Source for file Diff.php
Documentation is available at Diff.php
* 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 $
* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
* Computes diffs between sequences of strings.
* @param array $from_lines An array of strings. Typically these are
* @param array $to_lines An array of strings.
array_walk($from_lines, array ($this, '_trimNewlines'));
array_walk($to_lines, array ($this, '_trimNewlines'));
$engine = &new Text_Diff_Engine_xdiff ();
$engine = &new Text_Diff_Engine_native ();
$this->_edits = $engine->diff ($from_lines, $to_lines);
* Returns the array of differences.
* Computes a reversed diff.
* $diff = &new Text_Diff($lines1, $lines2);
* $rev = $diff->reverse();
* @return Text_Diff A Diff object representing the inverse of the
* original diff. Note that we purposely don't return a
* reference here, since this essentially is a clone()
foreach ($this->_edits as $edit) {
$rev->_edits [] = $edit->reverse ();
* Checks for an empty diff.
* @return boolean True if two sequences were identical.
foreach ($this->_edits as $edit) {
if (!is_a($edit, 'Text_Diff_Op_copy')) {
* Computes the length of the Longest Common Subsequence (LCS).
* This is mostly for diagnostic purposes.
* @return integer The length of the LCS.
foreach ($this->_edits as $edit) {
if (is_a($edit, 'Text_Diff_Op_copy')) {
$lcs += count($edit->orig );
* Gets the original set of lines.
* This reconstructs the $from_lines parameter passed to the constructor.
* @return array The original sequence of strings.
foreach ($this->_edits as $edit) {
* Gets the final set of lines.
* This reconstructs the $to_lines parameter passed to the constructor.
* @return array The sequence of strings.
foreach ($this->_edits as $edit) {
* Removes trailing newlines from a line of text. This is meant to be used
* @param string $line The line to trim.
* @param integer $key The index of the line in the array. Not used.
function _trimNewlines (&$line, $key)
* Checks a diff for validity.
* This is here only for debugging purposes.
function _check ($from_lines, $to_lines)
trigger_error("Reconstructed original doesn't match", E_USER_ERROR );
trigger_error("Reconstructed final doesn't match", E_USER_ERROR );
foreach ($this->_edits as $edit) {
* $Horde: framework/Text_Diff/Diff.php,v 1.13 2005/05/26 20:26:06 selsky Exp $
* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
* 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.
$mapped_from_lines, $mapped_to_lines)
parent ::Text_Diff($mapped_from_lines, $mapped_to_lines);
for ($i = 0; $i < count($this->_edits); $i++ ) {
$orig = &$this->_edits[$i]->orig;
$final = &$this->_edits[$i]->final;
* Class used internally by Diff to actually compute the diffs. This class
* uses the xdiff PECL package (http://pecl.php.net/package/xdiff) to compute
* the differences between the two input arrays.
* @author Jon Parise <jon@horde.org>
class Text_Diff_Engine_xdiff {
function diff ($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));
/* 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 $edits array. The result is still perfectly
* valid, albeit a little less descriptive and efficient. */
foreach ($diff as $line) {
$edits[] = &new Text_Diff_Op_copy (array (substr($line, 1 )));
$edits[] = &new Text_Diff_Op_add (array (substr($line, 1 )));
$edits[] = &new Text_Diff_Op_delete (array (substr($line, 1 )));
* 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>
class Text_Diff_Engine_native {
function diff ($from_lines, $to_lines)
$n_from = count($from_lines);
$n_to = count($to_lines);
$this->xchanged = $this->ychanged = array ();
$this->xv = $this->yv = array ();
$this->xind = $this->yind = array ();
// Skip leading common lines.
for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++ ) {
if ($from_lines[$skip] != $to_lines[$skip]) {
$this->xchanged[$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]) {
$this->xchanged[$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; $yi++ ) {
if (($this->ychanged[$yi] = empty ($xhash[$line]))) {
for ($xi = $skip; $xi < $n_from - $endskip; $xi++ ) {
$line = $from_lines[$xi];
if (($this->xchanged[$xi] = empty ($yhash[$line]))) {
$this->_compareseq (0 , count($this->xv), 0 , count($this->yv));
// Merge edits when possible.
$this->_shiftBoundaries ($from_lines, $this->xchanged, $this->ychanged);
$this->_shiftBoundaries ($to_lines, $this->ychanged, $this->xchanged);
// Compute the edit operations.
while ($xi < $n_from || $yi < $n_to) {
assert($yi < $n_to || $this->xchanged[$xi]);
assert($xi < $n_from || $this->ychanged[$yi]);
// Skip matching "snake".
