feature #19480 [Config] Fix (Yaml|Xml)ReferenceDumper for nested prototypes (ogizanagi)

This PR was merged into the 3.2-dev branch.

Discussion
----------

[Config] Fix (Yaml|Xml)ReferenceDumper for nested prototypes

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

This tries to fix the nested prototypes case for the `YamlReferenceDumper` and `XmlReferenceDumper`.

### Before
```yml
cms_pages:

    # Prototype
    page:                 []
```

### After

```yml
cms_pages:

    # Prototype
    page:

        # Prototype
        locale:
            title:                ~ # Required
            path:                 ~ # Required
```

~~However, the `YamlReferenceDumperTest::testDumper` is marked as skipped, due to another unsupported prototype usage, but that's another issue (the `connections` key). Thus, the bug fix must be tested manually :/ (I'd recommend to merge #19570 first)~~

Commits
-------

1e80510 [Config] Fix YamlReferenceDumper for nested prototypes

src/Symfony/Component/Config/Definition/Dumper/XmlReferenceDumper.php

@@ -96,7 +96,10 @@ class XmlReferenceDumper
                     $rootAttributes[$key] = str_replace('-', ' ', $rootName).' '.$key;
                 }
 
-                if ($prototype instanceof ArrayNode) {
+                if ($prototype instanceof PrototypedArrayNode) {
+                    $prototype->setName($key);
+                    $children = array($key => $prototype);
+                } elseif ($prototype instanceof ArrayNode) {
                     $children = $prototype->getChildren();
                 } else {
                     if ($prototype->hasDefaultValue()) {

src/Symfony/Component/Config/Definition/Dumper/YamlReferenceDumper.php

@@ -199,8 +199,14 @@ class YamlReferenceDumper
 
         if ($prototype instanceof ArrayNode) {
             $keyNode = new ArrayNode($key, $node);
+            $children = $prototype->getChildren();
+
+            if ($prototype instanceof PrototypedArrayNode) {
+                $children = $this->getPrototypeChildren($prototype);
+            }
+
             // add children
-            foreach ($prototype->getChildren() as $childNode) {
+            foreach ($children as $childNode) {
                 $keyNode->addChild($childNode);
             }
         } else {

src/Symfony/Component/Config/Tests/Definition/Dumper/XmlReferenceDumperTest.php

@@ -78,6 +78,20 @@ class XmlReferenceDumperTest extends \PHPUnit_Framework_TestCase
         pass=""
     />
 
+    <!-- prototype -->
+    <cms-page page="cms page page">
+
+        <!-- prototype -->
+        <!-- title: Required -->
+        <!-- path: Required -->
+        <page
+            locale="page locale"
+            title=""
+            path=""
+        />
+
+    </cms-page>
+
 </config>
 
 EOL

src/Symfony/Component/Config/Tests/Definition/Dumper/YamlReferenceDumperTest.php

@@ -65,6 +65,15 @@ acme_root:
         -
             user:                 ~
             pass:                 ~
+    cms_pages:
+
+        # Prototype
+        page:
+
+            # Prototype
+            locale:
+                title:                ~ # Required
+                path:                 ~ # Required
 
 EOL;
     }

src/Symfony/Component/Config/Tests/Fixtures/Configuration/ExampleConfiguration.php

@@ -24,6 +24,7 @@ class ExampleConfiguration implements ConfigurationInterface
         $rootNode
             ->fixXmlConfig('parameter')
             ->fixXmlConfig('connection')
+            ->fixXmlConfig('cms_page')
             ->children()
                 ->booleanNode('boolean')->defaultTrue()->end()
                 ->scalarNode('scalar_empty')->end()
@@ -67,6 +68,18 @@ class ExampleConfiguration implements ConfigurationInterface
                         ->end()
                     ->end()
                 ->end()
+                ->arrayNode('cms_pages')
+                    ->useAttributeAsKey('page')
+                    ->prototype('array')
+                        ->useAttributeAsKey('locale')
+                        ->prototype('array')
+                            ->children()
+                                ->scalarNode('title')->isRequired()->end()
+                                ->scalarNode('path')->isRequired()->end()
+                            ->end()
+                        ->end()
+                    ->end()
+                ->end()
             ->end()
         ;