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\InvalidArgumentException;
use Symfony\Component\DependencyInjection\Exception\RuntimeException;
use Symfony\Component\DependencyInjection\Exception\ServiceNotFoundException;
use Symfony\Component\DependencyInjection\Exception\ServiceCircularReferenceException;
use Symfony\Component\DependencyInjection\ParameterBag\ParameterBagInterface;
use Symfony\Component\DependencyInjection\ParameterBag\ParameterBag;
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 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@symfony.com>
 * @author Johannes M. Schmitt <schmittjoh@gmail.com>
 *
 * @api
 */
class Container implements IntrospectableContainerInterface {
  protected $parameterBag;
  protected $services;
  protected $scopes;
  protected $scopeChildren;
  protected $scopedServices;
  protected $scopeStacks;
  protected $loading = array();

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

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

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

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

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

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

  /**
   * Sets a service.
   *
   * @param string $id      The service identifier
   * @param object $service The service instance
   * @param string $scope   The scope of the service
   *
   * @api
   */
  public function set($id, $service, $scope = self::SCOPE_CONTAINER) {
    if (self::SCOPE_PROTOTYPE === $scope) {
      throw new InvalidArgumentException('You cannot set services of scope "prototype".');
    }
    $id = strtolower($id);
    if (self::SCOPE_CONTAINER !== $scope) {
      if (!isset($this->scopedServices[$scope])) {
        throw new RuntimeException('You cannot set services of inactive scopes.');
      }
      $this->scopedServices[$scope][$id] = $service;
    }
    $this->services[$id] = $service;
  }

  /**
   * Returns true if the given service is defined.
   *
   * @param string $id The service identifier
   *
   * @return Boolean true if the service is defined, false otherwise
   *
   * @api
   */
  public function has($id) {
    $id = strtolower($id);
    return isset($this->services[$id]) || method_exists($this, 'get' . strtr($id, array(
      '_' => '',
      '.' => '_',
    )) . 'Service');
  }

  /**
   * Gets a service.
   *
   * If a service is 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 integer $invalidBehavior The behavior when the service does not exist
   *
   * @return object The associated service
   *
   * @throws InvalidArgumentException if the service is not defined
   *
   * @see Reference
   *
   * @api
   */
  public function get($id, $invalidBehavior = self::EXCEPTION_ON_INVALID_REFERENCE) {
    $id = strtolower($id);
    if (isset($this->services[$id])) {
      return $this->services[$id];
    }
    if (isset($this->loading[$id])) {
      throw new ServiceCircularReferenceException($id, array_keys($this->loading));
    }
    if (method_exists($this, $method = 'get' . strtr($id, array(
      '_' => '',
      '.' => '_',
    )) . 'Service')) {
      $this->loading[$id] = true;
      try {
        $service = $this
          ->{$method}();
      } catch (\Exception $e) {
        unset($this->loading[$id]);
        throw $e;
      }
      unset($this->loading[$id]);
      return $service;
    }
    if (self::EXCEPTION_ON_INVALID_REFERENCE === $invalidBehavior) {
      throw new ServiceNotFoundException($id);
    }
  }

  /**
   * Returns true if the given service has actually been initialized
   *
   * @param string $id The service identifier
   *
   * @return Boolean true if service has already been initialized, false otherwise
   */
  public function initialized($id) {
    return isset($this->services[strtolower($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 $method) {
      if (preg_match('/^get(.+)Service$/', $method->name, $match)) {
        $ids[] = self::underscore($match[1]);
      }
    }
    return array_unique(array_merge($ids, array_keys($this->services)));
  }

  /**
   * This is called when you enter a scope
   *
   * @param string $name
   *
   * @api
   */
  public function enterScope($name) {
    if (!isset($this->scopes[$name])) {
      throw new InvalidArgumentException(sprintf('The scope "%s" does not exist.', $name));
    }
    if (self::SCOPE_CONTAINER !== $this->scopes[$name] && !isset($this->scopedServices[$this->scopes[$name]])) {
      throw new RuntimeException(sprintf('The parent scope "%s" must be active when entering this scope.', $this->scopes[$name]));
    }

