When I was setting up this website, I foolishly picked a custom log file format that is rather hard for computers to parse. Because of this I haven't found a server log analysis tool that is intelligent enough to parse my logs (if you know of one please let me know in the comments!).

Here is an example of a typical log file entry:

[19/May/2015:00:47:52 +0100] "starbeamrainbowlabs.com" HTTP/1.1 GET 200 162.243.87.220 0s :443 /blog/article.php article=posts/013-Terminal-Reference.html "https://starbeamrainbowlabs.com/blog/?offset=60" "Mozilla/5.0 (compatible; spbot/4.4.2; +http://OpenLinkProfiler.org/bot )"

It looks strange, doesn't it? Since I want to have some idea of how many people are visiting my site, I have finally gotten around to writing my own custom log parser. In order to do this, I needed a way to convert each line into an array of terms. None of the answers on stackoverflow seemed to cut it, so I wrote my own:

<?php
function explode_adv($openers, $closers, $togglers, $delimiters, $str)
{
    $chars = str_split($str);
    $parts = [];
    $nextpart = "";
    $toggle_states = array_fill_keys($togglers, false); // true = now inside, false = now outside
    $depth = 0;
    foreach($chars as $char)
    {
        if(in_array($char, $openers))
            $depth++;
        elseif(in_array($char, $closers))
            $depth--;
        elseif(in_array($char, $togglers))
        {
            if($toggle_states[$char])
                $depth--; // we are inside a toggle block, leave it and decrease the depth
            else
                // we are outside a toggle block, enter it and increase the depth
                $depth++;

            // invert the toggle block state
            $toggle_states[$char] = !$toggle_states[$char];
        }
        else
            $nextpart .= $char;

        if($depth < 0) $depth = 0;

        if(in_array($char, $delimiters) &&
           $depth == 0 &&
           !in_array($char, $closers))
        {
            $parts[] = substr($nextpart, 0, -1);
            $nextpart = "";
        }
    }
    if(strlen($nextpart) > 0)
        $parts[] = $nextpart;

    return $parts;
}
?>

I have also posted this on stackoverflow. This function of mine takes 5 parameters:

1. An array of characters that open a block - e.g. [, (, etc.
2. An array of characters that close a block - e.g. ], ), etc.
3. An array of characters that toggle a block - e.g. ", ', etc.
4. An array of characters that should cause a split into the next part.
5. The string to work on.

This function probably will have flaws, but it works well enough for me.

You can also find this function on GitHub's Gist - as always suggestions and contributions are always welcome :)