Text_Diff_Engine_native::_diag() - Code Metrics - Inspection of "Add circleci CI config file" - chamilo/chamilo-lms - Measure and Improve Code Quality continuously with Scrutinizer

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by Julito

created 2019-12-13 08:51 UTC

Text_Diff_Engine_native::_diag() F

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Complexity

Conditions	20
Paths	1824

Size

Total Lines	79
Code Lines	52

Duplication

Lines	0
Ratio	0 %

Importance

Changes

Metric	Value
cc	20
eloc	52
nc	1824
nop	5
dl	0
loc	79
rs	0
c	0
b	0
f	0

How to fix Long Method Complexity

<?php
/**
 * 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 <[email protected]>. The original PHP version of this
 * code was written by him, and is used/adapted with his permission.
 *
 * $Horde: framework/Text_Diff/Diff/Engine/native.php,v 1.7.2.5 2009/01/06 15:23:41 jan Exp $
 *
 * Copyright 2004-2009 The Horde Project (http://www.horde.org/)
 *
 * See the enclosed file COPYING for license information (LGPL). If you did
 * not receive this file, see http://opensource.org/licenses/lgpl-license.php.
 *
 * @author  Geoffrey T. Dairiki <[email protected]>
 * @package Text_Diff
 */
class Text_Diff_Engine_native {

    function diff($from_lines, $to_lines)
    {
        array_walk($from_lines, array('Text_Diff', 'trimNewlines'));
        array_walk($to_lines, array('Text_Diff', 'trimNewlines'));

        $n_from = count($from_lines);
        $n_to = count($to_lines);

        $this->xchanged = $this->ychanged = array();
        $this->xv = $this->yv = array();
        $this->xind = $this->yind = array();
        unset($this->seq);
        unset($this->in_seq);
        unset($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.
        $this->_compareseq(0, count($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 = array();
        $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".
            $copy = array();
            while ($xi < $n_from && $yi < $n_to
                   && !$this->xchanged[$xi] && !$this->ychanged[$yi]) {
                $copy[] = $from_lines[$xi++];
                ++$yi;
            }
            if ($copy) {
                $edits[] = new Text_Diff_Op_copy($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) {
                $edits[] = new Text_Diff_Op_change($delete, $add);
            } elseif ($delete) {
                $edits[] = new Text_Diff_Op_delete($delete);
            } elseif ($add) {
                $edits[] = new Text_Diff_Op_add($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.
     */
    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 = $this->_lcsPos($y);
                        assert($k > 0);
                        $ymids[$k] = $ymids[$k - 1];
                        break;
                    }
                }
                while (list(, $y) = each($matches)) {
                    if ($y > $this->seq[$k - 1]) {
                        assert($y <= $this->seq[$k]);
                        /* 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;
                    } elseif (empty($this->in_seq[$y])) {
                        $k = $this->_lcsPos($y);
                        assert($k > 0);
                        $ymids[$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 _lcsPos($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;
            }
        }

        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 $this->{x,y}changed[], by
     * storing a 1 in the element for each line that is an insertion or
     * deletion (ie. is not in the LCS).
     *
     * The subsequence of file 0 is (XOFF, XLIM) and likewise for file 1.
     *
     * Note that XLIM, YLIM are exclusive bounds.  All line numbers are
     * origin-0 and discarded lines are not counted.
     */
    function _compareseq ($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 _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]');
            }
        }
    }

