PHP Regex create something like liquid tags

Question

I'm trying to parse something like this

{%github user/repo %}

Into

<a href="https://github.com/user/repo">Repo</a>

This method also should be secure ex: Look below my function.

function parseliquid($string)
{
    $randhashtoreplace = md5(rand(0, 9999));
    $regexp = '/\{%github (.*?)%\}/';
    $str = preg_replace($regexp, $randhashtoreplace, $string);

    preg_match($regexp, $string, $matches);
    return $matches;
}


var_dump(parseliquid("## Hello {%github isn't/safe {%github repo/user %} %}"));

Now the expected output is

array(2) {
  [0]=>
  string(41) "{%github isn't/safe {%github repo/user %}"
  [1]=>
  string(9) "repo/user"
}

but the output that comes is

array(2) {
  [0]=>
  string(41) "{%github isn't/safe {%github repo/user %}"
  [1]=>
  string(30) "isn't/safe {%github repo/user "
}

Now what have I done wrong?

"Now what have I done wrong?" choosing regular expression to parse nested expressions (they aren't suited for that, see the regex HTML or JSON parsing problems). You need to either write a proper parser or use an existing one — Cid
– Cid, Commented Nov 12, 2021 at 10:36
I'm sure if you type in your favorite search engine "liquid php parser", you'll find lots of packages — Cid
– Cid, Commented Nov 12, 2021 at 10:40

OlehTytarenko · Accepted Answer · 2021-11-12 10:57:04Z

1

You can try this code

<?php

function getRepositoryNames(string $value): array
{
    \preg_match_all('/\{\%github\s(?<repo>[a-z0-9-_]+\/[a-z0-9-_]+)\s+/', $value, $matched);

    if (!isset($matched['repo'])) {
        return [];
    }

    return \array_map(static fn ($item) => 'https://github.com/'.$item, $matched['repo']);
}

\var_dump(getRepositoryNames('{%github isnt/safe {%github repo/user1-test %}'));
/*
 array(2) {
  [0]=>
  string(28) "https://github.com/isnt/safe"
  [1]=>
  string(34) "https://github.com/repo/user1-test"
}
 */

Documentation:

https://www.php.net/manual/en/function.preg-match.php - Use Example #4

Tested Regex you can this https://regexr.com/

edited Nov 12, 2021 at 10:57

answered Nov 12, 2021 at 10:47

OlehTytarenko

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3 Comments

Posandu Over a year ago

Thank you! and why did you use \ s?

OlehTytarenko Over a year ago

\s it's short from space If you use \s regex try find one space ` ` another \s+ one or more spaces

OlehTytarenko Over a year ago

@ŕ̷͉ge̸ḓ̶̅i̷t regex-cheatsheet

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