    // check if a scope of this name is already active, if so we need to
    // remove all services of this scope, and those of any of its child
    // scopes from the global services map
    if (isset($this->scopedServices[$name])) {
      $services = array(
        $this->services,
        $name => $this->scopedServices[$name],
      );
      unset($this->scopedServices[$name]);
      foreach ($this->scopeChildren[$name] as $child) {
        $services[$child] = $this->scopedServices[$child];
        unset($this->scopedServices[$child]);
      }

      // update global map
      $this->services = call_user_func_array('array_diff_key', $services);
      array_shift($services);

      // add stack entry for this scope so we can restore the removed services later
      if (!isset($this->scopeStacks[$name])) {
        $this->scopeStacks[$name] = new \SplStack();
      }
      $this->scopeStacks[$name]
        ->push($services);
    }
    $this->scopedServices[$name] = array();
  }

  /**
   * This is called to leave the current scope, and move back to the parent
   * scope.
   *
   * @param string $name The name of the scope to leave
   *
   * @throws InvalidArgumentException if the scope is not active
   *
   * @api
   */
  public function leaveScope($name) {
    if (!isset($this->scopedServices[$name])) {
      throw new InvalidArgumentException(sprintf('The scope "%s" is not active.', $name));
    }

    // remove all services of this scope, or any of its child scopes from
    // the global service map
    $services = array(
      $this->services,
      $this->scopedServices[$name],
    );
    unset($this->scopedServices[$name]);
    foreach ($this->scopeChildren[$name] as $child) {
      if (!isset($this->scopedServices[$child])) {
        continue;
      }
      $services[] = $this->scopedServices[$child];
      unset($this->scopedServices[$child]);
    }
    $this->services = call_user_func_array('array_diff_key', $services);

    // check if we need to restore services of a previous scope of this type
    if (isset($this->scopeStacks[$name]) && count($this->scopeStacks[$name]) > 0) {
      $services = $this->scopeStacks[$name]
        ->pop();
      $this->scopedServices += $services;
      array_unshift($services, $this->services);
      $this->services = call_user_func_array('array_merge', $services);
    }
  }

  /**
   * Adds a scope to the container.
   *
   * @param ScopeInterface $scope
   *
   * @api
   */
  public function addScope(ScopeInterface $scope) {
    $name = $scope
      ->getName();
    $parentScope = $scope
      ->getParentName();
    if (self::SCOPE_CONTAINER === $name || self::SCOPE_PROTOTYPE === $name) {
      throw new InvalidArgumentException(sprintf('The scope "%s" is reserved.', $name));
    }
    if (isset($this->scopes[$name])) {
      throw new InvalidArgumentException(sprintf('A scope with name "%s" already exists.', $name));
    }
    if (self::SCOPE_CONTAINER !== $parentScope && !isset($this->scopes[$parentScope])) {
      throw new InvalidArgumentException(sprintf('The parent scope "%s" does not exist, or is invalid.', $parentScope));
    }
    $this->scopes[$name] = $parentScope;
    $this->scopeChildren[$name] = array();

    // normalize the child relations
    while ($parentScope !== self::SCOPE_CONTAINER) {
      $this->scopeChildren[$parentScope][] = $name;
      $parentScope = $this->scopes[$parentScope];
    }
  }

  /**
   * Returns whether this container has a certain scope
   *
   * @param string $name The name of the scope
   *
   * @return Boolean
   *
   * @api
   */
  public function hasScope($name) {
    return isset($this->scopes[$name]);
  }

  /**
   * Returns whether this scope is currently active
   *
   * This does not actually check if the passed scope actually exists.
   *
   * @param string $name
   *
   * @return Boolean
   *
   * @api
   */
  public function isScopeActive($name) {
    return isset($this->scopedServices[$name]);
  }

  /**
   * Camelizes a string.
   *
   * @param string $id A string to camelize
   *
   * @return string The camelized string
   */
  public static function camelize($id) {
    return preg_replace_callback('/(^|_|\\.)+(.)/', function ($match) {
      return ('.' === $match[1] ? '_' : '') . strtoupper($match[2]);
    }, $id);
  }

  /**
   * 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',
    ), strtr($id, '_', '.')));
  }

}