}


1			<?php
2			/**
3			* Class used internally by Text_Diff to actually compute the diffs.
4			*
5			* This class is implemented using native PHP code.
6			*
7			* The algorithm used here is mostly lifted from the perl module
8			* Algorithm::Diff (version 1.06) by Ned Konz, which is available at:
9			* http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
10			*
11			* More ideas are taken from: http://www.ics.uci.edu/~eppstein/161/960229.html
12			*
13			* Some ideas (and a bit of code) are taken from analyze.c, of GNU
14			* diffutils-2.7, which can be found at:
15			* ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz
16			*
17			* Some ideas (subdivision by NCHUNKS > 2, and some optimizations) are from
18			* Geoffrey T. Dairiki <[email protected]>. The original PHP version of this
19			* code was written by him, and is used/adapted with his permission.
20			*
21			* $Horde: framework/Text_Diff/Diff/Engine/native.php,v 1.7.2.5 2009/01/06 15:23:41 jan Exp $
22			*
23			* Copyright 2004-2009 The Horde Project (http://www.horde.org/)
24			*
25			* See the enclosed file COPYING for license information (LGPL). If you did
26			* not receive this file, see http://opensource.org/licenses/lgpl-license.php.
27			*
28			* @author Geoffrey T. Dairiki <[email protected]>
29			* @package Text_Diff
30			*/
31			class Text_Diff_Engine_native {
32
33			function diff($from_lines, $to_lines)
34			{
35			array_walk($from_lines, array('Text_Diff', 'trimNewlines'));
36			array_walk($to_lines, array('Text_Diff', 'trimNewlines'));
37
38			$n_from = count($from_lines);
39			$n_to = count($to_lines);
40
41			$this->xchanged = $this->ychanged = array();
42			$this->xv = $this->yv = array();
43			$this->xind = $this->yind = array();
44			unset($this->seq);
45			unset($this->in_seq);
46			unset($this->lcs);
47
48			// Skip leading common lines.
49			for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++) {
50			if ($from_lines[$skip] !== $to_lines[$skip]) {
51			break;
52			}
53			$this->xchanged[$skip] = $this->ychanged[$skip] = false;
54			}
55
56			// Skip trailing common lines.
57			$xi = $n_from; $yi = $n_to;
58			for ($endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++) {
59			if ($from_lines[$xi] !== $to_lines[$yi]) {
60			break;
61			}
62			$this->xchanged[$xi] = $this->ychanged[$yi] = false;
63			}
64
65			// Ignore lines which do not exist in both files.
66			for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
67			$xhash[$from_lines[$xi]] = 1;
68			}
69			for ($yi = $skip; $yi < $n_to - $endskip; $yi++) {
70			$line = $to_lines[$yi];
71			if (($this->ychanged[$yi] = empty($xhash[$line]))) {
72			continue;
73			}
74			$yhash[$line] = 1;
75			$this->yv[] = $line;
76			$this->yind[] = $yi;
77			}
78			for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
79			$line = $from_lines[$xi];
80			if (($this->xchanged[$xi] = empty($yhash[$line]))) {
81			continue;
82			}
83			$this->xv[] = $line;
84			$this->xind[] = $xi;
85			}
86
87			// Find the LCS.
88			$this->_compareseq(0, count($this->xv), 0, count($this->yv));
89
90			// Merge edits when possible.
91			$this->_shiftBoundaries($from_lines, $this->xchanged, $this->ychanged);
92			$this->_shiftBoundaries($to_lines, $this->ychanged, $this->xchanged);
93
94			// Compute the edit operations.
95			$edits = array();
96			$xi = $yi = 0;
97			while ($xi < $n_from \|\| $yi < $n_to) {
98			assert($yi < $n_to \|\| $this->xchanged[$xi]);
99			assert($xi < $n_from \|\| $this->ychanged[$yi]);
100
101			// Skip matching "snake".
102			$copy = array();
103			while ($xi < $n_from && $yi < $n_to
104			&& !$this->xchanged[$xi] && !$this->ychanged[$yi]) {
105			$copy[] = $from_lines[$xi++];
106			++$yi;
107			}
108			if ($copy) {
109			$edits[] = new Text_Diff_Op_copy($copy);
110			}
111
112			// Find deletes & adds.
113			$delete = array();
114			while ($xi < $n_from && $this->xchanged[$xi]) {
115			$delete[] = $from_lines[$xi++];
116			}
117
118			$add = array();
119			while ($yi < $n_to && $this->ychanged[$yi]) {
120			$add[] = $to_lines[$yi++];
121			}
122
123			if ($delete && $add) {
124			$edits[] = new Text_Diff_Op_change($delete, $add);
125			} elseif ($delete) {
126			$edits[] = new Text_Diff_Op_delete($delete);
127			} elseif ($add) {
128			$edits[] = new Text_Diff_Op_add($add);
129			}
130			}
131
132			return $edits;
133			}
134
135			/**
136			* Divides the Largest Common Subsequence (LCS) of the sequences (XOFF,
137			* XLIM) and (YOFF, YLIM) into NCHUNKS approximately equally sized
138			* segments.
139			*
140			* Returns (LCS, PTS). LCS is the length of the LCS. PTS is an array of
141			* NCHUNKS+1 (X, Y) indexes giving the diving points between sub
