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<?php
/**
* A PHP diff engine for phpwiki. (Taken from phpwiki-1.3.3)
*
* Copyright © 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
* You may copy this code freely under the conditions of the GPL.
*
* This program 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.
*
* This program 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 this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
* @ingroup DifferenceEngine
* @defgroup DifferenceEngine DifferenceEngine
*/
/**
* The base class for all other DiffOp classes.
*
* The classes that extend DiffOp are: DiffOpCopy, DiffOpDelete, DiffOpAdd and
* DiffOpChange. FakeDiffOp also extends DiffOp, but it is not located in this file.
*
* @private
* @ingroup DifferenceEngine
*/
abstract class DiffOp {
/**
* @var string
*/
public $type;
/**
* @var string[]
*/
public $orig;
/**
* @var string[]
*/
public $closing;
/**
* @return string
*/
public function getType() {
return $this->type;
}
/**
* @return string[]
*/
public function getOrig() {
return $this->orig;
}
/**
* @param int $i
* @return string|null
*/
public function getClosing( $i = null ) {
if ( $i === null ) {
return $this->closing;
}
if ( array_key_exists( $i, $this->closing ) ) {
return $this->closing[$i];
}
return null;
}
abstract public function reverse();
/**
* @return int
*/
public function norig() {
return $this->orig ? count( $this->orig ) : 0;
}
/**
* @return int
*/
public function nclosing() {
return $this->closing ? count( $this->closing ) : 0;
}
}
/**
* Extends DiffOp. Used to mark strings that have been
* copied from one string array to the other.
*
* @private
* @ingroup DifferenceEngine
*/
class DiffOpCopy extends DiffOp {
public $type = 'copy';
public function __construct( $orig, $closing = false ) {
if ( !is_array( $closing ) ) {
$closing = $orig;
}
$this->orig = $orig;
$this->closing = $closing;
}
/**
* @return DiffOpCopy
*/
public function reverse() {
return new DiffOpCopy( $this->closing, $this->orig );
}
}
/**
* Extends DiffOp. Used to mark strings that have been
* deleted from the first string array.
*
* @private
* @ingroup DifferenceEngine
*/
class DiffOpDelete extends DiffOp {
public $type = 'delete';
public function __construct( $lines ) {
$this->orig = $lines;
$this->closing = false;
}
/**
* @return DiffOpAdd
*/
public function reverse() {
return new DiffOpAdd( $this->orig );
}
}
/**
* Extends DiffOp. Used to mark strings that have been
* added from the first string array.
*
* @private
* @ingroup DifferenceEngine
*/
class DiffOpAdd extends DiffOp {
public $type = 'add';
public function __construct( $lines ) {
$this->closing = $lines;
$this->orig = false;
}
/**
* @return DiffOpDelete
*/
public function reverse() {
return new DiffOpDelete( $this->closing );
}
}
/**
* Extends DiffOp. Used to mark strings that have been
* changed from the first string array (both added and subtracted).
*
* @private
* @ingroup DifferenceEngine
*/
class DiffOpChange extends DiffOp {
public $type = 'change';
public function __construct( $orig, $closing ) {
$this->orig = $orig;
$this->closing = $closing;
}
/**
* @return DiffOpChange
*/
public function reverse() {
return new DiffOpChange( $this->closing, $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 (and a bit of code) are 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
*
* closingly, some ideas (subdivision by NCHUNKS > 2, and some optimizations)
* are my own.
*
* Line length limits for robustness added by Tim Starling, 2005-08-31
* Alternative implementation added by Guy Van den Broeck, 2008-07-30
*
* @author Geoffrey T. Dairiki, Tim Starling, Guy Van den Broeck
* @private
* @ingroup DifferenceEngine
*/
class DiffEngine {
const MAX_XREF_LENGTH = 10000;
protected $xchanged, $ychanged;
protected $xv = [], $yv = [];
protected $xind = [], $yind = [];
protected $seq = [], $in_seq = [];
protected $lcs = 0;
/**
* @param string[] $from_lines
* @param string[] $to_lines
*
* @return DiffOp[]
*/
public function diff( $from_lines, $to_lines ) {
// Diff and store locally
$this->diffLocal( $from_lines, $to_lines );
// Merge edits when possible
$this->shiftBoundaries( $from_lines, $this->xchanged, $this->ychanged );
$this->shiftBoundaries( $to_lines, $this->ychanged, $this->xchanged );
// Compute the edit operations.
