From e920d879282acde53eef26957f39d09524c47410 Mon Sep 17 00:00:00 2001
From: Weston Ruter <westonruter@google.com>
Date: Wed, 15 May 2019 17:05:07 -0700
Subject: [PATCH] Account for toggleClass when obtaining used class names for
 tree shaking

---
 .../sanitizers/class-amp-style-sanitizer.php  | 15 ++++++++++++
 tests/test-amp-style-sanitizer.php            | 24 +++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/includes/sanitizers/class-amp-style-sanitizer.php b/includes/sanitizers/class-amp-style-sanitizer.php
index 5fb9c704241..1691e3fd4a3 100644
--- a/includes/sanitizers/class-amp-style-sanitizer.php
+++ b/includes/sanitizers/class-amp-style-sanitizer.php
@@ -450,6 +450,21 @@ private function get_used_class_names() {
 			array_unique( array_filter( preg_split( '/\s+/', trim( $classes ) ) ) )
 		);
 
+		// Find all instances of the toggleClass() action to prevent the class name from being tree-shaken.
+		foreach ( $this->xpath->query( '//*/@on[ contains( ., "toggleClass" ) ]' ) as $on_attribute ) {
+			if ( preg_match_all( '/\.\s*toggleClass\s*\(\s*class\s*=\s*(([\'"])([^\1]*?)\2|[a-zA-Z0-9_\-]+)/', $on_attribute->nodeValue, $matches ) ) {
+				$class_names = array_merge(
+					$class_names,
+					array_map(
+						function ( $match ) {
+							return trim( $match, '"\'' );
+						},
+						$matches[1]
+					)
+				);
+			}
+		}
+
 		$this->used_class_names = array_fill_keys( $class_names, true );
 		return $this->used_class_names;
 	}
diff --git a/tests/test-amp-style-sanitizer.php b/tests/test-amp-style-sanitizer.php
index fb24a5f145d..19f2cedc460 100644
--- a/tests/test-amp-style-sanitizer.php
+++ b/tests/test-amp-style-sanitizer.php
@@ -757,6 +757,30 @@ public function get_attribute_selector_data() {
 					'.\@\@\@\@'         => false,
 				),
 			),
+			'toggle_class' => array(
+				implode(
+					'',
+					array(
+						'<div id=\"foo\"></div>',
+						'<button on="tap:foo . toggleClass ( class = \'expanded\' )">Yes</button>',
+						'<button on="tap:foo.toggleClass(class=\'clicked\')">Yes</button>',
+						'<button on="tap:foo.toggleClass(class=&quot;tapped&quot;)">Yes</button>',
+						'<button on="tap:foo.toggleClass(class=pressed);tap:foo.toggleClass(class = im-pressed)">Yes</button>',
+						'<button on="tap:foo.toggleClass(class = \'touch:ed\' )">Yes</button>',
+						'<button on="tap:AMP.setState({toggleClass:\'stateful\'})">No</button>',
+					)
+				),
+				array(
+					'.expanded'   => true,
+					'.clicked'    => true,
+					'.tapped'     => true,
+					'.pressed'    => true,
+					'.im-pressed' => true,
+					'.touch\:ed'  => true,
+					'.exploded'   => false,
+					'.stateful'   => false,
+				),
+			),
 		);
 	}