~azzar1/unity/add-show-desktop-key : contents of www/php/phpBB3/includes/diff/engine.php at revision 1080.1.16

~azzar1/unity/add-show-desktop-key : (revision 1080.1.16)

<?php
/**
*
* @package diff
* @version $Id: engine.php,v 1.7 2007/10/05 14:36:33 acydburn Exp $
* @copyright (c) 2006 phpBB Group
* @license http://opensource.org/licenses/gpl-license.php GNU Public License
*
*/

/**
* @ignore
*/
if (!defined('IN_PHPBB'))
{
	exit;
}

/**
* Code from pear.php.net, Text_Diff-0.2.1 (beta) package
* http://pear.php.net/package/Text_Diff/
*
* Modified by phpBB Group to meet our coding standards
* and being able to integrate into phpBB
*
* 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:
* 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.
*
* @author  Geoffrey T. Dairiki <dairiki@dairiki.org>
* @package diff
*
* @access private
*/
class diff_engine
{
	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; $skip++)
		{
			if ($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;
		}

		for ($yi = $skip; $yi < $n_to - $endskip; $yi++)
		{
			$line = $to_lines[$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 = $from_lines[$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.
		$this->_shift_boundaries($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];

				foreach ($matches as $y)
				{
					if (empty($this->in_seq[$y]))
					{
						$k = $this->_lcs_pos($y);
						$ymids[$k] = $ymids[$k - 1];
						break;
					}
				}

				// no reset() here
				while (list($junk, $y) = each($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;
				}
			}
		}
	}
}

