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Public Member Functions | Data Fields
_DiffEngine Class Reference
+ Collaboration diagram for _DiffEngine:

Public Member Functions

 diff ($from_lines, $to_lines)
 _line_hash ($line)
 Returns the whole line if it's small enough, or the MD5 hash otherwise.
 _diag ($xoff, $xlim, $yoff, $ylim, $nchunks)
 _lcs_pos ($ypos)
 _compareseq ($xoff, $xlim, $yoff, $ylim)
 _shift_boundaries ($lines, &$changed, $other_changed)

Data Fields

const MAX_XREF_LENGTH = 10000

Detailed Description

Definition at line 767 of file class.WordLevelDiff.php.

Member Function Documentation

_DiffEngine::_compareseq (   $xoff,
  $xlim,
  $yoff,
  $ylim 
)

Definition at line 1011 of file class.WordLevelDiff.php.

{
$fname = '_DiffEngine::_compareseq';
//wfProfileIn( $fname );
// Slide down the bottom initial diagonal.
while ($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)
_DiffEngine::_diag (   $xoff,
  $xlim,
  $yoff,
  $ylim,
  $nchunks 
)

Definition at line 892 of file class.WordLevelDiff.php.

References _lcs_pos(), and USE_ASSERTS.

{
$fname = '_DiffEngine::_diag';
//wfProfileIn( $fname );
$flip = false;
if ($xlim - $xoff > $ylim - $yoff) {
// Things seems faster (I'm not sure I understand why)
// when the shortest sequence 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; $chunk++) {
//wfProfileIn( "$fname-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($matches);
while (list ($junk, $y) = each($matches))
if (empty($this->in_seq[$y])) {
$k = $this->_lcs_pos($y);
USE_ASSERTS && assert($k > 0);
$ymids[$k] = $ymids[$k-1];
break;
}
while (list ( /* $junk */, $y) = each($matches)) {
if ($y > $this->seq[$k-1]) {
USE_ASSERTS && 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;
} else if (empty($this->in_seq[$y])) {
$k = $this->_lcs_pos($y);
USE_ASSERTS && assert($k > 0);
$ymids[$k] = $ymids[$k-1];
}
}
}
//wfProfileOut( "$fname-chunk" );

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_DiffEngine::_lcs_pos (   $ypos)

Definition at line 970 of file class.WordLevelDiff.php.

References $n.

Referenced by _diag().

: 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);
//wfProfileOut( $fname );
return array($this->lcs, $seps);
}
function _lcs_pos ($ypos) {
$fname = '_DiffEngine::_lcs_pos';
//wfProfileIn( $fname );
$end = $this->lcs;
if ($end == 0 || $ypos > $this->seq[$end]) {
$this->seq[++$this->lcs] = $ypos;
$this->in_seq[$ypos] = 1;
//wfProfileOut( $fname );
return $this->lcs;
}
$beg = 1;
while ($beg < $end) {
$mid = (int)(($beg + $end) / 2);

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_DiffEngine::_line_hash (   $line)

Returns the whole line if it's small enough, or the MD5 hash otherwise.

Definition at line 867 of file class.WordLevelDiff.php.

{
_DiffEngine::_shift_boundaries (   $lines,
&  $changed,
  $other_changed 
)

Definition at line 1071 of file class.WordLevelDiff.php.

{
$fname = '_DiffEngine::_shift_boundaries';
//wfProfileIn( $fname );
$i = 0;
$j = 0;
USE_ASSERTS && assert('sizeof($lines) == sizeof($changed)');
$len = sizeof($lines);
$other_len = sizeof($other_changed);
while (1) {
/*
* Scan forwards to find 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]) {
USE_ASSERTS && 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])
$start--;
USE_ASSERTS && assert('$j > 0');
while ($other_changed[--$j])
continue;
USE_ASSERTS && 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])
$i++;
USE_ASSERTS && assert('$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);
/*
_DiffEngine::diff (   $from_lines,
  $to_lines 
)

Definition at line 771 of file class.WordLevelDiff.php.

{
const MAX_XREF_LENGTH = 10000;
function diff ($from_lines, $to_lines) {
$fname = '_DiffEngine::diff';
//wfProfileIn( $fname );
$n_from = sizeof($from_lines);
$n_to = sizeof($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++) {
$xhash[$this->_line_hash($from_lines[$xi])] = 1;
}
for ($yi = $skip; $yi < $n_to - $endskip; $yi++) {
$line = $to_lines[$yi];
if ( ($this->ychanged[$yi] = empty($xhash[$this->_line_hash($line)])) )
continue;
$yhash[$this->_line_hash($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($yhash[$this->_line_hash($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 < $n_to) {
USE_ASSERTS && assert($yi < $n_to || $this->xchanged[$xi]);
USE_ASSERTS && 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)
$edits[] = new _DiffOp_Copy($copy);
// Find deletes & adds.
$delete = array();
while ($xi < $n_from && $this->xchanged[$xi])
$delete[] = $from_lines[$xi++];

Field Documentation

const _DiffEngine::MAX_XREF_LENGTH = 10000

Definition at line 769 of file class.WordLevelDiff.php.

The documentation for this class was generated from the following file: