake".

            $copy = [];

            while ($xi < $n_from && $yi < $n_to
                   && !$this->xchanged[$xi]
                   && !$this->ychanged[$yi]) {
                $copy[] = $from_lines[$xi++];

                ++$yi;
            }

            if ($copy) {

The expression $copy of type array is implicitly converted to a boolean; are you sure this is intended? If so, consider using ! empty($expr) instead to make it clear that you intend to check for an array without elements.

                $edits[] = new Text_Diff_Op_copy($copy);
            }

            // Find deletes & adds.

            $delete = [];

            while ($xi < $n_from && $this->xchanged[$xi]) {
                $delete[] = $from_lines[$xi++];
            }

            $add = [];

            while ($yi < $n_to && $this->ychanged[$yi]) {
                $add[] = $to_lines[$yi++];
            }

            if ($delete && $add) {

The expression $delete of type array is implicitly converted to a boolean; are you sure this is intended? If so, consider using ! empty($expr) instead to make it clear that you intend to check for an array without elements.

The expression $add of type array is implicitly converted to a boolean; are you sure this is intended? If so, consider using ! empty($expr) instead to make it clear that you intend to check for an array without elements.

                $edits[] = new Text_Diff_Op_change($delete, $add);
            } elseif ($delete) {

The expression $delete of type array is implicitly converted to a boolean; are you sure this is intended? If so, consider using ! empty($expr) instead to make it clear that you intend to check for an array without elements.

                $edits[] = new Text_Diff_Op_delete($delete);
            } elseif ($add) {

The expression $add of type array is implicitly converted to a boolean; are you sure this is intended? If so, consider using ! empty($expr) instead to make it clear that you intend to check for an array without elements.

                $edits[] = new Text_Diff_Op_add($add);
            }
        }

        return $edits;
    }

    /**
     * Divides the Largest Common Subsequence (LCS) of the sequences (XOFF,
     * XLIM) and (YOFF, YLIM) into NCHUNKS approximately equally sized
     * segments.
     *
     * Returns (LCS, PTS).  LCS is the length of the LCS. PTS is an array of
     * NCHUNKS+1 (X, Y) indexes giving the diving points between sub
     * sequences.  The first sub-sequence is contained in (X0, X1), (Y0, Y1),
     * the second in (X1, X2), (Y1, Y2) and so on.  Note that (X0, Y0) ==
     * (XOFF, YOFF) and (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM).
     *
     * This function assumes that the first lines of the specified portions of
     * the two files do not match, and likewise that the last lines do not
     * match.  The caller must trim matching lines from the beginning and end
     * of the portions it is going to specify.
     * @param $xoff
     * @param $xlim
     * @param $yoff
     * @param $ylim
     * @param $nchunks
     * @return array
     */

    public function _diag($xoff, $xlim, $yoff, $ylim, $nchunks)
    {
        $flip = false;

        if ($xlim - $xoff > $ylim - $yoff) {
            /* Things seems faster (I'm not sure I understand why) when the
             * shortest sequence is in X. */

            $flip = true;

            list($xoff, $xlim, $yoff, $ylim) = [$yoff, $ylim, $xoff, $xlim];
        }

        if ($flip) {
            for ($i = $ylim - 1; $i >= $yoff; $i--) {
                $ymatches[$this->xv[$i]][] = $i;

$ymatches was never initialized. Although not strictly required by PHP, it is generally a good practice to add $ymatches = array(); before regardless.

            }
        } else {
            for ($i = $ylim - 1; $i >= $yoff; $i--) {
                $ymatches[$this->yv[$i]][] = $i;

$ymatches was never initialized. Although not strictly required by PHP, it is generally a good practice to add $ymatches = array(); before regardless.

            }
        }

        $this->lcs = 0;

The property lcs does not exist. Did you maybe forget to declare it?

        $this->seq[0] = $yoff - 1;

The property seq does not exist. Did you maybe forget to declare it?

        $this->in_seq = [];

The property in_seq does not exist. Did you maybe forget to declare it?

        $ymids[0] = [];

$ymids was never initialized. Although not strictly required by PHP, it is generally a good practice to add $ymids = array(); before regardless.

