and

* tag. It then (re-)inserts the amp-boilerplate unless the document is marked with the i-amphtml-no-boilerplate * attribute. * * This is ported from the Go optimizer. * * Go: * @version c9993b8ac4d17d1f05d3a1289956dadf3f9c370a * @link https://github.com/ampproject/amppackager/blob/c9993b8ac4d17d1f05d3a1289956dadf3f9c370a/transformer/transformers/ampboilerplate.go * * @package ampproject/amp-toolbox */ final class AmpBoilerplate implements Transformer { /** * Apply transformations to the provided DOM document. * * @param Document $document DOM document to apply the transformations to. * @param ErrorCollection $errors Collection of errors that are collected during transformation. * @return void */ public function transform(Document $document, ErrorCollection $errors) { $this->removeStyleAndNoscriptTags($document); if ($this->hasNoBoilerplateAttribute($document)) { return; } list($boilerplate, $css) = $this->determineBoilerplateAndCss($document->html); $styleNode = $document->createElement(Tag::STYLE); $styleNode->setAttribute($boilerplate, ''); $document->head->appendChild($styleNode); $cssNode = $document->createTextNode($css); $styleNode->appendChild($cssNode); if ($boilerplate !== Attribute::AMP_BOILERPLATE) { return; } // Regular AMP boilerplate also includes a <noscript> element. $noscriptNode = $document->createElement(Tag::NOSCRIPT); $document->head->appendChild($noscriptNode); $noscriptStyleNode = $document->createElement(Tag::STYLE); $noscriptStyleNode->setAttribute($boilerplate, ''); $noscriptNode->appendChild($noscriptStyleNode); $noscriptCssNode = $document->createTextNode(Amp::BOILERPLATE_NOSCRIPT_CSS); $noscriptStyleNode->appendChild($noscriptCssNode); } /** * Remove all <style> and <noscript> tags which are for the boilerplate. * * @param Document $document Document to remove the tags from. */ private function removeStyleAndNoscriptTags(Document $document) { /** * Style element. * * @var Element $style */ foreach (iterator_to_array($document->head->getElementsByTagName(Tag::STYLE)) as $style) { if (! $this->isBoilerplateStyle($style)) { continue; } if (Tag::NOSCRIPT === $style->parentNode->nodeName) { $style->parentNode->parentNode->removeChild($style->parentNode); } else { $style->parentNode->removeChild($style); } } } /** * Check whether an element is a boilerplate style. * * @param Element $element Element to check. * @return bool Whether the element is a boilerplate style. */ private function isBoilerplateStyle(Element $element) { foreach (Attribute::ALL_BOILERPLATES as $boilerplate) { if ($element->hasAttribute($boilerplate)) { return true; } } return false; } /** * Check whether it was already determined the boilerplate should be removed. * * We want to ensure we don't apply re-add the boilerplate again if it was already removed via SSR. * * @param Document $document DOM document to check for the attribute. * @return bool Whether it was determined that the boilerplate should be removed. */ private function hasNoBoilerplateAttribute(Document $document) { if ($document->html->hasAttribute(Amp::NO_BOILERPLATE_ATTRIBUTE)) { return true; } return false; } /** * Determine and return the boilerplate attribute and inline CSS to use. * * @param Element $htmlElement HTML DOM element to check against. * @return array Tuple containing the $boilerplate and $css to use. */ private function determineBoilerplateAndCss(Element $htmlElement) { $boilerplate = Attribute::AMP_BOILERPLATE; $css = Amp::BOILERPLATE_CSS; foreach (Attribute::ALL_AMP4ADS as $attribute) { if ( $htmlElement->hasAttribute($attribute) || ( $htmlElement->getAttribute(Document::EMOJI_AMP_ATTRIBUTE_PLACEHOLDER) === str_replace( Attribute::AMP_EMOJI, '', $attribute ) ) ) { $boilerplate = Attribute::AMP4ADS_BOILERPLATE; $css = Amp::AMP4ADS_AND_AMP4EMAIL_BOILERPLATE_CSS; } } foreach (Attribute::ALL_AMP4EMAIL as $attribute) { if ( $htmlElement->hasAttribute($attribute) || ( $htmlElement->getAttribute(Document::EMOJI_AMP_ATTRIBUTE_PLACEHOLDER) === str_replace( Attribute::AMP_EMOJI, '', $attribute ) ) ) { $boilerplate = Attribute::AMP4EMAIL_BOILERPLATE; $css = Amp::AMP4ADS_AND_AMP4EMAIL_BOILERPLATE_CSS; } } return [$boilerplate, $css]; } }