<?php
/*
* Copyright (C) 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
*
* This file is part of PhpWiki.
*
* PhpWiki is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* PhpWiki is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with PhpWiki; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
// difflib.php
//
// A PHP diff engine for phpwiki.
abstract class DiffOp
{
public $type;
public $orig;
public $final;
abstract public function reverse();
public function norig()
{
return $this->orig ? sizeof($this->orig) : 0;
}
public function nfinal()
{
return $this->final ? sizeof($this->final) : 0;
}
}
class DiffOp_Copy extends DiffOp
{
public $type = 'copy';
function __construct($orig, $final = false)
{
if (!is_array($final))
$final = $orig;
$this->orig = $orig;
$this->final = $final;
}
public function reverse()
{
return new DiffOp_Copy($this->final, $this->orig);
}
}
class DiffOp_Delete extends DiffOp
{
public $type = 'delete';
function __construct($lines)
{
$this->orig = $lines;
$this->final = false;
}
public function reverse()
{
return new DiffOp_Add($this->orig);
}
}
class DiffOp_Add extends DiffOp
{
public $type = 'add';
function __construct($lines)
{
$this->final = $lines;
$this->orig = false;
}
public function reverse()
{
return new DiffOp_Delete($this->final);
}
}
class DiffOp_Change extends DiffOp
{
public $type = 'change';
function __construct($orig, $final)
{
$this->orig = $orig;
$this->final = $final;
}
public function reverse()
{
return new DiffOp_Change($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
*/
class DiffEngine
{
public $xchanged;
public $ychanged;
public $xv;
public $yv;
public $xind;
public $yind;
public $lcs;
public $seq;
public $in_seq;
public function diff($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 < $n_to) {
assert($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)
$edits[] = new DiffOp_Copy($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 $edits;
}
/* Divide the Largest Common Subsequence (LCS) of the sequences
* [XOFF, XLIM) and [YOFF, YLIM) into NCHUNKS approximately equally
* sized segments.
*
* Returns (LCS, PTS). LCS is the length of the LCS. PTS is an
* array of NCHUNKS+1 (X, Y) indexes giving the diving points between
* sub sequences. The first sub-sequence is contained in [X0, X1),
* [Y0, Y1), the second in [X1, X2), [Y1, Y2) and so on. Note
* that (X0, Y0) == (XOFF, YOFF) and
* (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM).
*
* This function assumes that the first lines of the specified portions
* of the two files do not match, and likewise that the last lines do not
* match. The caller must trim matching lines from the beginning and end
* of the portions it is going to specify.
*/
private function diag($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);
$pointer = 0;
foreach ($matches as $y) {
$pointer++;
if (empty($this->in_seq[$y])) {
$k = $this->lcs_pos($y);
assert($k > 0);
$ymids[$k] = $ymids[$k - 1];
break;
}
}
foreach (array_slice($matches, $pointer) as $y) {
if ($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 = $this->lcs_pos($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, $seps);
}
private function lcs_pos($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 = $mid;
}
assert($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 $this->{x,y}changed[], by
* storing a 1 in the element for each line that is an insertion
* or deletion (ie. is not in the LCS).
*
* The subsequence of file 0 is [XOFF, XLIM) and likewise for file 1.
*
* Note that XLIM, YLIM are exclusive bounds.
* All line numbers are origin-0 and discarded lines are not counted.
*/
private function compareseq($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 = $pt2;
}
}
}
/* Adjust inserts/deletes of identical lines to join changes
* as much as possible.
*
* We do something when a run of changed lines include a
* line at one end and has an excluded, identical line at the other.
* We are free to choose which identical line is included.
* `compareseq' usually chooses the one at the beginning,
* but usually it is cleaner to consider the following identical line
* to be the "change".
*
* This is extracted verbatim from analyze.c (GNU diffutils-2.7).
*/
private function shift_boundaries($lines, &$changed, $other_changed)
{
$i = 0;
$j = 0;
assert(sizeof($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[$i]) {
assert($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]);
}
}
}
}
/**
* Class representing a 'diff' between two sequences of strings.
*/
class Diff
{
public $edits;
/**
* Computes diff between sequences of strings.
*
* @param $from_lines array An array of strings.
* (Typically these are lines from a file.)
* @param $to_lines array An array of strings.
*/
function __construct($from_lines, $to_lines)
{
$eng = new DiffEngine();
$this->edits = $eng->diff($from_lines, $to_lines);
}
/**
* Check for empty diff.
*
* @return bool True iff two sequences were identical.
*/
public function isEmpty()
{
foreach ($this->edits as $edit) {
if ($edit->type != 'copy')
return false;
}
return true;
}
/**
* Get the original set of lines.
*
* This reconstructs the $from_lines parameter passed to the
* constructor.
*
* @return array The original sequence of strings.
*/
public 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.
*/
public function finalize()
{
$lines = array();
foreach ($this->edits as $edit) {
if ($edit->final)
array_splice($lines, sizeof($lines), 0, $edit->final);
}
return $lines;
}
}
/**
* FIXME: bad name.
*/
class MappedDiff
extends Diff
{
/**
* 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 $to_lines.
*/
function __construct($from_lines, $to_lines,
$mapped_from_lines, $mapped_to_lines)
{
assert(sizeof($from_lines) == sizeof($mapped_from_lines));
assert(sizeof($to_lines) == sizeof($mapped_to_lines));
parent::__construct($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);
}
}
}
}
/**
* A class to format Diffs
*
* This class formats the diff in classic diff format.
