class/Text_Diff.php
<?php
/**
* Text_Diff
*
* 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 $
*
* @package Text_Diff
* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
*/
class Text_Diff
{
/**
* Array of changes.
*
* @var array
*/
public $_edits;
/**
* Computes diffs between sequences of strings.
*
* @param array $from_lines An array of strings. Typically these are
* lines from a file.
* @param array $to_lines An array of strings.
*/
public function __construct($from_lines, $to_lines)
{
array_walk($from_lines, array($this, '_trimNewlines'));
array_walk($to_lines, array($this, '_trimNewlines'));
if (extension_loaded('xdiff')) {
$engine = new Text_Diff_Engine_xdiff();
} else {
$engine = new Text_Diff_Engine_native();
}
$this->_edits = $engine->diff($from_lines, $to_lines);
}
/**
* Returns the array of differences.
*/
public function getDiff()
{
return $this->_edits;
}
/**
* Computes a reversed diff.
*
* Example:
* <code>
* $diff = new Text_Diff($lines1, $lines2);
* $rev = $diff->reverse();
* </code>
*
* @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()
* method.
*/
public function reverse()
{
if (version_compare(zend_version(), '2', '>')) {
$rev = clone$obj;
} else {
$rev = $this;
}
$rev->_edits = array();
foreach ($this->_edits as $edit) {
$rev->_edits[] = $edit->reverse();
}
return $rev;
}
/**
* Checks for an empty diff.
*
* @return boolean True if two sequences were identical.
*/
public function isEmpty()
{
foreach ($this->_edits as $edit) {
if (!is_a($edit, 'Text_Diff_Op_copy')) {
return false;
}
}
return true;
}
/**
* Computes the length of the Longest Common Subsequence (LCS).
*
* This is mostly for diagnostic purposes.
*
* @return integer The length of the LCS.
*/
public function lcs()
{
$lcs = 0;
foreach ($this->_edits as $edit) {
if (is_a($edit, 'Text_Diff_Op_copy')) {
$lcs += count($edit->orig);
}
}
return $lcs;
}
/**
* Gets the original set of lines.
*
* This reconstructs the $from_lines parameter passed to the constructor.
*
* @return array The original sequence of strings.
*/
public function getOriginal()
{
$lines = array();
foreach ($this->_edits as $edit) {
if ($edit->orig) {
array_splice($lines, count($lines), 0, $edit->orig);
}
}
return $lines;
}
/**
* Gets the final set of lines.
*
* This reconstructs the $to_lines parameter passed to the constructor.
*
* @return array The sequence of strings.
*/
public function getFinal()
{
$lines = array();
foreach ($this->_edits as $edit) {
if ($edit->final) {
array_splice($lines, count($lines), 0, $edit->final);
}
}
return $lines;
}
/**
* Removes trailing newlines from a line of text. This is meant to be used
* with array_walk().
*
* @param string $line The line to trim.
* @param integer $key The index of the line in the array. Not used.
*/
public function _trimNewlines(&$line, $key)
{
$line = str_replace(array("\n", "\r"), '', $line);
}
/**
* Checks a diff for validity.
*
* This is here only for debugging purposes.
* @param $from_lines
* @param $to_lines
* @return bool
*/
public function _check($from_lines, $to_lines)
{
if (serialize($from_lines) != serialize($this->getOriginal())) {
trigger_error("Reconstructed original doesn't match", E_USER_ERROR);
}
if (serialize($to_lines) != serialize($this->getFinal())) {
trigger_error("Reconstructed final doesn't match", E_USER_ERROR);
}
$rev = $this->reverse();
if (serialize($to_lines) != serialize($rev->getOriginal())) {
trigger_error("Reversed original doesn't match", E_USER_ERROR);
}
if (serialize($from_lines) != serialize($rev->getFinal())) {
trigger_error("Reversed final doesn't match", E_USER_ERROR);
}
$prevtype = null;
foreach ($this->_edits as $edit) {
if ($prevtype == get_class($edit)) {
trigger_error('Edit sequence is non-optimal', E_USER_ERROR);
}
$prevtype = get_class($edit);
}
return true;
}
}
/**
* $Horde: framework/Text_Diff/Diff.php,v 1.13 2005/05/26 20:26:06 selsky Exp $
*
* @package Text_Diff
* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
*/
class Text_MappedDiff extends Text_Diff
{
/**
* 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 $to_lines.
