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

<?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\DependencyInjection;

use Symfony\Component\DependencyInjection\Exception\EnvNotFoundException;
use Symfony\Component\DependencyInjection\Exception\InvalidArgumentException;
use Symfony\Component\DependencyInjection\Exception\ServiceNotFoundException;
use Symfony\Component\DependencyInjection\Exception\ServiceCircularReferenceException;
use Symfony\Component\DependencyInjection\ParameterBag\ParameterBagInterface;
use Symfony\Component\DependencyInjection\ParameterBag\EnvPlaceholderParameterBag;
use Symfony\Component\DependencyInjection\ParameterBag\FrozenParameterBag;

/**
 * Container is a dependency injection container.
 *
 * It gives access to object instances (services).
 *
 * Services and parameters are simple key/pair stores.
 *
 * Parameter keys are case insensitive.
 *
 * 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@symfony.com>
 * @author Johannes M. Schmitt <schmittjoh@gmail.com>
 */
class Container implements ResettableContainerInterface
{
    /**
     * @var ParameterBagInterface
     */
    protected $parameterBag;

    protected $services = array();
    protected $methodMap = array();
    protected $aliases = array();
    protected $loading = array();

    private $envCache = array();
    private $compiled = false;

    /**
     * @param ParameterBagInterface $parameterBag A ParameterBagInterface instance
     */
    public function __construct(ParameterBagInterface $parameterBag = null)
    {
        $this->parameterBag = $parameterBag ?: new EnvPlaceholderParameterBag();
    }

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

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

        $this->compiled = true;
    }

    /**
     * Returns true if the container is compiled.
     *
     * @return bool
     */
    public function isCompiled()
    {
        return $this->compiled;
    }

    /**
     * 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 $name The parameter name
     *
     * @return bool The presence of parameter in container
     */
    public function hasParameter($name)
    {
        return $this->parameterBag->has($name);
    }

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

    /**
     * Sets a service.
     *
     * Setting a service to null resets the service: has() returns false and get()
     * behaves in the same way as if the service was never created.
     *
     * @param string $id      The service identifier
     * @param object $service The service instance
     */
    public function set($id, $service)
    {
        if ('service_container' === $id) {
            throw new InvalidArgumentException('You cannot set service "service_container".');
        }

        if (isset($this->methodMap[$id])) {
            throw new InvalidArgumentException(sprintf('You cannot set the pre-defined service "%s".', $id));
        }

        if (isset($this->aliases[$id])) {
            unset($this->aliases[$id]);
        }

        if (null === $service) {
            unset($this->services[$id]);

            return;
        }

        $this->services[$id] = $service;
    }

    /**
     * Returns true if the given service is defined.
     *
     * @param string $id The service identifier
     *
     * @return bool true if the service is defined, false otherwise
     */
    public function has($id)
    {
        if (isset($this->aliases[$id])) {
            $id = $this->aliases[$id];
        }
        if (isset($this->services[$id])) {
            return true;
        }
        if ('service_container' === $id) {
            return true;
        }

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

        return false;
    }

    /**
     * Gets a service.
     *
     * If a service is defined both through a set() method and
     * with a get{$id}Service() method, the former has always precedence.
     *
     * @param string $id              The service identifier
     * @param int    $invalidBehavior The behavior when the service does not exist
     *
     * @return object The associated service
     *
     * @throws ServiceCircularReferenceException When a circular reference is detected
     * @throws ServiceNotFoundException          When the service is not defined
     * @throws \Exception                        if an exception has been thrown when the service has been resolved
     *
     * @see Reference
     */
    public function get($id, $invalidBehavior = self::EXCEPTION_ON_INVALID_REFERENCE)
    {
        if (isset($this->aliases[$id])) {
            $id = $this->aliases[$id];
        }

        // Re-use shared service instance if it exists.
        if (isset($this->services[$id])) {
            return $this->services[$id];
        }
        if ('service_container' === $id) {
            return $this;
        }

        if (isset($this->loading[$id])) {
            throw new ServiceCircularReferenceException($id, array_keys($this->loading));
        }

        if (isset($this->methodMap[$id])) {
            $method = $this->methodMap[$id];
        } else {
            if (self::EXCEPTION_ON_INVALID_REFERENCE === $invalidBehavior) {
                if (!$id) {
                    throw new ServiceNotFoundException($id);
                }

                $alternatives = array();
                foreach ($this->getServiceIds() as $knownId) {
                    $lev = levenshtein($id, $knownId);
                    if ($lev <= strlen($id) / 3 || false !== strpos($knownId, $id)) {
                        $alternatives[] = $knownId;
                    }
                }

                throw new ServiceNotFoundException($id, null, null, $alternatives);
            }

            return;
        }

        $this->loading[$id] = true;

        try {
            $service = $this->$method();
        } catch (\Exception $e) {
            unset($this->services[$id]);

            throw $e;
        } finally {
            unset($this->loading[$id]);
        }

        return $service;
    }

    /**
     * Returns true if the given service has actually been initialized.
     *
     * @param string $id The service identifier
     *
     * @return bool true if service has already been initialized, false otherwise
     */
    public function initialized($id)
    {
        if (isset($this->aliases[$id])) {
            $id = $this->aliases[$id];
        }

        if ('service_container' === $id) {
            return false;
        }

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

    /**
     * {@inheritdoc}
     */
    public function reset()
    {
        $this->services = array();
    }

    /**
     * Gets all service ids.
     *
     * @return array An array of all defined service ids
     */
    public function getServiceIds()
    {
        return array_unique(array_merge(array('service_container'), array_keys($this->methodMap), array_keys($this->services)));
    }

    /**
     * Camelizes a string.
     *
     * @param string $id A string to camelize
     *
     * @return string The camelized string
     */
    public static function camelize($id)
    {
        return strtr(ucwords(strtr($id, array('_' => ' ', '.' => '_ ', '\\' => '_ '))), array(' ' => ''));
    }

    /**
     * A string to underscore.
     *
     * @param string $id The string to underscore
     *
     * @return string The underscored string
     */
    public static function underscore($id)
    {
        return strtolower(preg_replace(array('/([A-Z]+)([A-Z][a-z])/', '/([a-z\d])([A-Z])/'), array('\\1_\\2', '\\1_\\2'), str_replace('_', '.', $id)));
    }

    /**
     * Fetches a variable from the environment.
     *
     * @param string The name of the environment variable
     *
     * @return scalar The value to use for the provided environment variable name
     *
     * @throws EnvNotFoundException When the environment variable is not found and has no default value
     */
    protected function getEnv($name)
    {
        if (isset($this->envCache[$name]) || array_key_exists($name, $this->envCache)) {
            return $this->envCache[$name];
        }
        if (isset($_ENV[$name])) {
            return $this->envCache[$name] = $_ENV[$name];
        }
        if (false !== $env = getenv($name)) {
            return $this->envCache[$name] = $env;
        }
        if (!$this->hasParameter("env($name)")) {
            throw new EnvNotFoundException($name);
        }

        return $this->envCache[$name] = $this->getParameter("env($name)");
    }

    private function __clone()
    {
    }
}