        $numer = $xlim - $xoff + $nchunks - 1;

        $x = $xoff;

        for ($chunk = 0; $chunk < $nchunks; $chunk++) {
            if ($chunk > 0) {
                for ($i = 0; $i <= $this->lcs; ++$i) {
                    $ymids[$i][$chunk - 1] = $this->seq[$i];
                }
            }

            $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $chunk) / $nchunks);

            for (; $x < $x1; $x++) {
                $line = $flip ? $this->yv[$x] : $this->xv[$x];

                if (empty($ymatches[$line])) {
                    continue;
                }

                $matches = $ymatches[$line];

                foreach ($matches as $y) {
                    if (empty($this->in_seq[$y])) {

This code seems to be duplicated across your project.

                        $k = $this->_lcsPos($y);

                        assert($k > 0);

                        $ymids[$k] = $ymids[$k - 1];

                        break;
                    }
                }

                while (list($junk, $y) = each($matches)) {

The assignment to $junk is unused. Consider omitting it like so list($first,,$third).

                    if ($y > $this->seq[$k - 1]) {
                        // assert($y < $this->seq[$k]); // GIJ Patched

                        /* Optimization: this is a common case: next match is
                         * just replacing previous match. */

                        $this->in_seq[$this->seq[$k]] = false;

The variable $k does not seem to be defined for all execution paths leading up to this point.

                        $this->seq[$k] = $y;

                        $this->in_seq[$y] = 1;
                    } elseif (empty($this->in_seq[$y])) {

This code seems to be duplicated across your project.

                        $k = $this->_lcsPos($y);

                        assert($k > 0);

                        $ymids[$k] = $ymids[$k - 1];
                    }
                }
            }
        }

        $seps[] = $flip ? [$yoff, $xoff] : [$xoff, $yoff];

$seps was never initialized. Although not strictly required by PHP, it is generally a good practice to add $seps = array(); before regardless.

        $ymid = $ymids[$this->lcs];

        for ($n = 0; $n < $nchunks - 1; $n++) {
            $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks);

            $y1 = $ymid[$n] + 1;

            $seps[] = $flip ? [$y1, $x1] : [$x1, $y1];
        }

        $seps[] = $flip ? [$ylim, $xlim] : [$xlim, $ylim];

        return [$this->lcs, $seps];
    }

    /**
     * @param $ypos
     * @return int
     */

    public function _lcsPos($ypos)
    {
        $end = $this->lcs;

        if (0 == $end || $ypos > $this->seq[$end]) {
            $this->seq[++$this->lcs] = $ypos;

            $this->in_seq[$ypos] = 1;

            return $this->lcs;
        }

        $beg = 1;

        while ($beg < $end) {
            $mid = (int)(($beg + $end) / 2);

            if ($ypos > $this->seq[$mid]) {
                $beg = $mid + 1;
            } else {
                $end = $mid;
            }
        }

        assert($ypos != $this->seq[$end]);

        $this->in_seq[$this->seq[$end]] = false;

        $this->seq[$end] = $ypos;

        $this->in_seq[$ypos] = 1;

        return $end;
    }

    /**
     * Finds LCS of two sequences.
     *
     * The results are recorded in the vectors $this->{x,y}changed[], by
     * storing a 1 in the element for each line that is an insertion or
     * deletion (ie. is not in the LCS).
     *
     * The subsequence of file 0 is (XOFF, XLIM) and likewise for file 1.
     *
     * Note that XLIM, YLIM are exclusive bounds.  All line numbers are
     * origin-0 and discarded lines are not counted.
     * @param $xoff
     * @param $xlim
     * @param $yoff
     * @param $ylim
     */

    public function _compareseq($xoff, $xlim, $yoff, $ylim)
    {
        /* Slide down the bottom initial diagonal. */

        while ($xoff < $xlim && $yoff < $ylim
               && $this->xv[$xoff] == $this->yv[$yoff]) {
            ++$xoff;

