symfony/src/Symfony/Component/DependencyInjection/Container.php

<?php

namespace Symfony\Component\DependencyInjection;

use Symfony\Component\DependencyInjection\ParameterBag\ParameterBagInterface;
use Symfony\Component\DependencyInjection\ParameterBag\ParameterBag;
use Symfony\Component\DependencyInjection\ParameterBag\FrozenParameterBag;

/*
 * This file is part of the Symfony framework.
 *
 * (c) Fabien Potencier <fabien.potencier@symfony-project.com>
 *
 * This source file is subject to the MIT license that is bundled
 * with this source code in the file LICENSE.
 */

/**
 * Container is a dependency injection container.
 *
 * It gives access to object instances (services).
 *
 * Services and parameters are simple key/pair stores.
 *
 * Parameter and service keys are case insensitive.
 *
 * A service id can contain lowercased letters, digits, underscores, and dots.
 * Underscores are used to separate words, and dots to group services
 * under namespaces:
 *
 * <ul>
 *   <li>request</li>
 *   <li>mysql_session_storage</li>
 *   <li>symfony.mysql_session_storage</li>
 * </ul>
 *
 * A service can also be defined by creating a method named
 * getXXXService(), where XXX is the camelized version of the id:
 *
 * <ul>
 *   <li>request -> getRequestService()</li>
 *   <li>mysql_session_storage -> getMysqlSessionStorageService()</li>
 *   <li>symfony.mysql_session_storage -> getSymfony_MysqlSessionStorageService()</li>
 * </ul>
 *
 * The container can have three possible behaviors when a service does not exist:
 *
 *  * EXCEPTION_ON_INVALID_REFERENCE: Throws an exception (the default)
 *  * NULL_ON_INVALID_REFERENCE:      Returns null
 *  * IGNORE_ON_INVALID_REFERENCE:    Ignores the wrapping command asking for the reference
 *                                    (for instance, ignore a setter if the service does not exist)
 *
 * @author Fabien Potencier <fabien.potencier@symfony-project.com>
 */
class Container implements ContainerInterface
{
    protected $parameterBag;
    protected $services;

    /**
     * Constructor.
     *
     * @param ParameterBagInterface $parameterBag A ParameterBagInterface instance
     */
    public function __construct(ParameterBagInterface $parameterBag = null)
    {
        $this->parameterBag = null === $parameterBag ? new ParameterBag() : $parameterBag;
        $this->services = array();
        $this->set('service_container', $this);
    }

    /**
     * Freezes the container.
     *
     * This method does two things:
     *
     *  * Parameter values are resolved;
     *  * The parameter bag is freezed.
     */
    public function freeze()
    {
        $this->parameterBag->resolve();

        $this->parameterBag = new FrozenParameterBag($this->parameterBag->all());
    }

    /**
     * Returns true if the container parameter bag are frozen.
     *
     * @return Boolean true if the container parameter bag are frozen, false otherwise
     */
    public function isFrozen()
    {
        return $this->parameterBag instanceof FrozenParameterBag;
    }

    /**
     * Gets the service container parameter bag.
     *
     * @return ParameterBagInterface A ParameterBagInterface instance
     */
    public function getParameterBag()
    {
        return $this->parameterBag;
    }

    /**
     * Gets a parameter.
     *
     * @param  string $name The parameter name
     *
     * @return mixed  The parameter value
     *
     * @throws  \InvalidArgumentException if the parameter is not defined
     */
    public function getParameter($name)
    {
        return $this->parameterBag->get($name);
    }

    /**
     * Checks if a parameter exists.
     *
     * @param  string $name The parameter name
     *
     * @return boolean The presence of parameter in container
     */
    public function hasParameter($name)
    {
        return $this->parameterBag->has($name);
    }

    /**
     * Sets a parameter.
     *
     * @param string $name       The parameter name
     * @param mixed  $parameters The parameter value
     */
    public function setParameter($name, $value)
    {
        $this->parameterBag->set($name, $value);
    }

    /**
     * Sets a service.
     *
     * @param string $id      The service identifier
     * @param object $service The service instance
     */
    public function set($id, $service)
    {
        $this->services[strtolower($id)] = $service;
    }

    /**
     * Returns true if the given service is defined.
     *
     * @param  string  $id      The service identifier
     *
     * @return Boolean true if the service is defined, false otherwise
     */
    public function has($id)
    {
        $id = strtolower($id);

        return isset($this->services[$id]) || method_exists($this, 'get'.strtr($id, array('_' => '', '.' => '_')).'Service');
    }

    /**
     * Gets a service.
     *
     * If a service is both defined through a set() method and
     * with a set*Service() method, the former has always precedence.
     *
     * @param  string $id              The service identifier
     * @param  int    $invalidBehavior The behavior when the service does not exist
     *
     * @return object The associated service
     *
     * @throws \InvalidArgumentException if the service is not defined
     *
     * @see Reference
     */
    public function get($id, $invalidBehavior = self::EXCEPTION_ON_INVALID_REFERENCE)
    {
        static $loading = array();

        $id = strtolower($id);

        if (isset($this->services[$id])) {
            return $this->services[$id];
        }

        if (isset($loading[$id])) {
            throw new \LogicException(sprintf('Circular reference detected for service "%s" (services currently loading: %s).', $id, implode(', ', array_keys($loading))));
        }

        if (method_exists($this, $method = 'get'.strtr($id, array('_' => '', '.' => '_')).'Service')) {
            $loading[$id] = true;

            $service = $this->$method();

            unset($loading[$id]);

            return $service;
        }

        if (self::EXCEPTION_ON_INVALID_REFERENCE === $invalidBehavior) {
            throw new \InvalidArgumentException(sprintf('The service "%s" does not exist.', $id));
        }
    }

    /**
     * Gets all service ids.
     *
     * @return array An array of all defined service ids
     */
    public function getServiceIds()
    {
        $ids = array();
        $r = new \ReflectionClass($this);
        foreach ($r->getMethods() as $method) {
            if (preg_match('/^get(.+)Service$/', $name = $method->getName(), $match)) {
                $ids[] = self::underscore($match[1]);
            }
        }

        return array_merge($ids, array_keys($this->services));
    }

    static public function camelize($id)
    {
        return preg_replace(array('/(?:^|_)+(.)/e', '/\.(.)/e'), array("strtoupper('\\1')", "'_'.strtoupper('\\1')"), $id);
    }

    static public function underscore($id)
    {
        return strtolower(preg_replace(array('/([A-Z]+)([A-Z][a-z])/', '/([a-z\d])([A-Z])/'), array('\\1_\\2', '\\1_\\2'), strtr($id, '_', '.')));
    }
}