?>

443 by dcoles Added Forum application along with unmodifed version of phpBB3 "Olympus" 3.0.0	1	<?php
	2	/**
	3	*
	4	* @package diff
	5	* @version $Id: engine.php,v 1.7 2007/10/05 14:36:33 acydburn Exp $
	6	* @copyright (c) 2006 phpBB Group
	7	* @license http://opensource.org/licenses/gpl-license.php GNU Public License
	8	*
	9	*/
	10
	11	/**
	12	* @ignore
	13	*/
	14	if (!defined('IN_PHPBB'))
	15	{
	16	exit;
	17	}
	18
	19	/**
	20	* Code from pear.php.net, Text_Diff-0.2.1 (beta) package
	21	* http://pear.php.net/package/Text_Diff/
	22	*
	23	* Modified by phpBB Group to meet our coding standards
	24	* and being able to integrate into phpBB
	25	*
	26	* Class used internally by Diff to actually compute the diffs. This class is
	27	* implemented using native PHP code.
	28	*
	29	* The algorithm used here is mostly lifted from the perl module
	30	* Algorithm::Diff (version 1.06) by Ned Konz, which is available at:
	31	* http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
	32	*
	33	* More ideas are taken from:
	34	* http://www.ics.uci.edu/~eppstein/161/960229.html
	35	*
	36	* Some ideas (and a bit of code) are taken from analyze.c, of GNU
	37	* diffutils-2.7, which can be found at:
	38	* ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz
	39	*
	40	* Some ideas (subdivision by NCHUNKS > 2, and some optimizations) are from
	41	* Geoffrey T. Dairiki <dairiki@dairiki.org>. The original PHP version of this
	42	* code was written by him, and is used/adapted with his permission.
	43	*
	44	* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
	45	* @package diff
	46	*
	47	* @access private
	48	*/
	49	class diff_engine
	50	{
	51	function diff(&$from_lines, &$to_lines, $preserve_cr = true)
	52	{
	53	// Remove empty lines...
	54	// If preserve_cr is true, we basically only change \r\n and bare \r to \n to get the same carriage returns for both files
	55	// If it is false, we try to only use \n once per line and ommit all empty lines to be able to get a proper data diff
	56
	57	if (is_array($from_lines))
	58	{
	59	$from_lines = implode("\n", $from_lines);
	60	}
	61
	62	if (is_array($to_lines))
	63	{
	64	$to_lines = implode("\n", $to_lines);
65	}
66
67	if ($preserve_cr)
68	{
69	$from_lines = explode("\n", str_replace("\r", "\n", str_replace("\r\n", "\n", $from_lines)));
70	$to_lines = explode("\n", str_replace("\r", "\n", str_replace("\r\n", "\n", $to_lines)));
71	}
72	else
73	{
74	$from_lines = explode("\n", preg_replace('#[\n\r]+#', "\n", $from_lines));
75	$to_lines = explode("\n", preg_replace('#[\n\r]+#', "\n", $to_lines));
76	}
77
78	$n_from = sizeof($from_lines);
79	$n_to = sizeof($to_lines);
80
81	$this->xchanged = $this->ychanged = $this->xv = $this->yv = $this->xind = $this->yind = array();
82	unset($this->seq, $this->in_seq, $this->lcs);
83
84	// Skip leading common lines.
85	for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++)
86	{
87	if ($from_lines[$skip] !== $to_lines[$skip])
88	{
89	break;
90	}
91	$this->xchanged[$skip] = $this->ychanged[$skip] = false;
92	}
93
94	// Skip trailing common lines.
95	$xi = $n_from;
96	$yi = $n_to;
97
98	for ($endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++)
99	{
100	if ($from_lines[$xi] !== $to_lines[$yi])
101	{
102	break;
103	}
104	$this->xchanged[$xi] = $this->ychanged[$yi] = false;
105	}
106
107	// Ignore lines which do not exist in both files.
108	for ($xi = $skip; $xi < $n_from - $endskip; $xi++)
109	{
110	$xhash[$from_lines[$xi]] = 1;
111	}
112
113	for ($yi = $skip; $yi < $n_to - $endskip; $yi++)
114	{
115	$line = $to_lines[$yi];
116
117	if (($this->ychanged[$yi] = empty($xhash[$line])))
118	{
119	continue;
120	}
121	$yhash[$line] = 1;
122	$this->yv[] = $line;
123	$this->yind[] = $yi;
124	}
125
126	for ($xi = $skip; $xi < $n_from - $endskip; $xi++)
127	{
128	$line = $from_lines[$xi];
129
130	if (($this->xchanged[$xi] = empty($yhash[$line])))
131	{
132	continue;
133	}
134	$this->xv[] = $line;
135	$this->xind[] = $xi;
136	}
137
138	// Find the LCS.
139	$this->_compareseq(0, sizeof($this->xv), 0, sizeof($this->yv));
140
141	// Merge edits when possible.
142	$this->_shift_boundaries($from_lines, $this->xchanged, $this->ychanged);
143	$this->_shift_boundaries($to_lines, $this->ychanged, $this->xchanged);
144
145	// Compute the edit operations.
146	$edits = array();
147	$xi = $yi = 0;
148
149	while ($xi < $n_from \|\| $yi < $n_to)
150	{
151	// Skip matching "snake".
152	$copy = array();
153
154	while ($xi < $n_from && $yi < $n_to && !$this->xchanged[$xi] && !$this->ychanged[$yi])
155	{
156	$copy[] = $from_lines[$xi++];
157	$yi++;
158	}
159
160	if ($copy)
161	{
162	$edits[] = &new diff_op_copy($copy);
163	}
164
