// You may copy this code freely under the conditions of the GPL.
//
// FIXME: possibly remove assert()'s for production version?
// PHP3 does not have assert()
/**
*/
define('USE_ASSERTS', function_exists('assert'));
/**
* @package cms
* @subpackage core
* @access private
*/
class _DiffOp {
var $type;
var $orig;
var $final;
function reverse() {
trigger_error("pure virtual", E_USER_ERROR);
}
function norig() {
return $this->orig ? sizeof($this->orig) : 0;
}
function nfinal() {
return $this->final ? sizeof($this->final) : 0;
}
}
/**
* @package cms
* @subpackage core
* @access private
*/
class _DiffOp_Copy extends _DiffOp {
var $type = 'copy';
function _DiffOp_Copy ($orig, $final = false) {
if (!is_array($final))
$final = $orig;
$this->orig = $orig;
$this->final = $final;
}
function reverse() {
return new _DiffOp_Copy($this->final, $this->orig);
}
}
/**
* @package cms
* @subpackage core
* @access private
*/
class _DiffOp_Delete extends _DiffOp {
var $type = 'delete';
function _DiffOp_Delete ($lines) {
$this->orig = $lines;
$this->final = false;
}
function reverse() {
return new _DiffOp_Add($this->orig);
}
}
/**
* @package cms
* @subpackage core
* @access private
*/
class _DiffOp_Add extends _DiffOp {
var $type = 'add';
function _DiffOp_Add ($lines) {
$this->final = $lines;
$this->orig = false;
}
function reverse() {
return new _DiffOp_Delete($this->final);
}
}
/**
* @package cms
* @subpackage core
* @access private
*/
class _DiffOp_Change extends _DiffOp {
var $type = 'change';
function _DiffOp_Change ($orig, $final) {
$this->orig = $orig;
$this->final = $final;
}
function reverse() {
return new _DiffOp_Change($this->final, $this->orig);
}
}
/**
* Class used internally by Diff to actually compute the diffs.
*
* The algorithm used here is mostly lifted from the perl module
* Algorithm::Diff (version 1.06) by Ned Konz, which is available at:
* http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
*
* More ideas are taken from:
* http://www.ics.uci.edu/~eppstein/161/960229.html
*
* Some ideas are (and a bit of code) are from from analyze.c, from GNU
* diffutils-2.7, which can be found at:
* ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz
*
* Finally, some ideas (subdivision by NCHUNKS > 2, and some optimizations)
* are my own.
*
* @author Geoffrey T. Dairiki
* @access private
* @package cms
* @subpackage core
*/
class _DiffEngine
{
function diff ($from_lines, $to_lines) {
$n_from = sizeof($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++)
$xhash[$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 < $n_to) {
USE_ASSERTS && assert($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++];
$add = array();
while ($yi < $n_to && $this->ychanged[$yi])
$add[] = $to_lines[$yi++];
if ($delete && $add)
$edits[] = new _DiffOp_Change($delete, $add);
elseif ($delete)
$edits[] = new _DiffOp_Delete($delete);
elseif ($add)
$edits[] = new _DiffOp_Add($add);
}
return $edits;
}
/* Divide the Largest Common Subsequence (LCS) of the sequences
* [XOFF, XLIM) and [YOFF, YLIM) into NCHUNKS approximately equally
* sized segments.
*
* Returns (LCS, PTS). LCS is the length of the LCS. PTS is an
* array of NCHUNKS+1 (X, Y) indexes giving the diving points between
* sub sequences. The first sub-sequence is contained in [X0, X1),
* [Y0, Y1), the second in [X1, X2), [Y1, Y2) and so on. Note
* that (X0, Y0) == (XOFF, YOFF) and
* (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM).
*
* This function assumes that the first lines of the specified portions
* of the two files do not match, and likewise that the last lines do not
* match. The caller must trim matching lines from the beginning and end
* of the portions it is going to specify.
*/
function _diag ($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 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($matches);
while (list ($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];
}
}
}
}
$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 = $mid;
}
USE_ASSERTS && assert($ypos != $this->seq[$end]);
$this->in_seq[$this->seq[$end]] = false;
$this->seq[$end] = $ypos;
$this->in_seq[$ypos] = 1;
return $end;
}
/* Find 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 = $pt2;
}
}
}
/* Adjust inserts/deletes of identical lines to join changes
* as much as possible.
