需要帮助优化php字符串差异功能

Question

I created this function and it works on small strings, but for longer strings it times-out. I'm looking for a way to make the function work faster and not timeout, or a better way to accomplish what I want.

function find_diffs($string1, $string2)
{
    $array1 = preg_split("/\b/", $string1);
    $array2 = preg_split("/\b/", $string2);
    $array3 = array();


    for($i=0, $j=0; $i < count($array1) || $j < count($array2); $i++, $j++)
    {
        while(badchars($array1, $i))
        {
            $i++;
        }
        while(badchars($array2, $j))
        {
            $j++;
        }

        if($array1[$i] != $array2[$j])
        {
            //-------------------------Find Subtractions--------------------//
            $k = $i;
            while($array1[$i] != $array2[$j])
            {
                $i++;
                if($i == count($array1))
                {
                    $end = true;
                    break;
                }
                while(badchars($array1, $i))
                {
                    $i++;
                }
            }
            if($end)
            {
                //-------------------------Find Additions--------------------//
                $end = false;
                $i = $k;
                $k = $j;
                while($array1[$i] != $array2[$j])
                {
                    $j++;
                    if($j == count($array2))
                    {
                        $end = true;
                        break;
                    }
                    while(badchars($array2, $j))
                    {
                        $j++;
                    }
                }
                if($end)
                {
                    //-------------------------Find Changes--------------------//
                    $end = false;
                    $j = $k;
                    $l = $i;
                    while($array1[$i] != $array2[$j])
                    {

                        $k = $j;
                        while($array1[$i] != $array2[$j])
                        {
                            $j++;
                            if($j == count($array2))
                            {
                                $end = true;
                                break;
                            }
                            while(badchars($array2, $j))
                            {
                                $j++;
                            }
                        }

                        if($end)
                        {
                            $j = $k;
                            $i++;
                            while(badchars($array1, $i))
                            {
                                $i++;
                            }
                            while(badchars($array2, $j))
                            {
                                $j++;
                            }
                        }
                        else
                        {
                            $array3[] = array($l,$i,'-');
                            $array3[] = array($k,$j,'+');
                        }
                        if($i == count($array1))
                        {
                            $end = true;
                            break;
                        }
                        if($j == count($array2))
                        {
                            $end = true;
                            break;
                        }
                        $end=false;
                    }
                    if($end)
                    {
                            break;          
                    }
                    else
                    {
                        $array3[] = array($l,$i,'-');
                        $array3[] = array($k,$j,'+');
                    }   
                    //---------------------End Find Changes--------------------//
                }
                else
                {
                    $array3[] = array($k,$j,'+');
                }
            }
            else
            {
                $array3[] = array($k,$i,'-');
            }

        }
    }

    $array3[] = array(0,count($array1),'=');
    return array($array1,$array2,$array3);
}

Answer 1

Don't reinvent the wheel. This is the sort of thing that is easy to get wrong and hard to get right.

Check out the Text_Diff Pear Package. I have used it for this sort of thing and it is very well done.