<?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\Compiler\Compiler;
use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
use Symfony\Component\DependencyInjection\Compiler\PassConfig;
use Symfony\Component\DependencyInjection\Exception\BadMethodCallException;
use Symfony\Component\DependencyInjection\Exception\InvalidArgumentException;
use Symfony\Component\DependencyInjection\Exception\LogicException;
use Symfony\Component\DependencyInjection\Exception\RuntimeException;
use Symfony\Component\DependencyInjection\Exception\ServiceCircularReferenceException;
use Symfony\Component\DependencyInjection\Exception\ServiceNotFoundException;
use Symfony\Component\DependencyInjection\Extension\ExtensionInterface;
use Symfony\Component\Config\Resource\FileResource;
use Symfony\Component\Config\Resource\ResourceInterface;
use Symfony\Component\DependencyInjection\LazyProxy\Instantiator\InstantiatorInterface;
use Symfony\Component\DependencyInjection\LazyProxy\Instantiator\RealServiceInstantiator;
use Symfony\Component\ExpressionLanguage\Expression;
use Symfony\Component\ExpressionLanguage\ExpressionFunctionProviderInterface;

/**
 * ContainerBuilder is a DI container that provides an API to easily describe services.
 *
 * @author Fabien Potencier <fabien@symfony.com>
 */
class ContainerBuilder extends Container implements TaggedContainerInterface
{
    /**
     * @var ExtensionInterface[]
     */
    private $extensions = array();

    /**
     * @var ExtensionInterface[]
     */
    private $extensionsByNs = array();

    /**
     * @var Definition[]
     */
    private $definitions = array();

    /**
     * @var Alias[]
     */
    private $aliasDefinitions = array();

    /**
     * @var ResourceInterface[]
     */
    private $resources = array();

    private $extensionConfigs = array();

    /**
     * @var Compiler
     */
    private $compiler;

    private $trackResources = true;

    /**
     * @var InstantiatorInterface|null
     */
    private $proxyInstantiator;

    /**
     * @var ExpressionLanguage|null
     */
    private $expressionLanguage;

    /**
     * @var ExpressionFunctionProviderInterface[]
     */
    private $expressionLanguageProviders = array();

    /**
     * @var string[] with tag names used by findTaggedServiceIds
     */
    private $usedTags = array();

    /**
     * Sets the track resources flag.
     *
     * If you are not using the loaders and therefore don't want
     * to depend on the Config component, set this flag to false.
     *
     * @param bool $track true if you want to track resources, false otherwise
     */
    public function setResourceTracking($track)
    {
        $this->trackResources = (bool) $track;
    }

    /**
     * Checks if resources are tracked.
     *
     * @return bool true if resources are tracked, false otherwise
     */
    public function isTrackingResources()
    {
        return $this->trackResources;
    }

    /**
     * Sets the instantiator to be used when fetching proxies.
     *
     * @param InstantiatorInterface $proxyInstantiator
     */
    public function setProxyInstantiator(InstantiatorInterface $proxyInstantiator)
    {
        $this->proxyInstantiator = $proxyInstantiator;
    }

    /**
     * Registers an extension.
     *
     * @param ExtensionInterface $extension An extension instance
     */
    public function registerExtension(ExtensionInterface $extension)
    {
        $this->extensions[$extension->getAlias()] = $extension;

        if (false !== $extension->getNamespace()) {
            $this->extensionsByNs[$extension->getNamespace()] = $extension;
        }
    }

    /**
     * Returns an extension by alias or namespace.
     *
     * @param string $name An alias or a namespace
     *
     * @return ExtensionInterface An extension instance
     *
     * @throws LogicException if the extension is not registered
     */
    public function getExtension($name)
    {
        if (isset($this->extensions[$name])) {
            return $this->extensions[$name];
        }

        if (isset($this->extensionsByNs[$name])) {
            return $this->extensionsByNs[$name];
        }

        throw new LogicException(sprintf('Container extension "%s" is not registered', $name));
    }

