<?php
/**
*
* Class \webdof\Text\diff\Compare
*
* Compares two texts, finds the diffrences and patches back to
* the original version using a minimal ammount of data.
*
* Version: 4.0.0
*
* @Author: Till Wehowski, http://www.webfan.de
* @Author: php Community, http://php.net
* @License: Do What The Fuck You Want To Public License
*
* http://www.phpclasses.org/package/8834-PHP-Class-to-find-differences-in-texts-and-rollback.html
*
* */
namespace webdof\Text\diff;
/**
* Example:
$text_1 = 'Dies ist ein Test uber Hackfleisch.<br />Dies ist ein Text uber Hackfleisch.';
$text_2 = "Dies ist Text uber Kackfleisch.<br />Dies ist Test uber Kackfleisch.";
$newversion = $text_2;
$comp = new \webdof\Text\diff\Compare();
$diff = $comp->calcdiffer($text_1, $text_2);
echo $text_1.'<br />';
echo $text_2.'<br />';
echo '<pre>'.print_r($diff, true).'</pre>';
$back = '';
foreach( $diff as $step => $d)
{
if($d[0] === '=' || $d[0] === '-')$back.= $d[1];
}
echo 'Patching:<br />';
echo $back.'<br />';
echo '<br />';
echo 'Patching Rüwärts nur mit Änderungen und strlen(equals):<br />';
$diff = $comp->minimize( $diff );
$oldversion = $comp->patch( $text_2, $diff );
echo '<pre>'.print_r($diff, true).'</pre>';
echo $oldversion.'<br />';
echo '<br /><br />Test 2<br />';
$text_1 = 'An einem Sommertag fuhr ich mit dem Fahrrad über die Straße nach Hause.';
$text_2 = 'An einem schönen Sommertag ging ich mit dem Auto über die Straße spazieren.';
echo $text_1.'<br />';
echo $text_2.'<br />';
$comp = new \webdof\Text\diff\Compare();
$diff = $comp->calcdiffer($text_1, $text_2);
$diff = $comp->minimize( $diff );
$oldversion = $comp->patch( $text_2, $diff );
echo $oldversion.'<br />';
*
*/
class Compare
{
const ADD = 0; // = '+';
const DEL = 1; // = '-';
const EQUAL = 2; // = '=';
protected $data = array(
'old' => NULL,
'version' => array(
'new' => NULL,
'diff' => NULL,
),
);
function __construct($old = NULL, $new = NULL)
{
if(is_string($old) && is_string($new))return $this->diff($old, $new);
}
public function data($data = NULL) {
if(is_array($data) && (isset($data['old']) || isset($data['version'])))$this->data = $data;
return $this->data;
}
public function diff($old, $new, $returns = 'version'){
$this->data = array(
'old' => $old,
'version' => array(
'new' => $new,
'diff' => $this->minimize( $this->calcdiffer($old, $new) ),
),
);
switch($returns){
case 'version' :
$result = $this->data['version'];
break;
case 'minimized' :
case 'diff' :
$result = $this->data['version']['diff'];
break;
case 'all' :
case 'max' :
$this->data['sha1'] = array(
'old' => sha1($old),
'new' => sha1($new),
);
$this->data['strlen'] = array(
'old' => strlen($old),
'new' => strlen($new),
);
$result = $this->data;
break;
case 'data' :
default :
$result = $this->data;
break;
}
return $result;
}
/*
* Alias for patch
* */
public function rollback($newversion, $diff)
{
return $this->patch($newversion, $diff);
}
public function patch($newversion, $diff)
{
$back = array_reverse($diff);
$str = '';
$r = strrev($newversion);
$offset = 0;
foreach($back as $step => $d)
{
if($d[0] === self::DEL)$d[1] = strrev($d[1]);
if($d[0] === self::EQUAL)$str.= substr($r, $offset, $d[2] );
if($d[0] === self::DEL)$str.= $d[1];
if($d[0] === self::ADD || $d[0] === self::EQUAL)$offset += $d[2];
}
$oldversion = strrev($str);
return $oldversion;
}
/*
*
* minimize
* compress the diff data, we only need the the added and equal strings position and length
* and the value of the deleted strings
*
*/
public function minimize($diff)
{
foreach($diff as $step => $d)
{
if($diff[$step][0] !== self::DEL)$diff[$step][1] = NULL;
}
return $diff;
}
/*
* Returns the differences of $a and $b
*/
public function calcdiffer($a, $b)
{
$alen = strlen($a);
$blen = strlen($b);
$aptr = 0;
$bptr = 0;
$ops = array();
while($aptr < $alen && $bptr < $blen)
{
$matchlen = $this->matchlen(substr($a, $aptr), substr($b, $bptr));
if($matchlen)
{
$str = substr($a, $aptr, $matchlen);
$ops[] = array(self::EQUAL, $str, strlen($str) );
$aptr += $matchlen;
$bptr += $matchlen;
continue;
}
/* Difference found */
$bestlen=0;
$bestpos=array(0,0);
for($atmp = $aptr; $atmp < $alen; $atmp++)
{
for($btmp = $bptr; $btmp < $blen; $btmp++)
{
$matchlen = $this->matchlen(substr($a, $atmp), substr($b, $btmp));
if($matchlen>$bestlen)
{
$bestlen=$matchlen;
$bestpos=array($atmp,$btmp);
}
if($matchlen >= $blen-$btmp)break;
}
}
if(!$bestlen)break;
$adifflen = $bestpos[0] - $aptr;
$bdifflen = $bestpos[1] - $bptr;
if($adifflen)
{
$str = substr($a, $aptr, $adifflen);
$ops[] = array(self::DEL, $str, strlen($str) );
$aptr += $adifflen;
}
if($bdifflen)
{
$str = substr($b, $bptr, $bdifflen);
$ops[] = array(self::ADD, $str, strlen($str) );
$bptr += $bdifflen;
}
$str = substr($a, $aptr, $bestlen);
$ops[] = array(self::EQUAL, $str, strlen($str) );
$aptr += $bestlen;
$bptr += $bestlen;
}
if($aptr < $alen)
{
/* b has too much stuff */
$str = substr($a, $aptr);
$ops[] = array(self::DEL, $str, strlen($str) );
}
if($bptr < $blen)
{
/* a has too little stuff */
$str = substr($b, $bptr);
$ops[] = array(self::ADD, $str, strlen($str) );
}
return $ops;
}
protected function matchlen(&$a, &$b)
{
$c=0;
$alen = strlen($a);
$blen = strlen($b);
$d = min($alen, $blen);
while($a[$c] == $b[$c] && $c < $d)
$c++;
return $c;
}
}
//eof
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