true, ]; /** * Tag. * * @var string HTML tag to identify and replace with AMP version. */ public static $tag = 'meta'; /* * Tags array keys. */ const TAG_CHARSET = 'charset'; const TAG_HTTP_EQUIV = 'http-equiv'; const TAG_VIEWPORT = 'viewport'; const TAG_AMP_SCRIPT_SRC = 'amp_script_src'; const TAG_OTHER = 'other'; /** * Associative array of DOMElement arrays. * * Each key in the root level defines one group of meta tags to process. * * @var array $tags { * An array of meta tag groupings. * * @type DOMElement[] $charset Charset meta tag(s). * @type DOMElement[] $viewport Viewport meta tag(s). * @type DOMElement[] $amp_script_src source meta tags. * @type DOMElement[] $other Remaining meta tags. * } */ protected $meta_tags = [ self::TAG_CHARSET => [], self::TAG_HTTP_EQUIV => [], self::TAG_VIEWPORT => [], self::TAG_AMP_SCRIPT_SRC => [], self::TAG_OTHER => [], ]; /** * Viewport settings to use for AMP markup. * * @var string */ const AMP_VIEWPORT = 'width=device-width'; /** * Spec name for the tag spec for meta elements that are allowed in the body. * * @since 1.5.2 * @var string */ const BODY_ANCESTOR_META_TAG_SPEC_NAME = 'meta name= and content='; /** * Get tag spec for meta tags which are allowed in the body. * * @since 1.5.2 * @return string Deny pattern. */ private function get_body_meta_tag_name_attribute_deny_pattern() { static $pattern = null; if ( null === $pattern ) { $tag_spec = current( array_filter( AMP_Allowed_Tags_Generated::get_allowed_tag( 'meta' ), static function ( $spec ) { return isset( $spec['tag_spec']['spec_name'] ) && self::BODY_ANCESTOR_META_TAG_SPEC_NAME === $spec['tag_spec']['spec_name']; } ) ); $pattern = '/' . $tag_spec['attr_spec_list']['name']['disallowed_value_regex'] . '/'; } return $pattern; } /** * Sanitize. */ public function sanitize() { $meta_elements = iterator_to_array( $this->dom->getElementsByTagName( static::$tag ), false ); foreach ( $meta_elements as $meta_element ) { // Strip whitespace around equal signs. Won't be needed after is resolved. if ( $meta_element->hasAttribute( Attribute::CONTENT ) ) { $meta_element->setAttribute( Attribute::CONTENT, preg_replace( '/\s*=\s*/', '=', $meta_element->getAttribute( Attribute::CONTENT ) ) ); } /** * Meta tag to process. * * @var DOMElement $meta_element */ if ( $meta_element->hasAttribute( Attribute::CHARSET ) ) { $this->meta_tags[ self::TAG_CHARSET ][] = $meta_element->parentNode->removeChild( $meta_element ); } elseif ( $meta_element->hasAttribute( Attribute::HTTP_EQUIV ) ) { $this->meta_tags[ self::TAG_HTTP_EQUIV ][] = $meta_element->parentNode->removeChild( $meta_element ); } elseif ( Attribute::VIEWPORT === $meta_element->getAttribute( Attribute::NAME ) ) { $this->meta_tags[ self::TAG_VIEWPORT ][] = $meta_element->parentNode->removeChild( $meta_element ); } elseif ( Attribute::AMP_SCRIPT_SRC === $meta_element->getAttribute( Attribute::NAME ) ) { $this->meta_tags[ self::TAG_AMP_SCRIPT_SRC ][] = $meta_element->parentNode->removeChild( $meta_element ); } elseif ( $meta_element->hasAttribute( 'name' ) && preg_match( $this->get_body_meta_tag_name_attribute_deny_pattern(), $meta_element->getAttribute( 'name' ) ) ) { $this->meta_tags[ self::TAG_OTHER ][] = $meta_element->parentNode->removeChild( $meta_element ); } } $this->ensure_charset_is_present(); $this->ensure_viewport_is_present(); $this->process_amp_script_meta_tags(); $this->re_add_meta_tags_in_optimized_order(); $this->ensure_boilerplate_is_present(); } /** * Always ensure that we have an HTML 5 charset meta tag. * * The charset is set to utf-8, which is what AMP requires. */ protected function ensure_charset_is_present() { if ( ! empty( $this->meta_tags[ self::TAG_CHARSET ] ) ) { return; } $this->meta_tags[ self::TAG_CHARSET ][] = $this->create_charset_element(); } /** * Always ensure we have a viewport tag. * * The viewport defaults to 'width=device-width', which is the bare minimum that AMP requires. * If there are `@viewport` style rules, these will have been moved into the content attribute of their own meta[name=viewport] * tags by the style sanitizer. When there are multiple such meta tags, this method extracts the viewport properties of each * and then merges them into a single meta[name=viewport] tag. Any invalid properties will get removed by the * tag-and-attribute sanitizer. */ protected function ensure_viewport_is_present() { if ( empty( $this->meta_tags[ self::TAG_VIEWPORT ] ) ) { $this->meta_tags[ self::TAG_VIEWPORT ][] = $this->create_viewport_element( static::AMP_VIEWPORT ); } else { // Merge one or more meta[name=viewport] tags into one. $parsed_rules = []; /** * Meta viewport element. * * @var DOMElement $meta_viewport */ foreach ( $this->meta_tags[ self::TAG_VIEWPORT ] as $meta_viewport ) { $property_pairs = explode( ',', $meta_viewport->getAttribute( 