Merge pull request #22 from psu-libraries/21-add-twig-filter-to-remove-html-comments

Issue #21 - Add twig filter to strip comments from HTML.

Author: zipymonkey

psulib_base_helper.services.yml

@@ -0,0 +1,5 @@
+services:
+  psulib_base_helper.remove_html_comments:
+    class: Drupal\psulib_base_helper\TwigExtension\StripHtmlComments
+    tags:
+      - { name: twig.extension }

src/TwigExtension/StripHtmlComments.php

@@ -0,0 +1,92 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\psulib_base_helper\TwigExtension;
+
+use Twig\Extension\AbstractExtension;
+use Twig\TwigFilter;
+
+/**
+ * Provides a Twig filter that strips HTML comments from input.
+ *
+ * @package Drupal\psulib_base_helper\TwigExtension
+ */
+class StripHtmlComments extends AbstractExtension {
+
+  /**
+   * Generates a list of all Twig filters that this extension defines.
+   *
+   * @return array
+   *   The Twig filters of this extension.
+   */
+  public function getFilters(): array {
+    return [
+      new TwigFilter('strip_html_comments', [
+        $this,
+        'stripHtmlCommentsFromString'
+      ]),
+      new TwigFilter('strip_html_comments_render', [
+        $this,
+        'stripHtmlCommentsAsRenderArray'
+      ]),
+    ];
+  }
+
+  /**
+   * Gets the unique identifier for this Twig extension.
+   *
+   * @return string
+   *   The identifier for this extension.
+   */
+  public function getName(): string {
+    return 'psulib_base_helper.strip_html_comments';
+  }
+
+  /**
+   * Strips HTML comments from string.
+   *
+   * Example: A string which has value <!--Start DEBUG--> ABCD <!--End DEBUG-->
+   * will be returned the output ABCD after using the the following function.
+   *
+   * @param string|null $string
+   *   A string or NULL.
+   *
+   * @return array
+   *   The string as markup render array without HTML comments.
+   */
+  public function stripHtmlCommentsAsRenderArray(?string $string): array {
+    if ($string !== NULL) {
+      $stringWithoutHtmlComments = $this->stripHtmlCommentsFromString($string);
+    }
+    else {
+      $stringWithoutHtmlComments = '';
+    }
+
+    return [
+      '#markup' => $stringWithoutHtmlComments,
+    ];
+  }
+
+  /**
+   * Strips HTML comments from string.
+   *
+   * Example: A string which has value <!--Start DEBUG--> ABCD <!--End DEBUG-->
+   * will be returned the output ABCD after using the the following function.
+   *
+   * @param string|null $string
+   *   A string or NULL.
+   *
+   * @return string
+   *   The string without HTML comments.
+   */
+  public function stripHtmlCommentsFromString(?string $string): string {
+    if ($string !== NULL) {
+      return preg_replace('/<!--(.|\s)*?-->\s*|\r|\n/', '', $string);
+    }
+    else {
+      return '';
+    }
+  }
+
+}