我可以以某种方式知道在preg_replace_callback的回调中发生了哪些替换？

Question

I'm using preg_replace_callback to substitute particular tokens within the string. But apart from actual token I need to know as well whether that token was first, second or third in a subject string. Is there any way to access that info?

I found an argument $count in preg_replace_callback definition (http://php.net/manual/en/function.preg-replace-callback.php), which counts replacements, but I'm not sure if it is accessible from within callback. Any example of the usage in described context?

Answer 1

The $count out variable is only set after all the replacements are done. Instead, try a static variable:

function repl($matches) {
    static $count = 0;
    ++$count;
    ...
}
preg_replace_callback('/.../', 'repl', $haystack);