A proxy renderer for agavi, which allows fallback to another renderer, if the first one fails.

AgaviProxyRenderer.class.php

<?php

/**
 * The AgaviProxyRenderer will try to load multiple renderers by name and
 * return the first successful attempt to render the given layer.
 * 
 * This allows you to mix e.g. .twig and .php templates in the same directory,
 * but still use the proper renderer for each file. 
 * 
 * @example <pre>
 *  <!-- Add this to the output_types.xml -->
 *  <renderer name="proxy" class="AgaviProxyRenderer">
 *      <ae:parameter name="renderers">
 *          <ae:parameter>twig</ae:parameter>
 *          <ae:parameter>php</ae:parameter>
 *      </ae:parameter>
 *  </renderer>
 * </pre>
 */
class AgaviProxyRenderer extends AgaviRenderer
{
    public function render(AgaviTemplateLayer $layer, array &$attributes = array(), array &$slots = array(), array &$moreAssigns = array())
    {
        /*
         * FIXME: Maybe there is a better way to retrieve the output type for the given layer
         * and the current renderer.
         */
        if (!isset($moreAssigns['container']))
        {
            throw new AgaviException('Cannot find container in moreAssigns.');
        }
        $container = $moreAssigns['container'];
        $output_type = $container->getOutputType();
        
        
        $layer_extension = $layer->getParameter('extension');
        
        $attempts = array();
        
        foreach ($this->getParameter('renderers') as $renderer_name)
        {
            /**
             * @var $renderer AgaviRenderer
             */
            $renderer = $output_type->getRenderer($renderer_name);
            try
            {
                /*
                 * We need to reconnect the layer to the renderer, since it relies on the
                 * renderer-property to get the the default extension.
                 */
                $layer->setRenderer($renderer);
                
                /*
                 * Setting the renderer is not enough, because we may have the extension set in a previous
                 * iteration. So we have to remove the parameter, if we want to rely on agavi's default
                 * behaviour.
                 */
                if ($layer_extension)
                {
                    $attempts[] = '"' . $renderer_name . '" with extension: ' . $layer_extension;
                    $layer->setParameter('extension', $layer_extension);
                }
                else
                {
                    $attempts[] = '"' . $renderer_name . '" with extension: ' . $renderer->getDefaultExtension();
                    $layer->removeParameter('extension');
                }
                
                return $renderer->render($layer, $attributes, $slots, $moreAssigns);
            }
            catch (AgaviException $exception)
            {
                /*
                 * Ooops, it didn't work. Let's try the next one. BUT if we get a real agavi exception,
                 * throw it. See AgaviStreamTemplateLayer.class.php#L104
                 */
                if (strpos($exception->getMessage(), ' could not be found') < 0)
                {
                    throw $exception;
                }
            }
        }
        
        /*
         * no template found, time to throw an exception
         */ 
        throw new AgaviException('Loading the template "' . $layer->getTemplate() . '" with ' . get_class($this) . ' failed. ' . "\n\n" . 'Renderers tried:' . "\n - " . implode("\n - ", $attempts));
    }
}