165	// Find deletes & adds.
166	$delete = array();
167	while ($xi < $n_from && $this->xchanged[$xi])
168	{
169	$delete[] = $from_lines[$xi++];
170	}
171
172	$add = array();
173	while ($yi < $n_to && $this->ychanged[$yi])
174	{
175	$add[] = $to_lines[$yi++];
176	}
177
178	if ($delete && $add)
179	{
180	$edits[] = &new diff_op_change($delete, $add);
181	}
182	else if ($delete)
183	{
184	$edits[] = &new diff_op_delete($delete);
185	}
186	else if ($add)
187	{
188	$edits[] = &new diff_op_add($add);
189	}
190	}
191
192	return $edits;
193	}
194
195	/**
196	* Divides the Largest Common Subsequence (LCS) of the sequences (XOFF,
197	* XLIM) and (YOFF, YLIM) into NCHUNKS approximately equally sized segments.
198	*
199	* Returns (LCS, PTS). LCS is the length of the LCS. PTS is an array of
200	* NCHUNKS+1 (X, Y) indexes giving the diving points between sub
201	* sequences. The first sub-sequence is contained in (X0, X1), (Y0, Y1),
202	* the second in (X1, X2), (Y1, Y2) and so on. Note that (X0, Y0) ==
203	* (XOFF, YOFF) and (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM).
204	*
205	* This function assumes that the first lines of the specified portions of
206	* the two files do not match, and likewise that the last lines do not
207	* match. The caller must trim matching lines from the beginning and end
208	* of the portions it is going to specify.
209	*/
210	function _diag($xoff, $xlim, $yoff, $ylim, $nchunks)
211	{
212	$flip = false;
213
214	if ($xlim - $xoff > $ylim - $yoff)
215	{
216	// Things seems faster (I'm not sure I understand why) when the shortest sequence is in X.
217	$flip = true;
218	list($xoff, $xlim, $yoff, $ylim) = array($yoff, $ylim, $xoff, $xlim);
219	}
220
221	if ($flip)
222	{
223	for ($i = $ylim - 1; $i >= $yoff; $i--)
224	{
225	$ymatches[$this->xv[$i]][] = $i;
226	}
227	}
228	else
229	{
230	for ($i = $ylim - 1; $i >= $yoff; $i--)
231	{
232	$ymatches[$this->yv[$i]][] = $i;
233	}
234	}
235
236	$this->lcs = 0;
237	$this->seq[0]= $yoff - 1;
238	$this->in_seq = array();
239	$ymids[0] = array();
240
241	$numer = $xlim - $xoff + $nchunks - 1;
242	$x = $xoff;
243
244	for ($chunk = 0; $chunk < $nchunks; $chunk++)
245	{
246	if ($chunk > 0)
247	{
248	for ($i = 0; $i <= $this->lcs; $i++)
249	{
250	$ymids[$i][$chunk - 1] = $this->seq[$i];
251	}
252	}
253
254	$x1 = $xoff + (int)(($numer + ($xlim-$xoff)*$chunk) / $nchunks);
255
256	for (; $x < $x1; $x++)
257	{
258	$line = $flip ? $this->yv[$x] : $this->xv[$x];
259	if (empty($ymatches[$line]))
260	{
261	continue;
262	}
263	$matches = $ymatches[$line];
264
265	foreach ($matches as $y)
266	{
267	if (empty($this->in_seq[$y]))
268	{
269	$k = $this->_lcs_pos($y);
270	$ymids[$k] = $ymids[$k - 1];
271	break;
272	}
273	}
274
275	// no reset() here
276	while (list($junk, $y) = each($matches))
277	{
278	if ($y > $this->seq[$k - 1])
279	{
280	// Optimization: this is a common case: next match is just replacing previous match.
281	$this->in_seq[$this->seq[$k]] = false;
282	$this->seq[$k] = $y;
283	$this->in_seq[$y] = 1;
284	}
285	else if (empty($this->in_seq[$y]))
286	{
287	$k = $this->_lcs_pos($y);
288	$ymids[$k] = $ymids[$k - 1];
289	}
290	}
291	}
292	}
293
294	$seps[] = $flip ? array($yoff, $xoff) : array($xoff, $yoff);
295	$ymid = $ymids[$this->lcs];
296
297	for ($n = 0; $n < $nchunks - 1; $n++)
298	{
299	$x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks);
300	$y1 = $ymid[$n] + 1;
301	$seps[] = $flip ? array($y1, $x1) : array($x1, $y1);
302	}
303	$seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim);
304
305	return array($this->lcs, $seps);
306	}
307
308	function _lcs_pos($ypos)
309	{
310	$end = $this->lcs;
311
312	if ($end == 0 \|\| $ypos > $this->seq[$end])
313	{
314	$this->seq[++$this->lcs] = $ypos;
315	$this->in_seq[$ypos] = 1;
316	return $this->lcs;
317	}
318
319	$beg = 1;
320	while ($beg < $end)
321	{
322	$mid = (int)(($beg + $end) / 2);
323	if ($ypos > $this->seq[$mid])
324	{
325	$beg = $mid + 1;
326	}
327	else
328	{
329	$end = $mid;
330	}
331	}
332
333	$this->in_seq[$this->seq[$end]] = false;
334	$this->seq[$end] = $ypos;
335	$this->in_seq[$ypos] = 1;
336
337	return $end;
338	}
339
340	/**
341	* Finds LCS of two sequences.
342	*
343	* The results are recorded in the vectors $this->{x,y}changed[], by
344	* storing a 1 in the element for each line that is an insertion or
345	* deletion (ie. is not in the LCS).
346	*
347	* The subsequence of file 0 is (XOFF, XLIM) and likewise for file 1.
348	*
349	* Note that XLIM, YLIM are exclusive bounds. All line numbers are
350	* origin-0 and discarded lines are not counted.
351	*/
352	function _compareseq($xoff, $xlim, $yoff, $ylim)
353	{
354	// Slide down the bottom initial diagonal.