*/
public function __construct($from_lines, $to_lines, $mapped_from_lines, $mapped_to_lines)
{
assert(count($from_lines) == count($mapped_from_lines));
assert(count($to_lines) == count($mapped_to_lines));
parent::__construct($mapped_from_lines, $mapped_to_lines);
$xi = $yi = 0;
for ($i = 0; $i < count($this->_edits); $i++) {
$orig = &$this->_edits[$i]->orig;
if (is_array($orig)) {
$orig = array_slice($from_lines, $xi, count($orig));
$xi += count($orig);
}
$final = &$this->_edits[$i]->final;
if (is_array($final)) {
$final = array_slice($to_lines, $yi, count($final));
$yi += count($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>
* @package Text_Diff
*
* @access private
*/
class Text_Diff_Engine_xdiff
{
/**
* @param $from_lines
* @param $to_lines
* @return array
*/
public function diff($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));
$diff = explode("\n", $diff);
/* 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. */
$edits = array();
foreach ($diff as $line) {
switch ($line[0]) {
case ' ':
$edits[] = new Text_Diff_Op_copy(array(substr($line, 1)));
break;
case '+':
$edits[] = new Text_Diff_Op_add(array(substr($line, 1)));
break;
case '-':
$edits[] = new Text_Diff_Op_delete(array(substr($line, 1)));
break;
}
}
return $edits;
}
}
/**
* 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 Text_Diff
*
* @access private
*/
class Text_Diff_Engine_native
{
/**
* @param $from_lines
* @param $to_lines
* @return array
*/
public function diff($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 = $this->yind = array();
unset($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.
* @param $xoff
* @param $xlim
* @param $yoff
* @param $ylim
* @param $nchunks
* @return array
*/
public function _diag($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 = $this->_lcsPos($y);
assert($k > 0);
$ymids[$k] = $ymids[$k - 1];
break;
}
}
while (list($junk, $y) = each($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);
}
/**
* @param $ypos
* @return int
*/
public function _lcsPos($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.
* @param $xoff
* @param $xlim
* @param $yoff
* @param $ylim
*/
public function _compareseq($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).
* @param $lines
* @param $changed
* @param $other_changed
*/
public function _shiftBoundaries($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]');
}
}
}
}
/**
* @package Text_Diff
* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
*
* @access private
*/
class Text_Diff_Op
{
public $orig;
public $final;
public function reverse()
{
trigger_error('Abstract method', E_USER_ERROR);
}
/**
* @return int
*/
public function norig()
{
return $this->orig ? count($this->orig) : 0;
}
/**
* @return int
*/
public function nfinal()
{
return $this->final ? count($this->final) : 0;
}
}
/**
* @package Text_Diff
* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
*
* @access private
*/
class Text_Diff_Op_copy extends Text_Diff_Op
{
/**
* Text_Diff_Op_copy constructor.
* @param $orig
* @param bool $final
*/
public function __construct($orig, $final = false)
{
if (!is_array($final)) {
$final = $orig;
}
$this->orig = $orig;
$this->final = $final;
}
/**
* @return Text_Diff_Op_copy
*/
public function &reverse()
{
return $reverse = new Text_Diff_Op_copy($this->final, $this->orig);
}
}
/**
* @package Text_Diff
* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
*
* @access private
*/
class Text_Diff_Op_delete extends Text_Diff_Op
{
/**
* Text_Diff_Op_delete constructor.
* @param $lines
*/
public function __construct($lines)
{
$this->orig = $lines;
$this->final = false;
}
/**
* @return Text_Diff_Op_add
*/
public function &reverse()
{
return $reverse = new Text_Diff_Op_add($this->orig);
}
}
/**
* @package Text_Diff
* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
*
* @access private
*/
class Text_Diff_Op_add extends Text_Diff_Op
{
/**
* Text_Diff_Op_add constructor.
* @param $lines
*/
public function __construct($lines)
{
$this->final = $lines;
$this->orig = false;
}
/**
* @return Text_Diff_Op_delete
*/
public function &reverse()
{
return $reverse = new Text_Diff_Op_delete($this->final);
}
}
/**
* @package Text_Diff
* @author Geoffrey T. Dairiki <dairiki@dairiki.org>
*
* @access private
*/
class Text_Diff_Op_change extends Text_Diff_Op
{
/**
* Text_Diff_Op_change constructor.
* @param $orig
* @param $final
*/
public function __construct($orig, $final)
{
$this->orig = $orig;
$this->final = $final;
}
/**
* @return Text_Diff_Op_change
*/
public function &reverse()
{
return $reverse = new Text_Diff_Op_change($this->final, $this->orig);
}
}