$n_from = count( $from_lines );
$n_to = count( $to_lines );
$edits = [];
$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 = [];
while ( $xi < $n_from && $yi < $n_to
&& !$this->xchanged[$xi] && !$this->ychanged[$yi]
) {
$copy[] = $from_lines[$xi++];
++$yi;
}
if ( $copy ) {
$edits[] = new DiffOpCopy( $copy );
}
// Find deletes & adds.
$delete = [];
while ( $xi < $n_from && $this->xchanged[$xi] ) {
$delete[] = $from_lines[$xi++];
}
$add = [];
while ( $yi < $n_to && $this->ychanged[$yi] ) {
$add[] = $to_lines[$yi++];
}
if ( $delete && $add ) {
$edits[] = new DiffOpChange( $delete, $add );
} elseif ( $delete ) {
$edits[] = new DiffOpDelete( $delete );
} elseif ( $add ) {
$edits[] = new DiffOpAdd( $add );
}
}
return $edits;
}
/**
* @param string[] $from_lines
* @param string[] $to_lines
*/
private function diffLocal( $from_lines, $to_lines ) {
$wikidiff3 = new WikiDiff3();
$wikidiff3->diff( $from_lines, $to_lines );
$this->xchanged = $wikidiff3->removed;
$this->ychanged = $wikidiff3->added;
}
/**
* 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 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 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.
* @todo document
* @private
* @ingroup DifferenceEngine
*/
class Diff {
/**
* @var DiffOp[]
*/
public $edits;
/**
* Constructor.
* Computes diff between sequences of strings.
*
* @param string[] $from_lines An array of strings.
* Typically these are lines from a file.
* @param string[] $to_lines An array of strings.
*/
public function __construct( $from_lines, $to_lines ) {
$eng = new DiffEngine;
$this->edits = $eng->diff( $from_lines, $to_lines );
}
/**
* @return DiffOp[]
*/
public function getEdits() {
return $this->edits;
}
/**
* Compute reversed Diff.
*
* SYNOPSIS:
*
* $diff = new Diff($lines1, $lines2);
* $rev = $diff->reverse();
*
* @return Object A Diff object representing the inverse of the
* original diff.
*/
public function reverse() {
$rev = $this;
$rev->edits = [];
/** @var DiffOp $edit */
foreach ( $this->edits as $edit ) {
$rev->edits[] = $edit->reverse();
}
return $rev;
}
/**
* Check for empty diff.
*
* @return bool True if two sequences were identical.
*/
public 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.
*/
public function lcs() {
$lcs = 0;
foreach ( $this->edits as $edit ) {
if ( $edit->type == 'copy' ) {
$lcs += count( $edit->orig );
}
}
return $lcs;
}
/**
* Get the original set of lines.
*
* This reconstructs the $from_lines parameter passed to the
* constructor.
*
* @return string[] The original sequence of strings.
*/
public function orig() {
$lines = [];
foreach ( $this->edits as $edit ) {
if ( $edit->orig ) {
array_splice( $lines, count( $lines ), 0, $edit->orig );
}
}
return $lines;
}
/**
* Get the closing set of lines.
*
* This reconstructs the $to_lines parameter passed to the
* constructor.
*
* @return string[] The sequence of strings.
*/
public function closing() {
$lines = [];
foreach ( $this->edits as $edit ) {
if ( $edit->closing ) {
array_splice( $lines, count( $lines ), 0, $edit->closing );
}
}
return $lines;
}
}
/**
* @todo document, bad name.
* @private
* @ingroup DifferenceEngine
*/
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 string[] $from_lines An array of strings.
* Typically these are lines from a file.
* @param string[] $to_lines An array of strings.
