Flesh out Transformer\ServerSideRendering

composer.json

@@ -53,7 +53,8 @@
   },
   "autoload-dev": {
     "psr-4": {
-      "Amp\\AmpWP\\Tests\\": "tests/php/src/"
+      "Amp\\AmpWP\\Tests\\": "tests/php/src/",
+      "Amp\\Optimizer\\Tests\\": "tests/php/optimizer/src/"
     }
   }
 }

optimizer/Error/CannotRemoveBoilerplate.php

@@ -0,0 +1,92 @@
+<?php
+
+namespace Amp\Optimizer\Error;
+
+use Amp\Optimizer\Error;
+use DOMElement;
+
+final class CannotRemoveBoilerplate implements Error
+{
+
+    use ErrorProperties;
+
+    /**
+     * Code to use for the error.
+     *
+     * @var string
+     */
+    const CODE = 'CANNOT_REMOVE_BOILERPLATE';
+
+    const ATTRIBUTES_STRING             = 'Cannot remove boilerplate as either heights, media or sizes attribute is set: ';
+    const RENDER_DELAYING_SCRIPT_STRING = 'Cannot remove boilerplate because the document contains a render-delaying extension: ';
+    const AMP_AUDIO_STRING              = 'Cannot remove boilerplate because the document contains an extension that needs to know the dimensions of the browser: ';
+    const UNSUPPORTED_LAYOUT_STRING     = 'Cannot remove boilerplate because of an unsupported layout: ';
+
+    /**
+     * Instantiate a CannotRemoveBoilerplate object.
+     *
+     * @param string $message Message for the error.
+     */
+    public function __construct($message)
+    {
+        $this->code    = self::CODE;
+        $this->message = $message;
+    }
+
+    /**
+     * Instantiate a CannotRemoveBoilerplate object for attributes that require the boilerplate to be around.
+     *
+     * @param DOMElement $element Element that contains the attributes that need the boilerplate.
+     * @return self
+     */
+    public static function from_attributes_requiring_boilerplate(DOMElement $element)
+    {
+        return new self(self::ATTRIBUTES_STRING . new ElementDump($element));
+    }
+
+    /**
+     * Instantiate a CannotRemoveBoilerplate object for an amp-experiment element.
+     *
+     * @param DOMElement $element amp-experiment element.
+     * @return self
+     */
+    public static function from_amp_experiment(DOMElement $element)
+    {
+        return new self(self::RENDER_DELAYING_SCRIPT_STRING . $element->tagName);
+    }
+
+    /**
+     * Instantiate a CannotRemoveBoilerplate object for an amp-audio element.
+     *
+     * @param DOMElement $element amp-audio element.
+     * @return self
+     */
+    public static function from_amp_audio(DOMElement $element)
+    {
+        return new self(self::AMP_AUDIO_STRING . new ElementDump($element));
+    }
+
+    /**
+     * Instantiate a CannotRemoveBoilerplate object for an element with an unsupported layout.
+     *
+     * @param DOMElement $element Element with an unsupported layout.
+     * @return self
+     */
+    public static function from_unsupported_layout(DOMElement $element)
+    {
+        return new self(self::UNSUPPORTED_LAYOUT_STRING . new ElementDump($element));
+    }
+
+    /**
+     * Instantiate a CannotRemoveBoilerplate object for an element with an unsupported layout.
+     *
+     * @param DOMElement $element Element with an unsupported layout.
+     * @return self
+     */
+    public static function from_render_delaying_script(DOMElement $element)
+    {
+        $elementName = $element->hasAttribute('custom-element') ? $element->getAttribute('custom-element') : '<unknown>';
+
+        return new self(self::UNSUPPORTED_LAYOUT_STRING . $elementName);
+    }
+}

