php regular expression concatenation unwanted backslashes - php

Question

I'm trying to build a regular expression in php. I tested it here https://regex101.com/ and it works fine, but that was before I knew I'd have to implement it in php and it adds backslashes where not needed.
Here's my code:
$datePattern = "\[((19|20)\d\d)-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01])\]";
$tag = "[a-z]+(?:-[a-z]+)*";
$regroupmentPattern = "\[($tag)?\]";
$taglistPattern = "\[((?:$tag)?(?:;(?:$tag))*)\]";
$countryPattern = "\[([a-z]{2})\]";
$freePattern = "\[([^\[\]]*)\]";
$extensionPattern = "\.(jpg|png)";
$repetitionPattern = "(?:\(\d+\))?";
$fullPattern = "/^$datePattern$regroupmentPattern$taglistPattern$countryPattern$freePattern$freePattern$extensionPattern$repetitionPattern$/";
Here is what I want :
^\[((19|20)\d\d)-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01])\]\[([a-z]+(?:-[a-z]+)*)?\]\[((?:[a-z]+(?:-[a-z]+)*)?(?:;(?:[a-z]+(?:-[a-z]+)*))*)\]\[([a-z]{2})\]\[([^\[\]]*)\]\[([^\[\]]*)\](?:\(\d+\))?\.(jpg|png)$
And here's what I get :
"\"\\/^\\\\[((19|20)\\\\d\\\\d)-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01])\\\\]\\\\[([a-z]+(?:-[a-z]+)*)?\\\\]\\\\[((?:[a-z]+(?:-[a-z]+)*)?(?:;(?:[a-z]+(?:-[a-z]+)*))*)\\\\]\\\\[([a-z]{2})\\\\]\\\\[([^\\\\[\\\\]]*)\\\\]\\\\[([^\\\\[\\\\]]*)\\\\]\\\\.(jpg|png)(?:\\\\(\\\\d+\\\\))?$\\/\""
I assume there must be some sort of escape function, I tried preg_quote but it added yet even more backslashes.
Btw here's my full code:
<?php
class Gallery {
// Name of the gallery, used to build folder path
private $name;
function __construct($name) {
$this->name = $name;
}
/*
* Returns the list of file names in a gallery folder,
* or false if the folder doesn't exist
*/
public function getFileNames() {
$path = "../../gallery/$this->name";
if (is_dir($path)) {
$allFileNamesArray = scandir($path, SCANDIR_SORT_ASCENDING);
$filteredFileNamesArray = array();
// Building regular expression
$datePattern = "\[((19|20)\d\d)-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01])\]";
$tag = "[a-z]+(?:-[a-z]+)*";
$regroupmentPattern = "\[($tag)?\]";
$taglistPattern = "\[((?:$tag)?(?:;(?:$tag))*)\]";
$countryPattern = "\[([a-z]{2})\]";
$freePattern = "\[([^\[\]]*)\]";
$extensionPattern = "\.(jpg|png)";
$repetitionPattern = "(?:\(\d+\))?";
$fullPattern = "/^$datePattern$regroupmentPattern$taglistPattern$countryPattern$freePattern$freePattern$extensionPattern$repetitionPattern$/";
foreach ($allFileNamesArray as $fileName) {
$matches = array();
if (preg_match($fullPattern, $fileName, $matches, PREG_UNMATCHED_AS_NULL)) {
$filteredFileNamesArray[] = $fileName;
}
var_dump($matches);
}
return json_encode($fullPattern);
}
else {
return false;
}
}
}
?>
(Here I returned fullPattern istead of filteredFileNamesArray for debugging purpose)

Answer 1

You swapped $repetitionPattern and $extensionPattern.
Use
$fullPattern = "/^$datePattern$regroupmentPattern$taglistPattern$countryPattern$freePattern$freePattern$repetitionPattern$extensionPattern$/";
It will result in
^\[((19|20)\d\d)-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01])\]\[([a-z]+(?:-[a-z]+)*)?\]\[((?:[a-z]+(?:-[a-z]+)*)?(?:;(?:[a-z]+(?:-[a-z]+)*))*)\]\[([a-z]{2})\]\[([^\[\]]*)\]\[([^\[\]]*)\](?:\(\d+\))?\.(jpg|png)$ pattern.
See the regex demo online.