Symfony2: Allow nested parameters in configuration YAML

config.yml

// app/config/config.yml
imports:
    - { resource: parameters.yml }
    - { resource: security.yml }
    # various imports
    - { resource: acmehello.yml }

// app/config/acmehello.yml
acme_hello:
    param:
        one: foo
        two: bar
    other:
        three: baz
    soon: "my value"

sf2-nested-parameters-yml.php

<?php

// src/Acme/HelloBundle/DependencyInjection/Configuration.php

class Configuration implements ConfigurationInterface
{
    /**
     * {@inheritDoc}
     */
    public function getConfigTreeBuilder()
    {
        $treeBuilder = new TreeBuilder();
        $rootNode = $treeBuilder->root('acme_hello');

        return $treeBuilder;
    }
}


// src/Acme/HelloBundle/DependencyInjection/AcmeHelloExtension.php

class AcmeHelloExtension extends Extension
{
    /**
     * Default function that loads values from yaml config files
     */
    public function load(array $configs, ContainerBuilder $container)
    {
        foreach ($configs as $subconfig) {
            $config = $this->unNest($subconfig, null, null, 2);
            foreach ($config as $key => $value) {
                $container->setParameter($key, $value);
            }
        }

        // $configuration = new Configuration();
        // $config = $this->processConfiguration($configuration, $configs);

        $loader = new Loader\YamlFileLoader($container, new FileLocator(__DIR__.'/../Resources/config'));
        $loader->load('config.yml');

    }

    /**
     * The function that parses the array to flatten it into a one level depth array
     *
     * @param $elem     The array containing the config values
     * @param $path     Links each array key to make a condensed key. e.g: $subconfig[param][info][test] becomes $subconfig[param.info.test]
     * @param $result   Each array passed recursively to go down and get the final values
     * @param $maxDepth The maxmium depth to go through the conig array. Once reached, all sub values are returned as array instead of scalar. Useful when you want to store arrays as parameters
     */    
    protected function unNest($elem, $path = null, $result = null, $maxDepth = 10)
    {
        if($result === null){
            $result = array();
        }

        if(is_array($elem) AND $maxDepth){
            foreach ($elem as $key => $value) {
                $newPath = $path ? $path . '.' . $key : $key;
                $result = $this->unNest($value, $newPath, $result, $maxDepth - 1);
            }
        } else {
            $result[$path] = $elem;
        }

        return $result;
    }
}