MDL-49152 output: Templates for renderers (JS and PHP)

Mustache support for rendering templates from either php or js.

lib/outputrenderers.php

@@ -66,6 +66,129 @@ class renderer_base {
      */
     protected $target;
 
+    /**
+     * @var Mustache_Engine $mustache The mustache template compiler
+     */
+    private $mustache;
+
+    /**
+     * @var string $component The component used when requesting this renderer.
+     */
+    private $component;
+
+    /**
+     * @var string $subtype The subtype used when requesting this renderer.
+     */
+    private $subtype;
+
+    /**
+     * This is not done in the constructor because that would be a
+     * compatibility breaking change, and we can just pass this always in the
+     * renderer factory, immediately after creating the renderer.
+     * @since 2.9
+     * @param string $subtype
+     */
+    public function set_subtype($subtype) {
+        $this->subtype = $subtype;
+    }
+
+    /**
+     * This is not done in the constructor because that would be a
+     * compatibility breaking change, and we can just pass this always in the
+     * renderer factory, immediately after creating the renderer.
+     * @since 2.9
+     * @param string $component
+     */
+    public function set_component($component) {
+        $this->component = $component;
+    }
+
+    /**
+     * Return an instance of the mustache class.
+     *
+     * @since 2.9
+     * @return Mustache_Engine
+     */
+    protected function get_mustache() {
+        global $CFG;
+
+        if ($this->mustache === null) {
+            require_once($CFG->dirroot . '/lib/mustache/src/Mustache/Autoloader.php');
+            Mustache_Autoloader::register();
+
+            $themename = $this->page->theme->name;
+            $themerev = theme_get_revision();
+            $target = $this->target;
+
+            $cachedir = make_localcache_directory("mustache/$themerev/$themename/$target");
+            $loaderoptions = array();
+
+            // Where are all the places we should look for templates?
+
+            $suffix = $this->component;
+            if ($this->subtype !== null) {
+                $suffix .= '_' . $this->subtype;
+            }
+
+            // Start with an empty list.
+            $loader = new Mustache_Loader_CascadingLoader(array());
+            $loaderdir = $CFG->dirroot . '/theme/' . $themename . '/templates/' . $suffix;
+            if (is_dir($loaderdir)) {
+                $loader->addLoader(new \core\output\mustache_filesystem_loader($loaderdir, $loaderoptions));
+            }
+
+            // Search each of the parent themes second.
+            foreach ($this->page->theme->parents as $parent) {
+                $loaderdir = $CFG->dirroot . '/theme/' . $parent . '/templates/' . $suffix;
+                if (is_dir($loaderdir)) {
+                    $loader->addLoader(new \core\output\mustache_filesystem_loader($loaderdir, $loaderoptions));
+                }
+            }
+
+            // Look in a components templates dir for a base implementation.
+
+            $compdirectory = core_component::get_component_directory($suffix);
+            if ($compdirectory) {
+                $loaderdir = $compdirectory . '/templates';
+                if (is_dir($loaderdir)) {
+                    $loader->addLoader(new \core\output\mustache_filesystem_loader($loaderdir, $loaderoptions));
+                }
+            }
+
+            // Look in the core templates dir as a final fallback.
+
+            $compdirectory = $CFG->libdir;
+            if ($compdirectory) {
+                $loaderdir = $compdirectory . '/templates';
+                if (is_dir($loaderdir)) {
+                    $loader->addLoader(new \core\output\mustache_filesystem_loader($loaderdir, $loaderoptions));
+                }
+            }
+
+            $stringhelper = new \core\output\mustache_string_helper();
+            $jshelper = new \core\output\mustache_javascript_helper($this->page->requires);
+            $pixhelper = new \core\output\mustache_pix_helper($this);
+
+            // We only expose the variables that are exposed to JS templates.
+            $safeconfig = $this->page->requires->get_config_for_javascript($this->page, $this);
+
+            $helpers = array('config' => $safeconfig,
+                             'str' => array($stringhelper, 'str'),
+                             'js' => array($jshelper, 'help'),
+                             'pix' => array($pixhelper, 'pix'));
+
+            $this->mustache = new Mustache_Engine(array(
+                'cache' => $cachedir,
+                'escape' => 's',
+                'loader' => $loader,
+                'helpers' => $helpers));
+
+        }
+
+        return $this->mustache;
+    }
+
+
     /**
      * Constructor
      *
@@ -83,6 +206,39 @@ class renderer_base {
         $this->target = $target;
     }
 
+    /**
+     * Renders a template by name with the given context.
+     *
+     * The provided data needs to be array/stdClass made up of only simple types.
+     * Simple types are array,stdClass,bool,int,float,string
+     *
+     * @since 2.9
+     * @param array|stdClass $context Context containing data for the template.
+     * @return string|boolean
+     */
+    public function render_from_template($templatename, $context) {
+        static $templatecache = array();
+        $mustache = $this->get_mustache();
+
+        // Provide 1 random value that will not change within a template
+        // but will be different from template to template. This is useful for
+        // e.g. aria attributes that only work with id attributes and must be
+        // unique in a page.
+        $mustache->addHelper('uniqid', new \core\output\mustache_uniqid_helper());
+        if (isset($templatecache[$templatename])) {
+            $template = $templatecache[$templatename];
+        } else {
+            try {
+                $template = $mustache->loadTemplate($templatename);
+                $templatecache[$templatename] = $template;
+            } catch (Mustache_Exception_UnknownTemplateException $e) {
+                throw new moodle_exception('Unknown template: ' . $templatename);
+            }
+        }
+        return trim($template->render($context));
+    }
+
+
     /**
      * Returns rendered widget.
      *
@@ -2016,7 +2172,11 @@ class core_renderer extends renderer_base {
     protected function render_pix_icon(pix_icon $icon) {
         $attributes = $icon->attributes;
         $attributes['src'] = $this->pix_url($icon->pix, $icon->component);
-        return html_writer::empty_tag('img', $attributes);
+        $templatecontext = array();
+        foreach ($attributes as $name => $value) {
+            $templatecontext[] = array('name' => $name, 'value' => $value);
+        }
+        return $this->render_from_template('core/pix_icon', array('attributes' => $templatecontext));
     }
 
     /**