            ++$yoff;
        }

        /* Slide up the top initial diagonal. */

        while ($xlim > $xoff && $ylim > $yoff
               && $this->xv[$xlim - 1] == $this->yv[$ylim - 1]) {
            --$xlim;

            --$ylim;
        }

        if ($xoff == $xlim || $yoff == $ylim) {
            $lcs = 0;
        } else {
            /* This is ad hoc but seems to work well.  $nchunks =
             * sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5); $nchunks =
             * max(2,min(8,(int)$nchunks)); */

            $nchunks = min(7, $xlim - $xoff, $ylim - $yoff) + 1;

            list($lcs, $seps) = $this->_diag($xoff, $xlim, $yoff, $ylim, $nchunks);
        }

        if (0 == $lcs) {
            /* X and Y sequences have no common subsequence: mark all
             * changed. */

            while ($yoff < $ylim) {
                $this->ychanged[$this->yind[$yoff++]] = 1;
            }

            while ($xoff < $xlim) {
                $this->xchanged[$this->xind[$xoff++]] = 1;
            }
        } else {
            /* Use the partitions to split this problem into subproblems. */

            reset($seps);

            $pt1 = $seps[0];

            while ($pt2 = next($seps)) {
                $this->_compareseq($pt1[0], $pt2[0], $pt1[1], $pt2[1]);

                $pt1 = $pt2;
            }
        }
    }

    /**
     * Adjusts inserts/deletes of identical lines to join changes as much as
     * possible.
     *
     * We do something when a run of changed lines include a line at one end
     * and has an excluded, identical line at the other.  We are free to
     * choose which identical line is included.  `compareseq' usually chooses
     * the one at the beginning, but usually it is cleaner to consider the
     * following identical line to be the "change".
     *
     * This is extracted verbatim from analyze.c (GNU diffutils-2.7).
     * @param $lines
     * @param $other_changed
     * @param mixed $changed
     */

    public function _shiftBoundaries($lines, &$changed, $other_changed)
    {
        $i = 0;

        $j = 0;

        assert('count($lines) == count($changed)');

        $len = count($lines);

        $other_len = count($other_changed);

        while (1) {
            /* Scan forward to find the beginning of another run of
             * changes. Also keep track of the corresponding point in the
             * other file.
             *
             * Throughout this code, $i and $j are adjusted together so that
             * the first $i elements of $changed and the first $j elements of
             * $other_changed both contain the same number of zeros (unchanged
             * lines).
             *
             * Furthermore, $j is always kept so that $j == $other_len or
             * $other_changed[$j] === false. */

            while ($j < $other_len && $other_changed[$j]) {
                $j++;
            }

            while ($i < $len && !$changed[$i]) {
                assert('$j < $other_len && ! $other_changed[$j]');

                $i++;

                $j++;

                while ($j < $other_len && $other_changed[$j]) {
                    $j++;
                }
            }

            if ($i == $len) {
                break;
            }

            $start = $i;

            /* Find the end of this run of changes. */

            while (++$i < $len && $changed[$i]) {
                continue;
            }

            do {
                /* Record the length of this run of changes, so that we can
                 * later determine whether the run has grown. */

                $runlength = $i - $start;

                /* Move the changed region back, so long as the previous
                 * unchanged line matches the last changed one.  This merges
                 * with previous changed regions. */

                while ($start > 0 && $lines[$start - 1] == $lines[$i - 1]) {
                    $changed[--$start] = 1;

                    $changed[--$i] = false;

                    while ($start > 0 && $changed[$start - 1]) {
                        $start--;
                    }

                    assert('$j > 0');

                    while ($other_changed[--$j]) {
                        continue;
                    }

                    assert('$j >= 0 && !$other_changed[$j]');
                }

                /* Set CORRESPONDING to the end of the changed run, at the
                 * last point where it corresponds to a changed run in the
                 * other file. CORRESPONDING == LEN means no such point has
                 * been found. */

                $corresponding = $j < $other_len ? $i : $len;

                /* Move the changed region forward, so long as the first
                 * changed line matches the following unchanged one.  This
                 * merges with following changed regions.  Do this second, so
                 * that if there are no merges, the changed region is moved
                 * forward as far as possible. */

                while ($i < $len && $lines[$start] == $lines[$i]) {
                    $changed[$start++] = false;