* @param string[] $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 string[] $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;
$editCount = count( $this->edits );
for ( $i = 0; $i < $editCount; $i++ ) {
$orig = &$this->edits[$i]->orig;
if ( is_array( $orig ) ) {
$orig = array_slice( $from_lines, $xi, count( $orig ) );
$xi += count( $orig );
}
$closing = &$this->edits[$i]->closing;
if ( is_array( $closing ) ) {
$closing = array_slice( $to_lines, $yi, count( $closing ) );
$yi += count( $closing );
}
}
}
}
/**
* Additions by Axel Boldt follow, partly taken from diff.php, phpwiki-1.3.3
*/
/**
* @todo document
* @private
* @ingroup DifferenceEngine
*/
class HWLDFWordAccumulator {
public $insClass = ' class="diffchange diffchange-inline"';
public $delClass = ' class="diffchange diffchange-inline"';
private $lines = [];
private $line = '';
private $group = '';
private $tag = '';
/**
* @param string $new_tag
*/
private function flushGroup( $new_tag ) {
if ( $this->group !== '' ) {
if ( $this->tag == 'ins' ) {
$this->line .= "<ins{$this->insClass}>" .
htmlspecialchars( $this->group ) . '</ins>';
} elseif ( $this->tag == 'del' ) {
$this->line .= "<del{$this->delClass}>" .
htmlspecialchars( $this->group ) . '</del>';
} else {
$this->line .= htmlspecialchars( $this->group );
}
}
$this->group = '';
$this->tag = $new_tag;
}
/**
* @param string $new_tag
*/
private function flushLine( $new_tag ) {
$this->flushGroup( $new_tag );
if ( $this->line != '' ) {
array_push( $this->lines, $this->line );
} else {
# make empty lines visible by inserting an NBSP
array_push( $this->lines, ' ' );
}
$this->line = '';
}
/**
* @param string[] $words
* @param string $tag
*/
public function addWords( $words, $tag = '' ) {
if ( $tag != $this->tag ) {
$this->flushGroup( $tag );
}
foreach ( $words as $word ) {
// new-line should only come as first char of word.
if ( $word == '' ) {
continue;
}
if ( $word[0] == "\n" ) {
$this->flushLine( $tag );
$word = substr( $word, 1 );
}
assert( !strstr( $word, "\n" ) );
$this->group .= $word;
}
}
/**
* @return string[]
*/
public function getLines() {
$this->flushLine( '~done' );
return $this->lines;
}
}
/**
* @todo document
* @private
* @ingroup DifferenceEngine
*/
class WordLevelDiff extends MappedDiff {
const MAX_LINE_LENGTH = 10000;
/**
* @param string[] $orig_lines
* @param string[] $closing_lines
*/
public function __construct( $orig_lines, $closing_lines ) {
list( $orig_words, $orig_stripped ) = $this->split( $orig_lines );
list( $closing_words, $closing_stripped ) = $this->split( $closing_lines );
parent::__construct( $orig_words, $closing_words,
$orig_stripped, $closing_stripped );
}
/**
* @param string[] $lines
*
* @return array[]
*/
private function split( $lines ) {
$words = [];
$stripped = [];
$first = true;
foreach ( $lines as $line ) {
# If the line is too long, just pretend the entire line is one big word
# This prevents resource exhaustion problems
if ( $first ) {
$first = false;
} else {
$words[] = "\n";
$stripped[] = "\n";
}
if ( strlen( $line ) > self::MAX_LINE_LENGTH ) {
$words[] = $line;
$stripped[] = $line;
} else {
$m = [];
if ( preg_match_all( '/ ( [^\S\n]+ | [0-9_A-Za-z\x80-\xff]+ | . ) (?: (?!< \n) [^\S\n])? /xs',
$line, $m )
) {
foreach ( $m[0] as $word ) {
$words[] = $word;
}
foreach ( $m[1] as $stripped_word ) {
$stripped[] = $stripped_word;
}
}
}
}
return [ $words, $stripped ];
}
/**
* @return string[]
*/
public function orig() {
$orig = new HWLDFWordAccumulator;
foreach ( $this->edits as $edit ) {
if ( $edit->type == 'copy' ) {
$orig->addWords( $edit->orig );
} elseif ( $edit->orig ) {
$orig->addWords( $edit->orig, 'del' );
}
}
$lines = $orig->getLines();
return $lines;
}
/**
* @return string[]
*/
public function closing() {
$closing = new HWLDFWordAccumulator;
foreach ( $this->edits as $edit ) {
if ( $edit->type == 'copy' ) {
$closing->addWords( $edit->closing );
} elseif ( $edit->closing ) {
$closing->addWords( $edit->closing, 'ins' );
}
}
$lines = $closing->getLines();
return $lines;
}
}