/**
* calculate the difference between 2 strings
*
* @param string $a
* @param string $b
* @param float $divisor for calculating the minimum required percentage of overlap
* @return string a merged version of $a and $b, with deleted and inserted
* portions indicated by <del></del> and <ins></ins> tags
*/
public static function diff($a, $b, $divisor = 3.0)
{
self::$divisor = $divisor;
if ($a == $b) {
return $a;
} elseif (empty($a)) {
return '<ins>' . $b . '</ins>';
} elseif (empty($b)) {
return '<del>' . $a . '</del>';
}
$lcs = StringDiff::longest_common_substring($a, $b);
if (empty($lcs)) {
return '<del>' . $a . '</del><ins>' . $b . '</ins>';
}
$atripartite = StringDiff::tripartite($a, $lcs);
$btripartite = StringDiff::tripartite($b, $lcs);
$headdiff = StringDiff::diff($atripartite[0], $btripartite[0]);
$taildiff = StringDiff::diff($atripartite[2], $btripartite[2]);
return $headdiff . $lcs . $taildiff;
}
