From bdb8821a11f2fb07402c5d05055c6eae91244529 Mon Sep 17 00:00:00 2001
From: RedLucas <RedLucas@users.noreply.github.com>
Date: Mon, 10 Jul 2017 17:12:53 -0700
Subject: [PATCH] Make the clean_class filter act like Drupal one.

I would feel more comfortable using the clean_class filter in my pattern-lab templates if I was confident it would do the same in Pattern Lab as it does in Drupal.
---
 dist/filters/clean_class.filter.php | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/dist/filters/clean_class.filter.php b/dist/filters/clean_class.filter.php
index 7dcda24..3f0f83b 100755
--- a/dist/filters/clean_class.filter.php
+++ b/dist/filters/clean_class.filter.php
@@ -1,5 +1,18 @@
 <?php
 
 $filter = new Twig_SimpleFilter('clean_class', function ($string) {
+  $filters = [
+    ' ' => '-',
+    '_' => '-',
+    '/' => '-',
+    '[' => '-',
+    ']' => '',
+  ];
+  $string = str_replace(array_keys($filters), array_values($filters), $string);
+  $string = preg_replace('/[^\x{002D}\x{0030}-\x{0039}\x{0041}-\x{005A}\x{005F}\x{0061}-\x{007A}\x{00A1}-\x{FFFF}]/u', '', $string);
+  $string = preg_replace([
+    '/^[0-9]/',
+    '/^(-[0-9])|^(--)/'
+  ], ['_', '__'], $string);
   return $string;
 });