optimizer/Error/ElementDump.php

@@ -0,0 +1,75 @@
+<?php
+
+namespace Amp\Optimizer\Error;
+
+use DOMAttr;
+use DOMElement;
+
+/**
+ * Dump an element with its attributes.
+ *
+ * This is meant for quick identification of an element and does not dump the child element or other inner content
+ * from that element.
+ */
+final class ElementDump
+{
+
+    /**
+     * Element to dump.
+     *
+     * @var DOMElement
+     */
+    private $element;
+    /**
+     *
+     *
+     * Defaults to 120.
+     *
+     * @var int
+     */
+    private $truncate;
+
+    /**
+     * Instantiate an ElementDump object.
+     *
+     * The object is meant to be cast to a string to do its magic.
+     *
+     * @param DOMElement $element  Element to dump.
+     * @param int        $truncate Optional. Maximum length of the dumped string to truncate to. Defaults to 120.
+     */
+    public function __construct(DOMElement $element, $truncate = 120)
+    {
+        $this->element  = $element;
+        $this->truncate = $truncate;
+    }
+
+    /**
+     * Dump the provided element into a string.
+     *
+     * @return string Dump of the element.
+     */
+    public function __toString()
+    {
+        static $dump = null;
+
+        if ($dump === null) {
+            $dump = sprintf(
+                '%s%s',
+                $this->element->tagName,
+                array_reduce(
+                    iterator_to_array($this->element->attributes, true),
+                    static function ($text, DOMAttr $attribute) {
+                        return $text . " {$attribute->nodeName}=\"{$attribute->value}\"";
+                    },
+                    ''
+                )
+            );
+
+            if (mb_strlen($dump) > $this->truncate) {
+                $dump = mb_substr($dump, 0, $this->truncate - 1) . '…';
+            }
+        }
+
+        return (string)$dump;
+    }
+}

optimizer/TransformationEngine.php

@@ -7,65 +7,68 @@
 final class TransformationEngine
 {
 
-	/**
-	 * Internal storage for the configuration settings.
-	 *
-	 * @var Configuration
-	 */
-	private $configuration;
+    /**
+     * Internal storage for the configuration settings.
+     *
+     * @var Configuration
+     */
+    private $configuration;
 
-	/**
-	 * Instantiate a TransformationEngine object.
-	 *
-	 * @param Configuration $configuration Configuration data to use for setting up the transformers.
-	 */
-	public function __construct(Configuration $configuration)
-	{
-		$this->configuration = $configuration;
-	}
+    /**
+     * Instantiate a TransformationEngine object.
+     *
+     * @param Configuration $configuration Configuration data to use for setting up the transformers.
+     */
+    public function __construct(Configuration $configuration)
+    {
+        $this->configuration = $configuration;
+    }
 
-	/**
-	 * Apply transformations to the provided DOM document.
-	 *
-	 * @param Document $document DOM document to apply the transformations to.
-	 * @return void
-	 */
-	public function optimizeDom(Document $document)
-	{
-		foreach ($this->getTransformers() as $transformer) {
-			$transformer->transform($document);
-		}
-	}
+    /**
+     * 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 optimizeDom(Document $document, ErrorCollection $errors)
+    {
+        foreach ($this->getTransformers() as $transformer) {
+            $transformer->transform($document, $errors);
+        }
+    }
 
-	/**
-	 * Apply transformations to the provided string of HTML markup.
-	 *
-	 * @param string html HTML markup to apply the transformations to.
-	 * @return string Optimized HTML string.
-	 */
-	public function optimizeHtml($html)
-	{
-		$dom = Document::from_html($html);
-		$this->optimizeDom($dom);
-		return $dom->saveHTML();
-	}
+    /**
+     * Apply transformations to the provided string of HTML markup.
+     *
+     * @param string          $html   HTML markup to apply the transformations to.
+     * @param ErrorCollection $errors Collection of errors that are collected during transformation.
+     * @return string Optimized HTML string.
+     */
+    public function optimizeHtml($html, ErrorCollection $errors)
+    {
+        $dom = Document::from_html($html);
+        $this->optimizeDom($dom, $errors);
 
-	/**
-	 * Get the array of transformers to use.
-	 *
-	 * @return Transformer[] Array of transformers to use.
-	 */
-	private function getTransformers()
-	{
-		static $transformers = null;
+        return $dom->saveHTML();
+    }
 
-		if (null === $transformers) {
-			$transformers = [];
-			foreach ($this->configuration->get(Configuration::KEY_TRANSFORMERS) as $transformerClass) {
-				$transformers[$transformerClass] = new $transformerClass();
-			}
-		}
+    /**
+     * Get the array of transformers to use.
+     *
+     * @return Transformer[] Array of transformers to use.
+     */
+    private function getTransformers()
+    {
+        static $transformers = null;
 
-		return $transformers;
-	}
+        if (null === $transformers) {
+            $transformers = [];
+            foreach ($this->configuration->get(Configuration::KEY_TRANSFORMERS) as $transformerClass) {
+                $transformers[$transformerClass] = new $transformerClass();
+            }
+        }
+
+        return $transformers;
+    }
 }

optimizer/Transformer.php

@@ -8,11 +8,12 @@
 interface Transformer
 {
 
-	/**
-	 * Apply transformations to the provided DOM document.
-	 *
-	 * @param Document $document DOM document to apply the transformations to.
-	 * @return void
-	 */
-	public function transform(Document $document);
+    /**
+     * 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);
 }