/phpBB/includes/diff/engine.php
PHP | 555 lines | 360 code | 70 blank | 125 comment | 103 complexity | f314246e644a57d890d5416d563a3ea2 MD5 | raw file
- <?php
- /**
- *
- * This file is part of the phpBB Forum Software package.
- *
- * @copyright (c) phpBB Limited <https://www.phpbb.com>
- * @license GNU General Public License, version 2 (GPL-2.0)
- *
- * For full copyright and license information, please see
- * the docs/CREDITS.txt file.
- *
- */
- /**
- * @ignore
- */
- if (!defined('IN_PHPBB'))
- {
- exit;
- }
- /**
- * Code from pear.php.net, Text_Diff-1.1.0 package
- * http://pear.php.net/package/Text_Diff/ (native engine)
- *
- * Modified by phpBB Limited to meet our coding standards
- * and being able to integrate into phpBB
- *
- * Class used internally by Text_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:
- * http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
- *
- * More ideas are taken from: http://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.
- *
- * Copyright 2004-2008 The Horde Project (http://www.horde.org/)
- *
- * @author Geoffrey T. Dairiki <dairiki@dairiki.org>
- * @package diff
- *
- * @access private
- */
- class diff_engine
- {
- /**
- * If set to true we trim all lines before we compare them. This ensures that sole space/tab changes do not trigger diffs.
- */
- var $skip_whitespace_changes = true;
- function diff(&$from_lines, &$to_lines, $preserve_cr = true)
- {
- // Remove empty lines...
- // If preserve_cr is true, we basically only change \r\n and bare \r to \n to get the same carriage returns for both files
- // If it is false, we try to only use \n once per line and ommit all empty lines to be able to get a proper data diff
- if (is_array($from_lines))
- {
- $from_lines = implode("\n", $from_lines);
- }
- if (is_array($to_lines))
- {
- $to_lines = implode("\n", $to_lines);
- }
- if ($preserve_cr)
- {
- $from_lines = explode("\n", str_replace("\r", "\n", str_replace("\r\n", "\n", $from_lines)));
- $to_lines = explode("\n", str_replace("\r", "\n", str_replace("\r\n", "\n", $to_lines)));
- }
- else
- {
- $from_lines = explode("\n", preg_replace('#[\n\r]+#', "\n", $from_lines));
- $to_lines = explode("\n", preg_replace('#[\n\r]+#', "\n", $to_lines));
- }
- $n_from = sizeof($from_lines);
- $n_to = sizeof($to_lines);
- $this->xchanged = $this->ychanged = $this->xv = $this->yv = $this->xind = $this->yind = array();
- unset($this->seq, $this->in_seq, $this->lcs);
- // Skip leading common lines.
- for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++)
- {
- if (trim($from_lines[$skip]) !== trim($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; $endskip++)
- {
- if (trim($from_lines[$xi]) !== trim($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; $xi++)
- {
- if ($this->skip_whitespace_changes) $xhash[trim($from_lines[$xi])] = 1; else $xhash[$from_lines[$xi]] = 1;
- }
- for ($yi = $skip; $yi < $n_to - $endskip; $yi++)
- {
- $line = ($this->skip_whitespace_changes) ? trim($to_lines[$yi]) : $to_lines[$yi];
- if (($this->ychanged[$yi] = empty($xhash[$line])))
- {
- continue;
- }
- $yhash[$line] = 1;
- $this->yv[] = $line;
- $this->yind[] = $yi;
- }
- for ($xi = $skip; $xi < $n_from - $endskip; $xi++)
- {
- $line = ($this->skip_whitespace_changes) ? trim($from_lines[$xi]) : $from_lines[$xi];
- if (($this->xchanged[$xi] = empty($yhash[$line])))
- {
- continue;
- }
- $this->xv[] = $line;
- $this->xind[] = $xi;
- }
- // Find the LCS.
- $this->_compareseq(0, sizeof($this->xv), 0, sizeof($this->yv));
- // Merge edits when possible.
- if ($this->skip_whitespace_changes)
- {
- $from_lines_clean = array_map('trim', $from_lines);
- $to_lines_clean = array_map('trim', $to_lines);
- $this->_shift_boundaries($from_lines_clean, $this->xchanged, $this->ychanged);
- $this->_shift_boundaries($to_lines_clean, $this->ychanged, $this->xchanged);
- unset($from_lines_clean, $to_lines_clean);
- }
- else
- {
- $this->_shift_boundaries($from_lines, $this->xchanged, $this->ychanged);
- $this->_shift_boundaries($to_lines, $this->ychanged, $this->xchanged);
- }
- // Compute the edit operations.
- $edits = array();
- $xi = $yi = 0;
- while ($xi < $n_from || $yi < $n_to)
- {
- // Skip matching "snake".
