An explode() function that ignores characters inside quotes?

Question

Does somebody know a quick and easy explode() like function that can ignore splitter characters that are enclosed in a pair of arbitrary characters (e.g. quotes

Answer 1

This is near-impossible with preg_split, because you can't tell from the middle of the string whether you're between quotes or not. However, preg_match_all can do the job.

Simple solution for a single type of quote:

function quoted_explode($subject, $delimiter = ',', $quote = '\'') {
    $regex = "(?:[^$delimiter$quote]|[$quote][^$quote]*[$quote])+";
    preg_match_all('/'.str_replace('/', '\\/', $regex).'/', $subject, $matches);
    return $matches[0];
}

That function will have all kinds of problems if you pass it certain special characters (\^-], according to http://www.regular-expressions.info/reference.html), so you'll need to escape those. Here's a general solution that escapes special regex characters and can track multiple kinds of quotes separately:

function regex_escape($subject) {
    return str_replace(array('\\', '^', '-', ']'), array('\\\\', '\\^', '\\-', '\\]'), $subject);
}

function quoted_explode($subject, $delimiters = ',', $quotes = '\'') {
    $clauses[] = '[^'.regex_escape($delimiters.$quotes).']';
    foreach(str_split($quotes) as $quote) {
        $quote = regex_escape($quote);
        $clauses[] = "[$quote][^$quote]*[$quote]";
    }
    $regex = '(?:'.implode('|', $clauses).')+';
    preg_match_all('/'.str_replace('/', '\\/', $regex).'/', $subject, $matches);
    return $matches[0];
}

(Note that I keep all of the variables between square brackets to minimize what needs escaping - outside of square brackets, there are about twice as many special characters.)

If you wanted to use ] as a quote, then you probably wanted to use [ as the corresponding quote, but I'll leave adding that functionality as an exercise for the reader. :)