* It is intended that this class be customized via inheritance,
* to obtain fancier outputs.
*/
class DiffFormatter
{
/**
* Number of leading context "lines" to preserve.
*
* This should be left at zero for this class, but subclasses
* may want to set this to other values.
*/
public $leading_context_lines = 0;
/**
* Number of trailing context "lines" to preserve.
*
* This should be left at zero for this class, but subclasses
* may want to set this to other values.
*/
public $trailing_context_lines = 0;
/**
* Format a diff.
*
* @param $diff object A Diff object.
* @return string The formatted output.
*/
public function format($diff)
{
$xi = $yi = 1;
$block = false;
$context = array();
$nlead = $this->leading_context_lines;
$ntrail = $this->trailing_context_lines;
$this->start_diff();
$x0 = 0;
$y0 = 0;
foreach ($diff->edits as $edit) {
if ($edit->type == 'copy') {
if (is_array($block)) {
if (sizeof($edit->orig) <= $nlead + $ntrail) {
$block[] = $edit;
} else {
if ($ntrail) {
$context = array_slice($edit->orig, 0, $ntrail);
$block[] = new DiffOp_Copy($context);
}
$this->block($x0, $ntrail + $xi - $x0,
$y0, $ntrail + $yi - $y0,
$block);
$block = false;
}
}
$context = $edit->orig;
} else {
if (!is_array($block)) {
$context = array_slice($context, max(0, sizeof($context) - $nlead));
$x0 = $xi - sizeof($context);
$y0 = $yi - sizeof($context);
$block = array();
if ($context)
$block[] = new DiffOp_Copy($context);
}
$block[] = $edit;
}
if ($edit->orig)
$xi += sizeof($edit->orig);
if ($edit->final)
$yi += sizeof($edit->final);
}
if (is_array($block))
$this->block($x0, $xi - $x0,
$y0, $yi - $y0,
$block);
return $this->end_diff();
}
private function block($xbeg, $xlen, $ybeg, $ylen, &$edits)
{
$this->start_block($this->block_header($xbeg, $xlen, $ybeg, $ylen));
foreach ($edits as $edit) {
if ($edit->type == 'copy')
$this->context($edit->orig);
elseif ($edit->type == 'add')
$this->added($edit->final);
elseif ($edit->type == 'delete')
$this->deleted($edit->orig);
elseif ($edit->type == 'change')
$this->changed($edit->orig, $edit->final);
else
trigger_error("Unknown edit type", E_USER_ERROR);
}
$this->end_block();
}
protected function start_diff()
{
ob_start();
}
protected function end_diff()
{
$val = ob_get_contents();
ob_end_clean();
return $val;
}
protected function block_header($xbeg, $xlen, $ybeg, $ylen)
{
if ($xlen > 1)
$xbeg .= "," . ($xbeg + $xlen - 1);
if ($ylen > 1)
$ybeg .= "," . ($ybeg + $ylen - 1);
return $xbeg . ($xlen ? ($ylen ? 'c' : 'd') : 'a') . $ybeg;
}
protected function start_block($header)
{
echo $header;
}
protected function end_block()
{
}
protected function lines($lines, $prefix = ' ')
{
foreach ($lines as $line)
echo "$prefix $line\n";
}
protected function context($lines)
{
$this->lines($lines);
}
protected function added($lines)
{
$this->lines($lines, ">");
}
protected function deleted($lines)
{
$this->lines($lines, "<");
}
protected function changed($orig, $final)
{
$this->deleted($orig);
echo "---\n";
$this->added($final);
}
}
/**
* "Unified" diff formatter.
*
* This class formats the diff in classic "unified diff" format.
*/
class UnifiedDiffFormatter extends DiffFormatter
{
function __construct($context_lines = 4)
{
$this->leading_context_lines = $context_lines;
$this->trailing_context_lines = $context_lines;
}
protected function block_header($xbeg, $xlen, $ybeg, $ylen)
{
if ($xlen != 1)
$xbeg .= "," . $xlen;
if ($ylen != 1)
$ybeg .= "," . $ylen;
return "@@ -$xbeg +$ybeg @@\n";
}
protected function added($lines)
{
$this->lines($lines, "+");
}
protected function deleted($lines)
{
$this->lines($lines, "-");
}
protected function changed($orig, $final)
{
$this->deleted($orig);
$this->added($final);
}
}
/**
* block conflict diff formatter.
*
* This class will format a diff identical to Diff3 (i.e. editpage
* conflicts), but when there are only two source files. To be used by
* future enhancements to reloading / upgrading pgsrc.
*
* Functional but not finished yet, need to eliminate redundant block
* suffixes (i.e. "=======" immediately followed by another prefix)
* see class LoadFileConflictPageEditor
*/
class BlockDiffFormatter extends DiffFormatter
{
function __construct($context_lines = 4)
{
$this->leading_context_lines = $context_lines;
$this->trailing_context_lines = $context_lines;
}
protected function lines($lines, $prefix = '')
{
if (!$prefix == '')
echo "$prefix\n";
foreach ($lines as $line)
echo "$line\n";
if (!$prefix == '')
echo "$prefix\n";
}
protected function added($lines)
{
$this->lines($lines, ">>>>>>>");
}
protected function deleted($lines)
{
$this->lines($lines, "<<<<<<<");
}
protected function block_header($xbeg, $xlen, $ybeg, $ylen)
{
return "";
}
protected function changed($orig, $final)
{
$this->deleted($orig);
$this->added($final);
}
}