allow delegation of block rendering

ref #12

In a template, you can now allow rendering of a block from other bundle.

The layout template must explicitly call the rendering of other block,
with the twig function

```
chill_delegated_block('block_name', { 'array' : 'with context' } )
```

This will launch an event
`Chill\MainBundle\Templating\Events\DelegatedBlockRenderingEvent` with
the event's name 'chill_block.block_name'.

You may add content to the page using the function
`DelegatedBlockRenderingEvent::addContent`.

Resources/config/services.yml

@@ -51,6 +51,13 @@ services:
         tags:
             - { name: twig.extension }
             
+    chill.main.twig.delegated_block:
+        class: Chill\MainBundle\Templating\DelegatedBlockRenderingTwig
+        arguments:
+            - "@event_dispatcher"
+        tags:
+            - { name: twig.extension }
+            
     chill.main.twig.csv_cell:
         class: Chill\MainBundle\Templating\CSVCellTwig
         tags:

Templating/DelegatedBlockRenderingTwig.php

@@ -0,0 +1,87 @@
+<?php
+
+/*
+ * Copyright (C) 2016 Champs-Libres <info@champs-libres.coop>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace Chill\MainBundle\Templating;
+
+use Symfony\Component\EventDispatcher\EventDispatcherInterface;
+
+/**
+ * Add the function `chill_delegated_block`.
+ * 
+ * In a template, you can now allow rendering of a block from other bundle.
+ *  
+ *  The layout template must explicitly call the rendering of other block,
+ *  with the twig function
+ *  
+ *  ```
+ *  chill_delegated_block('block_name', { 'array' : 'with context' } )
+ *  ```
+ *  
+ *  This will launch an event
+ *  `Chill\MainBundle\Templating\Events\DelegatedBlockRenderingEvent` with
+ *  the event's name 'chill_block.block_name'.
+ *  
+ *  You may add content to the page using the function
+ *  `DelegatedBlockRenderingEvent::addContent`.
+ * 
+ * See also the documentation of 
+ * `Chill\MainBundle\Templating\Events\DelegatedBlockRenderingEvent`
+ * for usage of this event class
+ * 
+ *
+ * @author Julien Fastré <julien.fastre@champs-libres.coop>
+ */
+class DelegatedBlockRenderingTwig extends \Twig_Extension
+{
+    /**
+     *
+     * @var EventDispatcherInterface
+     */
+    protected $eventDispatcher;
+    
+    public function __construct(EventDispatcherInterface $eventDispatcher)
+    {
+        $this->eventDispatcher = $eventDispatcher;
+    }
+    
+    
+    public function getName()
+    {
+        return 'chill_main_delegated_block';
+    }
+    
+    public function getFunctions()
+    {
+        return array(
+            new \Twig_SimpleFunction('chill_delegated_block', 
+                    array($this, 'renderingDelegatedBlock'),
+                    array('is_safe' => array('html')))
+        );
+    }
+    
+    public function renderingDelegatedBlock($block, array $context)
+    {
+        $event = new Events\DelegatedBlockRenderingEvent($context);
+        
+        $this->eventDispatcher->dispatch('chill_block.'.$block, $event);
+        
+        return $event->getContent();
+    }
+
+}

Templating/Events/DelegatedBlockRenderingEvent.php

@@ -0,0 +1,105 @@
+<?php
+
+/*
+ * Copyright (C) 2016 Champs-Libres <info@champs-libres.coop>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace Chill\MainBundle\Templating\Events;
+
+use Symfony\Component\EventDispatcher\Event;
+
+/**
+ * This event is transmitted on event chill_block.*
+ * 
+ * You may access to the context as an array : 
+ * 
+ * ```
+ * $var = $event['context_key']
+ * ```
+ * 
+ * The documentation for the bundle where the event is launched should give 
+ * you the context keys.
+ * 
+ * The keys are read-only: if you try to update the context using array access
+ * (example, using `$event['context_key'] = $bar;`, an error will be thrown.
+ * 
+ *
+ * @author Julien Fastré <julien.fastre@champs-libres.coop>
+ */
+class DelegatedBlockRenderingEvent extends Event implements \ArrayAccess
+{
+    /**
+     *
+     * @var mixed[]
+     */
+    protected $context;
+    
+    /**
+     * The returned content of the event
+     *
+     * @var string
+     */
+    protected $content = '';
+    
+    public function __construct(array $context)
+    {
+        $this->context = $context;
+    }
+    
+    /**
+     * add content to the event. This content will be printed in the
+     * layout which launched the event
+     * 
+     * @param string $text
+     */
+    public function addContent($text)
+    {
+        $this->content .= $text;
+    }
+    
+    /**
+     * the content of the event
+     * 
+     * @return string
+     */
+    public function getContent()
+    {
+        return $this->content;
+    }
+    
+    public function offsetExists($offset)
+    {
+        return isset($this->context[$offset]);
+    }
+
+    public function offsetGet($offset)
+    {
+        return $this->context[$offset];
+    }
+
+    public function offsetSet($offset, $value)
+    {
+        throw new \RuntimeException("The event context is read-only, you are not "
+                . "allowed to update it.");
+    }
+
+    public function offsetUnset($offset)
+    {
+        throw new \RuntimeException("The event context is read-only, you are not "
+                . "allowed to update it.");
+    }
+
+}