1--TEST--
2preg_replace_callback()
3--FILE--
4<?php
5$input = "plain [indent] deep [indent] [abcd]deeper[/abcd] [/indent] deep [/indent] plain";
6
7function parseTagsRecursive($input)
8{
9
10    $regex = '#\[indent]((?:[^[]|\[(?!/?indent])|(?R))+)\[/indent]#';
11
12    if (is_array($input)) {
13        $input = '<div style="margin-left: 10px">'.$input[1].'</div>';
14    }
15
16    return preg_replace_callback($regex, 'parseTagsRecursive', $input);
17}
18
19$output = parseTagsRecursive($input);
20
21echo $output, "\n";
22
23?>
24--EXPECT--
25plain <div style="margin-left: 10px"> deep <div style="margin-left: 10px"> [abcd]deeper[/abcd] </div> deep </div> plain
26