55 lines
1.7 KiB
PHP
55 lines
1.7 KiB
PHP
<?php
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/*
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Paul's Simple Diff Algorithm v 0.1
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(C) Paul Butler 2007 <http://www.paulbutler.org/>
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May be used and distributed under the zlib/libpng license.
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This code is intended for learning purposes; it was written with short
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code taking priority over performance. It could be used in a practical
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application, but there are a few ways it could be optimized.
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Given two arrays, the function diff will return an array of the changes.
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I won't describe the format of the array, but it will be obvious
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if you use print_r() on the result of a diff on some test data.
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htmlDiff is a wrapper for the diff command, it takes two strings and
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returns the differences in HTML. The tags used are <ins> and <del>,
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which can easily be styled with CSS.
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*/
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function diff($old, $new){
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$maxlen = 0;
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foreach($old as $oindex => $ovalue){
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$nkeys = array_keys($new, $ovalue);
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foreach($nkeys as $nindex){
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$matrix[$oindex][$nindex] = isset($matrix[$oindex - 1][$nindex - 1]) ?
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$matrix[$oindex - 1][$nindex - 1] + 1 : 1;
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if($matrix[$oindex][$nindex] > $maxlen){
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$maxlen = $matrix[$oindex][$nindex];
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$omax = $oindex + 1 - $maxlen;
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$nmax = $nindex + 1 - $maxlen;
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}
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}
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}
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if($maxlen == 0) return array(array('d'=>$old, 'i'=>$new));
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return array_merge(
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diff(array_slice($old, 0, $omax), array_slice($new, 0, $nmax)),
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array_slice($new, $nmax, $maxlen),
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diff(array_slice($old, $omax + $maxlen), array_slice($new, $nmax + $maxlen)));
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}
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function htmlDiff($old, $new){
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$ret = '';
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$diff = diff(explode(' ', $old), explode(' ', $new));
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foreach($diff as $k){
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if(is_array($k))
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$ret .= (!empty($k['d'])?"<del>".implode(' ',$k['d'])."</del> ":'').
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(!empty($k['i'])?"<ins>".implode(' ',$k['i'])."</ins> ":'');
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else $ret .= $k . ' ';
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}
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return $ret;
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}
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?>
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