142			* sequences. The first sub-sequence is contained in (X0, X1), (Y0, Y1),
143			* the second in (X1, X2), (Y1, Y2) and so on. Note that (X0, Y0) ==
144			* (XOFF, YOFF) and (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM).
145			*
146			* This function assumes that the first lines of the specified portions of
147			* the two files do not match, and likewise that the last lines do not
148			* match. The caller must trim matching lines from the beginning and end
149			* of the portions it is going to specify.
150			*/
151			function _diag ($xoff, $xlim, $yoff, $ylim, $nchunks)
152			{
153			$flip = false;
154
155			if ($xlim - $xoff > $ylim - $yoff) {
156			/* Things seems faster (I'm not sure I understand why) when the
157			* shortest sequence is in X. */
158			$flip = true;
159			list ($xoff, $xlim, $yoff, $ylim)
160			= array($yoff, $ylim, $xoff, $xlim);
161			}
162
163			if ($flip) {
164			for ($i = $ylim - 1; $i >= $yoff; $i--) {
165			$ymatches[$this->xv[$i]][] = $i;
166			}
167			} else {
168			for ($i = $ylim - 1; $i >= $yoff; $i--) {
169			$ymatches[$this->yv[$i]][] = $i;
170			}
171			}
172
173			$this->lcs = 0;
174			$this->seq[0]= $yoff - 1;
175			$this->in_seq = array();
176			$ymids[0] = array();
177
178			$numer = $xlim - $xoff + $nchunks - 1;
179			$x = $xoff;
180			for ($chunk = 0; $chunk < $nchunks; $chunk++) {
181			if ($chunk > 0) {
182			for ($i = 0; $i <= $this->lcs; $i++) {
183			$ymids[$i][$chunk - 1] = $this->seq[$i];
184			}
185			}
186
187			$x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $chunk) / $nchunks);
188			for (; $x < $x1; $x++) {
189			$line = $flip ? $this->yv[$x] : $this->xv[$x];
190			if (empty($ymatches[$line])) {
191			continue;
192			}
193			$matches = $ymatches[$line];
194			reset($matches);
195			while (list(, $y) = each($matches)) {
196			if (empty($this->in_seq[$y])) {
197			$k = $this->_lcsPos($y);
198			assert($k > 0);
199			$ymids[$k] = $ymids[$k - 1];
200			break;
201			}
202			}
203			while (list(, $y) = each($matches)) {
204			if ($y > $this->seq[$k - 1]) {
205			assert($y <= $this->seq[$k]);
206			/* Optimization: this is a common case: next match is
207			* just replacing previous match. */
208			$this->in_seq[$this->seq[$k]] = false;
209			$this->seq[$k] = $y;
210			$this->in_seq[$y] = 1;
211			} elseif (empty($this->in_seq[$y])) {
212			$k = $this->_lcsPos($y);
213			assert($k > 0);
214			$ymids[$k] = $ymids[$k - 1];
215			}
216			}
217			}
218			}
219
220			$seps[] = $flip ? array($yoff, $xoff) : array($xoff, $yoff);
221			$ymid = $ymids[$this->lcs];
222			for ($n = 0; $n < $nchunks - 1; $n++) {
223			$x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks);
224			$y1 = $ymid[$n] + 1;
225			$seps[] = $flip ? array($y1, $x1) : array($x1, $y1);
226			}
227			$seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim);
228
229			return array($this->lcs, $seps);
230			}
231
232			function _lcsPos($ypos)
233			{
234			$end = $this->lcs;
235			if ($end == 0 \|\| $ypos > $this->seq[$end]) {
236			$this->seq[++$this->lcs] = $ypos;
237			$this->in_seq[$ypos] = 1;
238			return $this->lcs;
239			}
240
241			$beg = 1;
242			while ($beg < $end) {
243			$mid = (int)(($beg + $end) / 2);
244			if ($ypos > $this->seq[$mid]) {
245			$beg = $mid + 1;
246			} else {
247			$end = $mid;
248			}
249			}
250
251			assert($ypos != $this->seq[$end]);
252
253			$this->in_seq[$this->seq[$end]] = false;
254			$this->seq[$end] = $ypos;
255			$this->in_seq[$ypos] = 1;
256			return $end;
257			}
258
259			/**
260			* Finds LCS of two sequences.
261			*
262			* The results are recorded in the vectors $this->{x,y}changed[], by
263			* storing a 1 in the element for each line that is an insertion or
264			* deletion (ie. is not in the LCS).
265			*
266			* The subsequence of file 0 is (XOFF, XLIM) and likewise for file 1.
267			*
268			* Note that XLIM, YLIM are exclusive bounds. All line numbers are
269			* origin-0 and discarded lines are not counted.
270			*/
271			function _compareseq ($xoff, $xlim, $yoff, $ylim)
272			{
273			/* Slide down the bottom initial diagonal. */
274			while ($xoff < $xlim && $yoff < $ylim
275			&& $this->xv[$xoff] == $this->yv[$yoff]) {
276			++$xoff;
277			++$yoff;
278			}
279
280			/* Slide up the top initial diagonal. */
281			while ($xlim > $xoff && $ylim > $yoff
282			&& $this->xv[$xlim - 1] == $this->yv[$ylim - 1]) {
283			--$xlim;
284			--$ylim;
285			}
286
287			if ($xoff == $xlim \|\| $yoff == $ylim) {
288			$lcs = 0;
289			} else {
290			/* This is ad hoc but seems to work well. $nchunks =
291			* sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5); $nchunks =
292			* max(2,min(8,(int)$nchunks)); */
293			$nchunks = min(7, $xlim - $xoff, $ylim - $yoff) + 1;