while ($xi < $n_from && $yi < $n_to
&& !$this->xchanged[$xi] && !$this->ychanged[$yi]) {
$copy[] = $from_lines[$xi++ ];
$edits[] = &new Text_Diff_Op_copy ($copy);
while ($xi < $n_from && $this->xchanged[$xi]) {
$delete[] = $from_lines[$xi++ ];
while ($yi < $n_to && $this->ychanged[$yi]) {
$add[] = $to_lines[$yi++ ];
$edits[] = &new Text_Diff_Op_change ($delete, $add);
$edits[] = &new Text_Diff_Op_delete ($delete);
$edits[] = &new Text_Diff_Op_add ($add);
* Divides the Largest Common Subsequence (LCS) of the sequences (XOFF,
* XLIM) and (YOFF, YLIM) into NCHUNKS approximately equally sized
* 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, $nchunks)
if ($xlim - $xoff > $ylim - $yoff) {
/* Things seems faster (I'm not sure I understand why) when the
* shortest sequence is in X. */
list ($xoff, $xlim, $yoff, $ylim)
= array ($yoff, $ylim, $xoff, $xlim);
for ($i = $ylim - 1; $i >= $yoff; $i-- ) {
$ymatches[$this->xv[$i]][] = $i;
for ($i = $ylim - 1; $i >= $yoff; $i-- ) {
$ymatches[$this->yv[$i]][] = $i;
$this->seq[0 ]= $yoff - 1;
$numer = $xlim - $xoff + $nchunks - 1;
for ($chunk = 0; $chunk < $nchunks; $chunk++ ) {
for ($i = 0; $i <= $this->lcs; $i++ ) {
$ymids[$i][$chunk - 1 ] = $this->seq[$i];
$x1 = $xoff + (int) (($numer + ($xlim- $xoff)* $chunk) / $nchunks);
$line = $flip ? $this->yv[$x] : $this->xv[$x];
if (empty ($ymatches[$line])) {
$matches = $ymatches[$line];
foreach ($matches as $y) {
if (empty ($this->in_seq[$y])) {
$ymids[$k] = $ymids[$k - 1 ];
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[$k]] = false;
} elseif (empty ($this->in_seq[$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);
$seps[] = $flip ? array ($y1, $x1) : array ($x1, $y1);
$seps[] = $flip ? array ($ylim, $xlim) : array ($xlim, $ylim);
return array ($this->lcs, $seps);
if ($end == 0 || $ypos > $this->seq[$end]) {
$this->seq[++ $this->lcs] = $ypos;
$this->in_seq[$ypos] = 1;
$mid = (int) (($beg + $end) / 2 );
if ($ypos > $this->seq[$mid]) {
assert($ypos != $this->seq[$end]);
$this->in_seq[$this->seq[$end]] = false;
$this->seq[$end] = $ypos;
$this->in_seq[$ypos] = 1;
* 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]) {
/* Slide up the top initial diagonal. */
while ($xlim > $xoff && $ylim > $yoff
&& $this->xv[$xlim - 1 ] == $this->yv[$ylim - 1 ]) {
if ($xoff == $xlim || $yoff == $ylim) {
/* 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;
= $this->_diag ($xoff, $xlim, $yoff, $ylim, $nchunks);
/* X and Y sequences have no common subsequence: mark all
$this->ychanged[$this->yind[$yoff++ ]] = 1;
$this->xchanged[$this->xind[$xoff++ ]] = 1;
/* Use the partitions to split this problem into subproblems. */
while ($pt2 = next($seps)) {
$this->_compareseq ($pt1[0 ], $pt2[0 ], $pt1[1 ], $pt2[1 ]);
* Adjusts inserts/deletes of identical lines to join changes as much as
* We do something when a run of changed lines include a line at one end
* and has an excluded, identical line at the other. We are free to
* choose which identical line is included. `compareseq' usually chooses
* the one at the beginning, but usually it is cleaner to consider the
* following identical line to be the "change".
* This is extracted verbatim from analyze.c (GNU diffutils-2.7).
function _shiftBoundaries ($lines, &$changed, $other_changed)
assert('count($lines) == count($changed)');
$other_len = count($other_changed);
/* Scan forward to find the beginning of another run of
* changes. Also keep track of the corresponding point in the
* 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
* Furthermore, $j is always kept so that $j == $other_len or
* $other_changed[$j] == false. */
while ($j < $other_len && $other_changed[$j]) {
while ($i < $len && ! $changed[$i]) {
assert('$j < $other_len && ! $other_changed[$j]');
while ($j < $other_len && $other_changed[$j]) {
/* Find the end of this run of changes. */
while (++ $i < $len && $changed[$i]) {
/* 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 ]) {
while ($start > 0 && $changed[$start - 1 ]) {
while ($other_changed[-- $j]) {
assert('$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
$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;
while ($i < $len && $changed[$i]) {
assert('$j < $other_len && ! $other_changed[$j]');
if ($j < $other_len && $other_changed[$j]) {
while ($j < $other_len && $other_changed[$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 < $i) {
while ($other_changed[-- $j]) {
assert('$j >= 0 && !$other_changed[$j]');
* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
return $this->orig ? count($this->orig) : 0;
return $this->final ? count($this->final) : 0;
* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
class Text_Diff_Op_copy extends Text_Diff_Op {
function Text_Diff_Op_copy ($orig, $final = false )
return $reverse = &new Text_Diff_Op_copy ($this->final, $this->orig);
* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
class Text_Diff_Op_delete extends Text_Diff_Op {
function Text_Diff_Op_delete ($lines)
return $reverse = &new Text_Diff_Op_add ($this->orig);
* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
class Text_Diff_Op_add extends Text_Diff_Op {
function Text_Diff_Op_add ($lines)
return $reverse = &new Text_Diff_Op_delete ($this->final);
* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
class Text_Diff_Op_change extends Text_Diff_Op {
function Text_Diff_Op_change ($orig, $final)
return $reverse = &new Text_Diff_Op_change ($this->final, $this->orig);
Documentation generated on Mon, 11 Mar 2019 14:16:38 -0400 by phpDocumentor 1.4.4. PEAR Logo Copyright © PHP Group 2004.
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