[feature/twig] Able to set chain of namespaces to search for loadTemplate()

This is done so that when event template files are included, if they
include files themselves, that namespace is checked first, then __main__
is checked to include the correct template file.

Also, when template files are included from a particular namespace, this is
done so that the files from that namespace are included first, then the
main namespace is checked.

We may want to change this behavior in the future to allow choosing which
locations have priority, but for now, this is what I am doing to make sure
the behavior is simple and always the same.

PHPBB3-11598

phpBB/includes/template/twig/environment.php

@@ -20,6 +20,9 @@ class phpbb_template_twig_environment extends Twig_Environment
 	/** @var array */
 	protected $phpbbExtensions;
 
+	/** @var array **/
+	protected $namespaceLookUpOrder = array('__main__');
+
     /**
      * Gets the cache filename for a given template.
      *
@@ -36,16 +39,89 @@ class phpbb_template_twig_environment extends Twig_Environment
     	return $this->getCache() . '/' . preg_replace('#[^a-zA-Z0-9_/]#', '_', $name) . '.php';
     }
 
-    public function set_phpbb_extensions($extensions)
-    {
-    	$this->phpbbExtensions = $extensions;
-	}
-
+	/**
+	* Get the list of enabled phpBB extensions
+	*
+	* @return array
+	*/
 	public function get_phpbb_extensions()
 	{
 		return $this->phpbbExtensions;
 	}
 
+    /**
+    * Store the list of enabled phpBB extensions
+    *
+    * @param array $extensions
+    * @return Twig_Environment
+    */
+    public function set_phpbb_extensions($extensions)
+    {
+    	$this->phpbbExtensions = $extensions;
+
+		return $this;
+	}
+
+	/**
+	* Get the namespace look up order
+	*
+	* @return array
+	*/
+	public function getNamespaceLookUpOrder()
+	{
+		return $this->namespaceLookUpOrder;
+	}
+
+	/**
+	* Set the namespace look up order to load templates from
+	*
+	* @param array $namespace
+    * @return Twig_Environment
+	*/
+	public function setNamespaceLookUpOrder($namespace)
+	{
+		$this->namespaceLookUpOrder = $namespace;
+
+		return $this;
+	}
+
+    /**
+     * Loads a template by name.
+     *
+     * @param string  $name  The template name
+     * @param integer $index The index if it is an embedded template
+     *
+     * @return Twig_TemplateInterface A template instance representing the given template name
+     */
+    public function loadTemplate($name, $index = null)
+    {
+    	if (strpos($name, '@') === false)
+    	{
+    		foreach ($this->namespaceLookUpOrder as $namespace)
+    		{
+        		try
+    			{
+    				if ($namespace === '__main__')
+    				{
+    					return parent::loadTemplate($name, $index);
+					}
+
+    				return parent::loadTemplate('@' . $namespace . '/' . $name, $index);
+				}
+				catch (Twig_Error_Loader $e)
+				{
+				}
+			}
+
+			// We were unable to load any templates
+			throw $e;
+		}
+		else
+		{
+    		return parent::loadTemplate($name, $index);
+		}
+    }
+
 	/**
 	* recursive helper to set variables into $context so that Twig can properly fetch them for display
 	*

phpBB/includes/template/twig/node/event.php

@@ -37,7 +37,14 @@ class phpbb_template_twig_node_event extends Twig_Node
 
     		if ($this->environment->getLoader()->exists('@' . $ext_namespace . '/' . $location . '.html'))
     		{
-    			$compiler->write("\$this->env->loadTemplate('@" . $ext_namespace . "/" . $location . ".html')->display(\$context);\n");
+    			$compiler
+    				->write("\$previous_look_up_order = \$this->env->getNamespaceLookUpOrder();\n")
+
+    				// We set the namespace lookup order to be this extension first, then the main path
+    				->write("\$this->env->setNamespaceLookUpOrder(array('" . $ext_namespace . "', '__main__'));\n")
+    				->write("\$this->env->loadTemplate('@" . $ext_namespace . "/" . $location . ".html')->display(\$context);\n")
+    				->write("\$this->env->setNamespaceLookUpOrder(\$previous_look_up_order);\n")
+    			;
 			}
 		}
     }

phpBB/includes/template/twig/node/include.php

@@ -0,0 +1,45 @@
+<?php
+/**
+*
+* @package phpBB3
+* @copyright (c) 2013 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+class phpbb_template_twig_node_include extends Twig_Node_Include
+{
+    /**
+     * Compiles the node to PHP.
+     *
+     * @param Twig_Compiler A Twig_Compiler instance
+     */
+    public function compile(Twig_Compiler $compiler)
+    {
+        $compiler->addDebugInfo($this);
+
+    	$location = $this->getNode('expr')->getAttribute('value');
+    	$namespace = false;
+
+    	if (strpos($location, '@') === 0)
+    	{
+    		$namespace = substr($location, 1, strpos($location, '/') - 1);
+
+    		$compiler
+    			->write("\$previous_look_up_order = \$this->env->getNamespaceLookUpOrder();\n")
+
+    			// We set the namespace lookup order to be this namespace first, then the main path
+    			->write("\$this->env->setNamespaceLookUpOrder(array('" . $namespace . "', '__main__'));\n")
+    		;
+		}
+
+        parent::compile($compiler);
+
+    	if ($namespace)
+    	{
+    		$compiler
+    			->write("\$this->env->setNamespaceLookUpOrder(\$previous_look_up_order);\n")
+    		;
+		}
+    }
+}

phpBB/includes/template/twig/tokenparser/include.php

@@ -21,6 +21,22 @@
  */
 class phpbb_template_twig_tokenparser_include extends Twig_TokenParser_Include
 {
+    /**
+     * Parses a token and returns a node.
+     *
+     * @param Twig_Token $token A Twig_Token instance
+     *
+     * @return Twig_NodeInterface A Twig_NodeInterface instance
+     */
+    public function parse(Twig_Token $token)
+    {
+        $expr = $this->parser->getExpressionParser()->parseExpression();
+
+        list($variables, $only, $ignoreMissing) = $this->parseArguments();
+
+        return new phpbb_template_twig_node_include($expr, $variables, $only, $ignoreMissing, $token->getLine(), $this->getTag());
+    }
+
     /**
      * Gets the tag name associated with this token parser.
      *