Replace AMP binding attributes with ones that can be parsed in PHP

includes/utils/class-amp-dom-utils.php

@@ -56,6 +56,18 @@ public static function get_dom( $document ) {
 
 		$dom = new DOMDocument();
 
+		// Replace AMP binding attributes with something that libxml can parse (as HTML5 data-* attributes).
+		$document = preg_replace_callback(
+			// Match all start tags that contain a binding attribute.
+			'#<(?P<tag>\w\S+)(?P<attrs>\s+[^<]+\]=[^<]+)\s*>#',
+			function( $matches ) {
+				$attrs = preg_replace( '/\s\[([a-z0-9_\-]+)\]=/i', ' data-amp-binding---$1=', $matches['attrs'] );
+				// @todo What if someone does data-foo=" [text]='somthing bad' "?
+				return '<' . $matches['tag'] . $attrs . '>';
+			},
+			$document
+		);
+
 		/*
 		 * Wrap in dummy tags, since XML needs one parent node.
 		 * It also makes it easier to loop through nodes.