*
* We do something when a run of changed lines include a
* line at one end and has an excluded, identical line at the other.
* We are free to choose which identical line is included.
* `compareseq' usually chooses the one at the beginning,
* but usually it is cleaner to consider the following identical line
* to be the "change".
*
* This is extracted verbatim from analyze.c (GNU diffutils-2.7).
*/
function _shift_boundaries ($lines, &$changed, $other_changed) {
$i = 0;
$j = 0;
USE_ASSERTS && assert('sizeof($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 - $start);
/*
* If possible, move the fully-merged run of changes
* back to a corresponding run in the other file.
*/
while ($corresponding < $i) {
$changed[--$start] = 1;
$changed[--$i] = 0;
USE_ASSERTS && assert('$j > 0');
while ($other_changed[--$j])
continue;
USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
}
}
}
}
/**
* Class representing a 'diff' between two sequences of strings.
* @package cms
* @subpackage core
*/
class Diff
{
var $edits;
/**
* Constructor.
* Computes diff between sequences of strings.
*
* @param $from_lines array An array of strings.
* (Typically these are lines from a file.)
* @param $to_lines array An array of strings.
*/
function Diff($from_lines, $to_lines) {
$eng = new _DiffEngine;
$this->edits = $eng->diff($from_lines, $to_lines);
//$this->_check($from_lines, $to_lines);
}
/**
* Compute reversed Diff.
*
* SYNOPSIS:
*
* $diff = new Diff($lines1, $lines2);
* $rev = $diff->reverse();
* @return object A Diff object representing the inverse of the
* original diff.
*/
function reverse () {
$rev = $this;
$rev->edits = array();
foreach ($this->edits as $edit) {
$rev->edits[] = $edit->reverse();
}
return $rev;
}
/**
* Check for empty diff.
*
* @return bool True iff two sequences were identical.
*/
function isEmpty () {
foreach ($this->edits as $edit) {
if ($edit->type != 'copy')
return false;
}
return true;
}
/**
* Compute the length of the Longest Common Subsequence (LCS).
*
* This is mostly for diagnostic purposed.
*
* @return int The length of the LCS.
*/
function lcs () {
$lcs = 0;
foreach ($this->edits as $edit) {
if ($edit->type == 'copy')
$lcs += sizeof($edit->orig);
}
return $lcs;
}
/**
* Get the original set of lines.
*
* This reconstructs the $from_lines parameter passed to the
* constructor.
*
* @return array The original sequence of strings.
*/
function orig() {
$lines = array();
foreach ($this->edits as $edit) {
if ($edit->orig)
array_splice($lines, sizeof($lines), 0, $edit->orig);
}
return $lines;
}
/**
* Get the final set of lines.
*
* This reconstructs the $to_lines parameter passed to the
* constructor.
*
* @return array The sequence of strings.
*/
function finaltext() {
$lines = array();
foreach ($this->edits as $edit) {
if ($edit->final)
array_splice($lines, sizeof($lines), 0, $edit->final);
}
return $lines;
}
/**
* Check a Diff for validity.
*
* This is here only for debugging purposes.
