Text DIFF with highlighting

gistfile1.php

function htmlDiff($old, $new, $exceptions = array()) {
  $ret = '';
	$diff = diff(explode(' ', $old), explode(' ', $new), $exceptions);
	foreach ($diff as $k) {
		if (is_array($k)) {

			$ret .= (!empty($k['d']) ? "<del style='background:#FFFF00;'>" . implode(' ', $k['d']) . "</del> " : '') . (!empty($k['i']) ? "<ins style='background:#00FF00;'>" . implode(' ', $k['i']) . "</ins> " : '');
		}
		else {
			$ret .= $k . ' ';
		}
	}
	return $ret;
}

function diff($old, $new, $exceptions = array()) {
	$maxlen = 0;

	foreach ($old as $oindex => $ovalue) {
		$nkeys = array_keys($new, $ovalue);
		foreach ($nkeys as $nindex) {
			$matrix[$oindex][$nindex] = isset($matrix[$oindex - 1][$nindex - 1]) && in_array($ovalue, $exceptions) ? $matrix[$oindex - 1][$nindex - 1] + 1 : 1;
			if ($matrix[$oindex][$nindex] > $maxlen) {
				$maxlen = $matrix[$oindex][$nindex];
				$omax   = $oindex + 1 - $maxlen;
				$nmax   = $nindex + 1 - $maxlen;
			}
		}
	}

	if ($maxlen == 0) {
		return array(
			array(
				'd'=> $old,
				'i'=> $new
			)
		);
	}
	return array_merge(
		diff(array_slice($old, 0, $omax), array_slice($new, 0, $nmax)),
		array_slice($new, $nmax, $maxlen),
		diff(array_slice($old, $omax + $maxlen), array_slice($new, $nmax + $maxlen)));
}