                    $changed[$i++] = 1;

                    while ($i < $len && $changed[$i]) {
                        $i++;
                    }

                    assert('$j < $other_len && ! $other_changed[$j]');

                    $j++;

                    if ($j < $other_len && $other_changed[$j]) {
                        $corresponding = $i;

                        while ($j < $other_len && $other_changed[$j]) {
                            $j++;
                        }
                    }
                }
            } while ($runlength != $i - $start);

            /* If possible, move the fully-merged run of changes back to a
             * corresponding run in the other file. */

            while ($corresponding < $i) {
                $changed[--$start] = 1;

                $changed[--$i] = 0;

                assert('$j > 0');

                while ($other_changed[--$j]) {
                    continue;
                }

                assert('$j >= 0 && !$other_changed[$j]');
            }
        }
    }
}

/**
 * @package Text_Diff
 * @author  Geoffrey T. Dairiki <dairiki@dairiki.org>
 *
 * @access  private
 */
class Text_Diff_Op
{
    public $orig;

    public $final;

    public function reverse()
    {
        trigger_error('Abstract method', E_USER_ERROR);
    }

    /**
     * @return int|void
     */

    public function norig()
    {
        return $this->orig ? count($this->orig) : 0;
    }

    /**
     * @return int|void
     */

    public function nfinal()
    {
        return $this->final ? count($this->final) : 0;
    }
}

/**
 * @package Text_Diff
 * @author  Geoffrey T. Dairiki <dairiki@dairiki.org>
 *
 * @access  private
 */
class Text_Diff_Op_copy extends Text_Diff_Op
{
    /**
     * Text_Diff_Op_copy constructor.
     * @param      $orig
     * @param bool $final
     */

    public function __construct($orig, $final = false)
    {
        if (!is_array($final)) {
            $final = $orig;
        }

        $this->orig = $orig;

        $this->final = $final;
    }

    /**
     * @return \Text_Diff_Op_copy
     */

    public function &reverse()
    {
        return $reverse = new self($this->final, $this->orig);

$reverse is not used, you could remove the assignment.

    }
}

/**
 * @package Text_Diff
 * @author  Geoffrey T. Dairiki <dairiki@dairiki.org>
 *
 * @access  private
 */
class Text_Diff_Op_delete extends Text_Diff_Op

This class seems to be duplicated in your project.

{
    /**
     * Text_Diff_Op_delete constructor.
     * @param $lines
     */

    public function __construct($lines)
    {
        $this->orig = $lines;

        $this->final = false;
    }

    /**
     * @return \Text_Diff_Op_add
     */

    public function &reverse()
    {
        return $reverse = new Text_Diff_Op_add($this->orig);

$reverse is not used, you could remove the assignment.

    }
}

/**
 * @package Text_Diff
 * @author  Geoffrey T. Dairiki <dairiki@dairiki.org>
 *
 * @access  private
 */
class Text_Diff_Op_add extends Text_Diff_Op

This class seems to be duplicated in your project.

{
    /**
     * Text_Diff_Op_add constructor.
     * @param $lines
     */

    public function __construct($lines)
    {
        $this->final = $lines;

        $this->orig = false;
    }

    /**
     * @return \Text_Diff_Op_delete
     */

    public function &reverse()
    {
        return $reverse = new Text_Diff_Op_delete($this->final);

$reverse is not used, you could remove the assignment.

    }
}

/**
 * @package Text_Diff
 * @author  Geoffrey T. Dairiki <dairiki@dairiki.org>
 *
 * @access  private
 */
class Text_Diff_Op_change extends Text_Diff_Op
{
    /**
     * Text_Diff_Op_change constructor.
     * @param $orig
     * @param $final
     */

    public function __construct($orig, $final)
    {
        $this->orig = $orig;

        $this->final = $final;
    }

    /**
     * @return \Text_Diff_Op_change
     */

    public function &reverse()
    {
        return $reverse = new self($this->final, $this->orig);

$reverse is not used, you could remove the assignment.

    }
}