*/
function _check ($from_lines, $to_lines) {
if (serialize($from_lines) != serialize($this->orig()))
trigger_error("Reconstructed original doesn't match", E_USER_ERROR);
if (serialize($to_lines) != serialize($this->finaltext()))
trigger_error("Reconstructed final doesn't match", E_USER_ERROR);
$rev = $this->reverse();
if (serialize($to_lines) != serialize($rev->orig()))
trigger_error("Reversed original doesn't match", E_USER_ERROR);
if (serialize($from_lines) != serialize($rev->finaltext()))
trigger_error("Reversed final doesn't match", E_USER_ERROR);
$prevtype = 'none';
foreach ($this->edits as $edit) {
if ( $prevtype == $edit->type )
trigger_error("Edit sequence is non-optimal", E_USER_ERROR);
$prevtype = $edit->type;
}
$lcs = $this->lcs();
trigger_error("Diff okay: LCS = $lcs", E_USER_NOTICE);
}
static function compareHTML($from, $to) {
// First split up the content into words and tags
$set1 = self::getHTMLChunks($from);
$set2 = self::getHTMLChunks($to);
// Diff that
$diff = new Diff($set1, $set2);
// Go through everything, converting edited tags (and their content) into single chunks. Otherwise
// the generated HTML gets crusty
foreach($diff->edits as $edit) {
//echo "$edit->type: " . htmlentities(implode(" " ,$edit->orig));
//if($edit->final) echo ' / ' . htmlentities(implode(" " ,$edit->final));
switch($edit->type) {
case 'copy':
$lookForTag = false;
$stuffFor[1] = $edit->orig;
$stuffFor[2] = $edit->orig;
break;
case 'change':
$lookForTag = true;
$stuffFor[1] = $edit->orig;
$stuffFor[2] = $edit->final;
break;
case 'add':
$lookForTag = true;
$stuffFor[1] = null;
$stuffFor[2] = $edit->final;
break;
case 'delete':
$lookForTag = true;
$stuffFor[1] = $edit->orig;
$stuffFor[2] = null;
break;
}
foreach($stuffFor as $listName => $chunks) {
if($chunks) {
foreach($chunks as $item) {
// $tagStack > 0 indicates that we should be tag-building
if(isset($tagStack[$listName])) $rechunked[$listName][sizeof($rechunked[$listName])-1] .= ' ' . $item;
else $rechunked[$listName][] = $item;
if($lookForTag && isset($item[0]) && $item[0] == "<" && substr($item,0,2) != "" . htmlentities($item) . " -> " .$tagStack[$listName];
}
}
}
}
// Diff the re-chunked data, turning it into maked up HTML
$diff = new Diff($rechunked[1], $rechunked[2]);
$content = '';
foreach($diff->edits as $edit) {
// echo "$edit->type: " . htmlentities(implode(" " ,$edit->orig));
// if($edit->final) echo ' / ' . htmlentities(implode(" " ,$edit->final));
switch($edit->type) {
case 'copy':
$content .= " " . implode(" ", $edit->orig) . " ";
break;
case 'change':
$content .= " " . implode(" ", $edit->final) . " ";
$content .= " " . implode(" ", $edit->orig) . " ";
break;
case 'add':
$content .= " " . implode(" ", $edit->final) . " ";
break;
case 'delete':
$content .= " " . implode(" ", $edit->orig) . " ";
break;
}
}
// echo "" . htmlentities($content) . "
";
return $content;
}
static function getHTMLChunks($content) {
$content = str_replace(array(" ","<", ">"),array(" "," <", "> "),$content);
$candidateChunks = split("[\t\r\n ]+", $content);
while(list($i,$item) = each($candidateChunks)) {
if(isset($item[0]) && $item[0] == "<") {
$newChunk = $item;
while($item[strlen($item)-1] != ">") {
list($i,$item) = each($candidateChunks);
$newChunk .= ' ' . $item;
}
$chunks[] = $newChunk;
} else {
$chunks[] = $item;
}
}
return $chunks;
}
}
/**
* Computes diff between sequences of strings.
* @package cms
* @subpackage core
*/
class MappedDiff
extends Diff
{
/**
* Constructor.
*
* Computes 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 $from_lines array An array of strings.
* (Typically these are lines from a file.)
*
* @param $to_lines array An array of strings.
*
* @param $mapped_from_lines array 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 $mapped_to_lines array This array should
* have the same number of elements as $to_lines.
*/
function MappedDiff($from_lines, $to_lines,
$mapped_from_lines, $mapped_to_lines) {
assert(sizeof($from_lines) == sizeof($mapped_from_lines));
assert(sizeof($to_lines) == sizeof($mapped_to_lines));
$this->Diff($mapped_from_lines, $mapped_to_lines);
$xi = $yi = 0;
// Optimizing loop invariants:
// http://phplens.com/lens/php-book/optimizing-debugging-php.php
for ($i = 0, $max = sizeof($this->edits); $i < $max; $i++) {
$orig = &$this->edits[$i]->orig;
if (is_array($orig)) {
$orig = array_slice($from_lines, $xi, sizeof($orig));
$xi += sizeof($orig);
}
$final = &$this->edits[$i]->final;
if (is_array($final)) {
$final = array_slice($to_lines, $yi, sizeof($final));
$yi += sizeof($final);
}
}
}
}
?>