Parse string based on pattern - php

Question

I am using php 5 to parse a string. My input string looks like the following:
{Billion is|Millions are|Trillion is} {an extremely |a| a generously |
a very} { tiny|little |smallish |short |small} stage in a vast
{galactic| |large|huge|tense|big |cosmic}
{universe|Colosseum|planet|arena}.
Find below my minimum viable example:
<?php
function process($text)
{
return preg_replace_callback('/\[(((?>[^\[\]]+)|(?R))*)\]/x', array(
$this,
'replace'
), $text);
}
function replace($text)
{
$text = $this->process($text[1]);
$parts = explode('|', $text);
return $parts[array_rand($parts)];
}
$text = "{Billion is|Millions are|Trillion is} {an extremely |a| a generously | a very} { tiny|little |smallish |short |small} stage in a vast {galactic| |large|huge|tense|big |cosmic} {universe|Colosseum|planet|arena}.";
$res = process($text);
echo $res;
As you can see I am trying to parse the following pattern f.ex.: {Billion is|Millions are|Trillion is} using the above regex, /\[(((?>[^\[\]]+)|(?R))*)\]/x.
As a result I am getting the same string as inputted. I would like to get as an output for example:
Billion is a very little stage in a vast huge arena.
Any suggestions what I am doing wrong?

Answer 1

How would your current code generate anything.
Your regex doesn't fit. It matches nested bracketed stuff and not braced. Try{([^}]*)} for capturing everything inside {...} to $m[1] if there are no nested braces.
Read about preg_replace_callback(). The second argument can not be an array.
A working code with some further adjustments could look like this:
function process($text) {
return preg_replace_callback('/{([^}]*)}/', 'replace', $text);
}
function replace($m) {
$parts = explode('|', $m[1]);
shuffle($parts);
return $parts[0];
}
$text = "{Billion is|Millions are|Trillion is} {an extremely|a|a generously|a very} {tiny|little|smallish|short|small} stage in a vast {galactic||large|huge|tense|big|cosmic} {universe|Colosseum|planet|arena}.";
echo process($text);
Billion is a generously short stage in a vast Colosseum.
Here is a demo at eval.in
(you can also use an anonymous function if PHP >= 5.3)