<?php
$re = '~\s*("[^"\\\\]*(?:\\\\.[^\\\\"]*)*"|\'[^\'\\\\]*(?:\\\\.[^\\\\\']*)*\'|[^,]+),?~';
$str = "\"test\", 'test2', \$test3, ?\"%A %d %B %Y\", \"foo,bar,foobar\"";
PD9waHAKCiRyZSA9ICd+XHMqKCJbXiJcXFxcXSooPzpcXFxcLlteXFxcXCJdKikqInxcJ1teXCdcXFxcXSooPzpcXFxcLlteXFxcXFwnXSopKlwnfFteLF0rKSw/fic7IAokc3RyID0gIlwidGVzdFwiLCAndGVzdDInLCBcJHRlc3QzLCA/XCIlQSAlZCAlQiAlWVwiLCBcImZvbyxiYXIsZm9vYmFyXCIiOyAKcHJlZ19tYXRjaF9hbGwoJHJlLCAkc3RyLCAkdG9rZW5zKTsKcHJpbnRfcigkdG9rZW5zWzFdKTs=