294			list($lcs, $seps)
295			= $this->_diag($xoff, $xlim, $yoff, $ylim, $nchunks);
296			}
297
298			if ($lcs == 0) {
299			/* X and Y sequences have no common subsequence: mark all
300			* changed. */
301			while ($yoff < $ylim) {
302			$this->ychanged[$this->yind[$yoff++]] = 1;
303			}
304			while ($xoff < $xlim) {
305			$this->xchanged[$this->xind[$xoff++]] = 1;
306			}
307			} else {
308			/* Use the partitions to split this problem into subproblems. */
309			reset($seps);
310			$pt1 = $seps[0];
311			while ($pt2 = next($seps)) {
312			$this->_compareseq ($pt1[0], $pt2[0], $pt1[1], $pt2[1]);
313			$pt1 = $pt2;
314			}
315			}
316			}
317
318			/**
319			* Adjusts inserts/deletes of identical lines to join changes as much as
320			* possible.
321			*
322			* We do something when a run of changed lines include a line at one end
323			* and has an excluded, identical line at the other. We are free to
324			* choose which identical line is included. `compareseq' usually chooses
325			* the one at the beginning, but usually it is cleaner to consider the
326			* following identical line to be the "change".
327			*
328			* This is extracted verbatim from analyze.c (GNU diffutils-2.7).
329			*/
330			function _shiftBoundaries($lines, &$changed, $other_changed)
331			{
332			$i = 0;
333			$j = 0;
334
335			assert('count($lines) == count($changed)');
336			$len = count($lines);
337			$other_len = count($other_changed);
338
339			while (1) {
340			/* Scan forward to find the beginning of another run of
341			* changes. Also keep track of the corresponding point in the
342			* other file.
343			*
344			* Throughout this code, $i and $j are adjusted together so that
345			* the first $i elements of $changed and the first $j elements of
346			* $other_changed both contain the same number of zeros (unchanged
347			* lines).
348			*
349			* Furthermore, $j is always kept so that $j == $other_len or
350			* $other_changed[$j] == false. */
351			while ($j < $other_len && $other_changed[$j]) {
352			$j++;
353			}
354
355			while ($i < $len && ! $changed[$i]) {
356			assert('$j < $other_len && ! $other_changed[$j]');
357			$i++; $j++;
358			while ($j < $other_len && $other_changed[$j]) {
359			$j++;
360			}
361			}
362
363			if ($i == $len) {
364			break;
365			}
366
367			$start = $i;
368
369			/* Find the end of this run of changes. */
370			while (++$i < $len && $changed[$i]) {
371			continue;
372			}
373
374			do {
375			/* Record the length of this run of changes, so that we can
376			* later determine whether the run has grown. */
377			$runlength = $i - $start;
378
379			/* Move the changed region back, so long as the previous
380			* unchanged line matches the last changed one. This merges
381			* with previous changed regions. */
382			while ($start > 0 && $lines[$start - 1] == $lines[$i - 1]) {
383			$changed[--$start] = 1;
384			$changed[--$i] = false;
385			while ($start > 0 && $changed[$start - 1]) {
386			$start--;
387			}
388			assert('$j > 0');
389			while ($other_changed[--$j]) {
390			continue;
391			}
392			assert('$j >= 0 && !$other_changed[$j]');
393			}
394
395			/* Set CORRESPONDING to the end of the changed run, at the
396			* last point where it corresponds to a changed run in the
397			* other file. CORRESPONDING == LEN means no such point has
398			* been found. */
399			$corresponding = $j < $other_len ? $i : $len;
400
401			/* Move the changed region forward, so long as the first
402			* changed line matches the following unchanged one. This
403			* merges with following changed regions. Do this second, so
404			* that if there are no merges, the changed region is moved
405			* forward as far as possible. */
406			while ($i < $len && $lines[$start] == $lines[$i]) {
407			$changed[$start++] = false;
408			$changed[$i++] = 1;
409			while ($i < $len && $changed[$i]) {
410			$i++;
411			}
412
413			assert('$j < $other_len && ! $other_changed[$j]');
414			$j++;
415			if ($j < $other_len && $other_changed[$j]) {
416			$corresponding = $i;
417			while ($j < $other_len && $other_changed[$j]) {
418			$j++;
419			}
420			}
421			}
422			} while ($runlength != $i - $start);
423
424			/* If possible, move the fully-merged run of changes back to a
425			* corresponding run in the other file. */
426			while ($corresponding < $i) {
427			$changed[--$start] = 1;
428			$changed[--$i] = 0;
429			assert('$j > 0');
430			while ($other_changed[--$j]) {
431			continue;
432			}
433			assert('$j >= 0 && !$other_changed[$j]');
434			}
435			}
436			}
437
438			}
439

chamilo / chamilo-lms

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Text_Diff_Engine_native::_diag() F

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