'content' ) ); foreach ( $property_pairs as $property_pair ) { $exploded_pair = explode( '=', $property_pair, 2 ); if ( isset( $exploded_pair[1] ) ) { $parsed_rules[ trim( $exploded_pair[0] ) ] = trim( $exploded_pair[1] ); } } } // Remove initial-scale=1 to leave just width=device-width in order to avoid a tap delay hurts FID. if ( ! empty( $this->args['remove_initial_scale_viewport_property'] ) && isset( $parsed_rules['initial-scale'] ) && abs( (float) $parsed_rules['initial-scale'] - 1.0 ) < 0.0001 ) { unset( $parsed_rules['initial-scale'] ); } $viewport_value = implode( ',', array_map( static function ( $rule_name ) use ( $parsed_rules ) { return $rule_name . '=' . $parsed_rules[ $rule_name ]; }, array_keys( $parsed_rules ) ) ); $this->meta_tags[ self::TAG_VIEWPORT ] = [ $this->create_viewport_element( $viewport_value ) ]; } } /** * Always ensure we have a style[amp-boilerplate] and a noscript>style[amp-boilerplate]. * * The AMP boilerplate styles should appear at the end of the head: * "Finally, specify the AMP boilerplate code. By putting the boilerplate code last, it prevents custom styles from * accidentally overriding the boilerplate css rules." * * @link https://amp.dev/documentation/guides-and-tutorials/learn/spec/amp-boilerplate/?format=websites * @link https://amp.dev/documentation/guides-and-tutorials/optimize-and-measure/optimize_amp/#optimize-the-amp-runtime-loading */ protected function ensure_boilerplate_is_present() { $style = $this->dom->xpath->query( './style[ @amp-boilerplate ]', $this->dom->head )->item( 0 ); if ( ! $style ) { $style = $this->dom->createElement( Tag::STYLE ); $style->setAttribute( Attribute::AMP_BOILERPLATE, '' ); $style->appendChild( $this->dom->createTextNode( amp_get_boilerplate_stylesheets()[0] ) ); } else { $style->parentNode->removeChild( $style ); // So we can move it. } $this->dom->head->appendChild( $style ); $noscript = $this->dom->xpath->query( './noscript[ style[ @amp-boilerplate ] ]', $this->dom->head )->item( 0 ); if ( ! $noscript ) { $noscript = $this->dom->createElement( Tag::NOSCRIPT ); $style = $this->dom->createElement( Tag::STYLE ); $style->setAttribute( Attribute::AMP_BOILERPLATE, '' ); $style->appendChild( $this->dom->createTextNode( amp_get_boilerplate_stylesheets()[1] ) ); $noscript->appendChild( $style ); } else { $noscript->parentNode->removeChild( $noscript ); // So we can move it. } $this->dom->head->appendChild( $noscript ); } /** * Parse and concatenate source meta tags. */ protected function process_amp_script_meta_tags() { if ( empty( $this->meta_tags[ self::TAG_AMP_SCRIPT_SRC ] ) ) { return; } $first_meta_amp_script_src = array_shift( $this->meta_tags[ self::TAG_AMP_SCRIPT_SRC ] ); $content_values = [ $first_meta_amp_script_src->getAttribute( Attribute::CONTENT ) ]; // Merge (and remove) any subsequent meta amp-script-src elements. while ( ! empty( $this->meta_tags[ self::TAG_AMP_SCRIPT_SRC ] ) ) { $meta_amp_script_src = array_shift( $this->meta_tags[ self::TAG_AMP_SCRIPT_SRC ] ); $content_values[] = $meta_amp_script_src->getAttribute( Attribute::CONTENT ); } $first_meta_amp_script_src->setAttribute( Attribute::CONTENT, implode( ' ', $content_values ) ); $this->meta_tags[ self::TAG_AMP_SCRIPT_SRC ][] = $first_meta_amp_script_src; } /** * Create a new meta tag for the charset value. * * @return DOMElement New meta tag with requested charset. */ protected function create_charset_element() { return AMP_DOM_Utils::create_node( $this->dom, Tag::META, [ Attribute::CHARSET => Encoding::AMP, ] ); } /** * Create a new meta tag for the viewport setting. * * @param string $viewport Viewport setting to use. * @return DOMElement New meta tag with requested viewport setting. */ protected function create_viewport_element( $viewport ) { return AMP_DOM_Utils::create_node( $this->dom, Tag::META, [ Attribute::NAME => Attribute::VIEWPORT, Attribute::CONTENT => $viewport, ] ); } /** * Re-add the meta tags to the node in the optimized order. * * The order is defined by the array entries in $this->meta_tags. * * The optimal loading order for AMP pages is documented at: * https://amp.dev/documentation/guides-and-tutorials/optimize-and-measure/optimize_amp/#optimize-the-amp-runtime-loading * * "1. The first tag should be the meta charset tag, followed by any remaining meta tags." */ protected function re_add_meta_tags_in_optimized_order() { /** * Previous meta tag to append to. * * @var DOMElement $previous_meta_tag */ $previous_meta_tag = null; foreach ( $this->meta_tags as $meta_tag_group ) { foreach ( $meta_tag_group as $meta_tag ) { if ( $previous_meta_tag ) { $previous_meta_tag = $this->dom->head->insertBefore( $meta_tag, $previous_meta_tag->nextSibling ); } else { $previous_meta_tag = $this->dom->head->insertBefore( $meta_tag, $this->dom->head->firstChild ); } } } } }