355	while ($xoff < $xlim && $yoff < $ylim && $this->xv[$xoff] == $this->yv[$yoff])
356	{
357	++$xoff;
358	++$yoff;
359	}
360
361	// Slide up the top initial diagonal.
362	while ($xlim > $xoff && $ylim > $yoff && $this->xv[$xlim - 1] == $this->yv[$ylim - 1])
363	{
364	--$xlim;
365	--$ylim;
366	}
367
368	if ($xoff == $xlim \|\| $yoff == $ylim)
369	{
370	$lcs = 0;
371	}
372	else
373	{
374	// This is ad hoc but seems to work well.
375	// $nchunks = sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5);
376	// $nchunks = max(2,min(8,(int)$nchunks));
377	$nchunks = min(7, $xlim - $xoff, $ylim - $yoff) + 1;
378	list($lcs, $seps) = $this->_diag($xoff, $xlim, $yoff, $ylim, $nchunks);
379	}
380
381	if ($lcs == 0)
382	{
383	// X and Y sequences have no common subsequence: mark all changed.
384	while ($yoff < $ylim)
385	{
386	$this->ychanged[$this->yind[$yoff++]] = 1;
387	}
388
389	while ($xoff < $xlim)
390	{
391	$this->xchanged[$this->xind[$xoff++]] = 1;
392	}
393	}
394	else
395	{
396	// Use the partitions to split this problem into subproblems.
397	reset($seps);
398	$pt1 = $seps[0];
399
400	while ($pt2 = next($seps))
401	{
402	$this->_compareseq($pt1[0], $pt2[0], $pt1[1], $pt2[1]);
403	$pt1 = $pt2;
404	}
405	}
406	}
407
408	/**
409	* Adjusts inserts/deletes of identical lines to join changes as much as possible.
410	*
411	* We do something when a run of changed lines include a line at one end
412	* and has an excluded, identical line at the other. We are free to
413	* choose which identical line is included. 'compareseq' usually chooses
414	* the one at the beginning, but usually it is cleaner to consider the
415	* following identical line to be the "change".
416	*
417	* This is extracted verbatim from analyze.c (GNU diffutils-2.7).
418	*/
419	function _shift_boundaries($lines, &$changed, $other_changed)
420	{
421	$i = 0;
422	$j = 0;
423
424	$len = sizeof($lines);
425	$other_len = sizeof($other_changed);
426
427	while (1)
428	{
429	// Scan forward to find the beginning of another run of
430	// changes. Also keep track of the corresponding point in the other file.
431	//
432	// Throughout this code, $i and $j are adjusted together so that
433	// the first $i elements of $changed and the first $j elements of
434	// $other_changed both contain the same number of zeros (unchanged lines).
435	//
436	// Furthermore, $j is always kept so that $j == $other_len or $other_changed[$j] == false.
437	while ($j < $other_len && $other_changed[$j])
438	{
439	$j++;
440	}
441
442	while ($i < $len && ! $changed[$i])
443	{
444	$i++;
445	$j++;
446
447	while ($j < $other_len && $other_changed[$j])
448	{
449	$j++;
450	}
451	}
452
453	if ($i == $len)
454	{
455	break;
456	}
457
458	$start = $i;
459
460	// Find the end of this run of changes.
461	while (++$i < $len && $changed[$i])
462	{
463	continue;
464	}
465
466	do
467	{
468	// Record the length of this run of changes, so that we can later determine whether the run has grown.
469	$runlength = $i - $start;
470
471	// Move the changed region back, so long as the previous unchanged line matches the last changed one.
472	// This merges with previous changed regions.
473	while ($start > 0 && $lines[$start - 1] == $lines[$i - 1])
474	{
475	$changed[--$start] = 1;
476	$changed[--$i] = false;
477
478	while ($start > 0 && $changed[$start - 1])
479	{
480	$start--;
481	}
482
483	while ($other_changed[--$j])
484	{
485	continue;
486	}
487	}
488
489	// Set CORRESPONDING to the end of the changed run, at the last point where it corresponds to a changed run in the
490	// other file. CORRESPONDING == LEN means no such point has been found.
491	$corresponding = $j < $other_len ? $i : $len;
492
493	// Move the changed region forward, so long as the first changed line matches the following unchanged one.
494	// This merges with following changed regions.
495	// Do this second, so that if there are no merges, the changed region is moved forward as far as possible.
496	while ($i < $len && $lines[$start] == $lines[$i])
497	{
498	$changed[$start++] = false;
499	$changed[$i++] = 1;
500
501	while ($i < $len && $changed[$i])
502	{
503	$i++;
504	}
505
506	$j++;
507	if ($j < $other_len && $other_changed[$j])
508	{
509	$corresponding = $i;
510	while ($j < $other_len && $other_changed[$j])
511	{
512	$j++;
513	}
514	}
515	}
516	}
517	while ($runlength != $i - $start);
518
519	// If possible, move the fully-merged run of changes back to a corresponding run in the other file.
520	while ($corresponding < $i)
521	{
522	$changed[--$start] = 1;
523	$changed[--$i] = 0;
524
525	while ($other_changed[--$j])
526	{
527	continue;
528	}
529	}
530	}
531	}
532	}
533
534	?>