- $copy = array();
- while ($xi < $n_from && $yi < $n_to && !$this->xchanged[$xi] && !$this->ychanged[$yi])
- {
- $copy[] = $from_lines[$xi++];
- $yi++;
- }
- if ($copy)
- {
- $edits[] = new diff_op_copy($copy);
- }
- // Find deletes & adds.
- $delete = array();
- while ($xi < $n_from && $this->xchanged[$xi])
- {
- $delete[] = $from_lines[$xi++];
- }
- $add = array();
- while ($yi < $n_to && $this->ychanged[$yi])
- {
- $add[] = $to_lines[$yi++];
- }
- if ($delete && $add)
- {
- $edits[] = new diff_op_change($delete, $add);
- }
- else if ($delete)
- {
- $edits[] = new diff_op_delete($delete);
- }
- else if ($add)
- {
- $edits[] = new diff_op_add($add);
- }
- }
- return $edits;
- }
- /**
- * Divides the Largest Common Subsequence (LCS) of the sequences (XOFF,
- * XLIM) and (YOFF, YLIM) into NCHUNKS approximately equally sized segments.
- *
- * Returns (LCS, PTS). LCS is the length of the LCS. PTS is an array of
- * NCHUNKS+1 (X, Y) indexes giving the diving points between sub
- * sequences. The first sub-sequence is contained in (X0, X1), (Y0, Y1),
- * the second in (X1, X2), (Y1, Y2) and so on. Note that (X0, Y0) ==
- * (XOFF, YOFF) and (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM).
- *
- * This function assumes that the first lines of the specified portions of
- * the two files do not match, and likewise that the last lines do not
- * match. The caller must trim matching lines from the beginning and end
- * of the portions it is going to specify.
- */
- function _diag($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, $ylim) = array($yoff, $ylim, $xoff, $xlim);
- }
- if ($flip)
- {
- for ($i = $ylim - 1; $i >= $yoff; $i--)
- {
- $ymatches[$this->xv[$i]][] = $i;
- }
- }
- else
- {
- for ($i = $ylim - 1; $i >= $yoff; $i--)
- {
- $ymatches[$this->yv[$i]][] = $i;
- }
- }
- $this->lcs = 0;
- $this->seq[0]= $yoff - 1;
- $this->in_seq = array();
- $ymids[0] = array();
- $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];
- reset($matches);
- while (list(, $y) = each($matches))
- {
- if (empty($this->in_seq[$y]))
- {
- $k = $this->_lcs_pos($y);
- $ymids[$k] = $ymids[$k - 1];
- break;
- }
- }
- // no reset() here
- while (list(, $y) = each($matches))
- {
- if ($y > $this->seq[$k - 1])
- {
- // Optimization: this is a common case: next match is just replacing previous match.
- $this->in_seq[$this->seq[$k]] = false;
- $this->seq[$k] = $y;
- $this->in_seq[$y] = 1;
- }
- else if (empty($this->in_seq[$y]))
- {
- $k = $this->_lcs_pos($y);
- $ymids[$k] = $ymids[$k - 1];
- }
- }
- }
- }
- $seps[] = $flip ? array($yoff, $xoff) : array($xoff, $yoff);
- $ymid = $ymids[$this->lcs];
- for ($n = 0; $n < $nchunks - 1; $n++)
- {
- $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks);
- $y1 = $ymid[$n] + 1;
- $seps[] = $flip ? array($y1, $x1) : array($x1, $y1);
- }
- $seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim);
- return array($this->lcs, $seps);
- }
- function _lcs_pos($ypos)
- {
- $end = $this->lcs;
- if ($end == 0 || $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;
- }
- }
- $this->in_seq[$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 $this->{x,y}changed[], by
- * storing a 1 in the element for each line that is an insertion or
- * deletion (ie. is not in the LCS).
- *
- * The subsequence of file 0 is (XOFF, XLIM) and likewise for file 1.
- *
- * Note that XLIM, YLIM are exclusive bounds. All line numbers are
- * origin-0 and discarded lines are not counted.
- */
- function _compareseq($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, $nchunks);
- }
- if ($lcs == 0)
- {
- // 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 = $pt2;
- }
- }
- }
- /**
- * Adjusts inserts/deletes of identical lines to join changes as much as possible.
- *
- * We do something when a run of changed lines include a line at one end
- * and has an excluded, identical line at the other. We are free to
- * choose which identical line is included. 'compareseq' usually chooses
- * the one at the beginning, but usually it is cleaner to consider the
- * following identical line to be the "change".
- *
- * This is extracted verbatim from analyze.c (GNU diffutils-2.7).
- */
- function _shift_boundaries($lines, &$changed, $other_changed)
- {
- $i = 0;
- $j = 0;
- $len = sizeof($lines);
- $other_len = sizeof($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])
- {
- $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])
- {
- $start--;
- }
- while ($other_changed[--$j])
- {
- continue;
- }
- }
- // 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++;
- }
- $j++;
- if ($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;
- while ($other_changed[--$j])
- {
- continue;
- }
- }
- }
- }
- }