Converting string but leave characters wrapped in braces

Question

1. I'm converting a user input string (successfully but...)
2. I would like to ignore characters wrapped in braces
3. Also remove the braces in the final output

So for instance if I have this string:

$string = "[ABC] This & Text";

function make_post_type($string) {
  $needle   = array('-', ' ');
  $clean    = preg_replace("/[^a-zA-Z0-9_\s]/", "", strtolower($string)); // Remove special characters
  $haystack = preg_replace('!\s+!', ' ', $clean); // Now remove extra spaces

  return str_replace($needle, '_', $haystack);
}

returns abc_this_text

I would like to return ABC_this_text

Answer 1

You may use this regex code in preg_replace_callback:

function replc($str) {
   return preg_replace_callback (
      '/\[([^]]*)\]|{([^}]*)}|([^][{}]+)/',
      function ($m) {
         return (isset($m[1])?$m[1]:"") .
                (isset($m[2])?$m[2]:"") .
                 (isset($m[3]) ?
                 preg_replace('/\W+/', '_', strtolower($m[3])) : "");
      },
      $str
   );
}

Call it as:

echo replc( "[ABC] This & Text" );
ABC_this_text

echo replc( "abc.Xyz {PQR} Foo-Bar [ABC] This & Text" );
abc_xyz_PQR_foo_bar_ABC_this_text

1st RegEx Details:

• [([^]]*)\]: If we encounter [...] then capture inner part in group #1
• |: OR
• {([^}]*)}: If we encounter {...} then capture inner part in group #2
• |: OR
• [^][{}]+: Match 1+ character that is not [ and ] and { and } and capture in group #3

2nd RegEx:

• \W+: match 1+ non-word character to be replaced by _