    /**
     * Returns all registered extensions.
     *
     * @return ExtensionInterface[] An array of ExtensionInterface
     */
    public function getExtensions()
    {
        return $this->extensions;
    }

    /**
     * Checks if we have an extension.
     *
     * @param string $name The name of the extension
     *
     * @return bool If the extension exists
     */
    public function hasExtension($name)
    {
        return isset($this->extensions[$name]) || isset($this->extensionsByNs[$name]);
    }

    /**
     * Returns an array of resources loaded to build this configuration.
     *
     * @return ResourceInterface[] An array of resources
     */
    public function getResources()
    {
        return array_unique($this->resources);
    }

    /**
     * Adds a resource for this configuration.
     *
     * @param ResourceInterface $resource A resource instance
     *
     * @return $this
     */
    public function addResource(ResourceInterface $resource)
    {
        if (!$this->trackResources) {
            return $this;
        }

        $this->resources[] = $resource;

        return $this;
    }

    /**
     * Sets the resources for this configuration.
     *
     * @param ResourceInterface[] $resources An array of resources
     *
     * @return $this
     */
    public function setResources(array $resources)
    {
        if (!$this->trackResources) {
            return $this;
        }

        $this->resources = $resources;

        return $this;
    }

    /**
     * Adds the object class hierarchy as resources.
     *
     * @param object $object An object instance
     *
     * @return $this
     */
    public function addObjectResource($object)
    {
        if ($this->trackResources) {
            $this->addClassResource(new \ReflectionClass($object));
        }

        return $this;
    }

    /**
     * Adds the given class hierarchy as resources.
     *
     * @param \ReflectionClass $class
     *
     * @return $this
     */
    public function addClassResource(\ReflectionClass $class)
    {
        if (!$this->trackResources) {
            return $this;
        }

        do {
            if (is_file($class->getFileName())) {
                $this->addResource(new FileResource($class->getFileName()));
            }
        } while ($class = $class->getParentClass());

        return $this;
    }

    /**
     * Loads the configuration for an extension.
     *
     * @param string $extension The extension alias or namespace
     * @param array  $values    An array of values that customizes the extension
     *
     * @return $this
     *
     * @throws BadMethodCallException When this ContainerBuilder is frozen
     * @throws \LogicException        if the container is frozen
     */
    public function loadFromExtension($extension, array $values = array())
    {
        if ($this->isFrozen()) {
            throw new BadMethodCallException('Cannot load from an extension on a frozen container.');
        }

        $namespace = $this->getExtension($extension)->getAlias();

        $this->extensionConfigs[$namespace][] = $values;

        return $this;
    }

    /**
     * Adds a compiler pass.
     *
     * @param CompilerPassInterface $pass A compiler pass
     * @param string                $type The type of compiler pass
     *
     * @return $this
     */
    public function addCompilerPass(CompilerPassInterface $pass, $type = PassConfig::TYPE_BEFORE_OPTIMIZATION)
    {
        $this->getCompiler()->addPass($pass, $type);

        $this->addObjectResource($pass);

        return $this;
    }

    /**
     * Returns the compiler pass config which can then be modified.
     *
     * @return PassConfig The compiler pass config
     */
    public function getCompilerPassConfig()
    {
        return $this->getCompiler()->getPassConfig();
    }

    /**
     * Returns the compiler.
     *
     * @return Compiler The compiler
     */
    public function getCompiler()
    {
        if (null === $this->compiler) {
            $this->compiler = new Compiler();
        }

        return $this->compiler;
    }

    /**
     * Sets a service.
     *
     * @param string $id      The service identifier
     * @param object $service The service instance
     *
     * @throws BadMethodCallException When this ContainerBuilder is frozen
     */
    public function set($id, $service)
    {
        $id = strtolower($id);

        if ($this->isFrozen() && (isset($this->definitions[$id]) && !$this->definitions[$id]->isSynthetic())) {
            // setting a synthetic service on a frozen container is alright
            throw new BadMethodCallException(sprintf('Setting service "%s" for an unknown or non-synthetic service definition on a frozen container is not allowed.', $id));
        }

        unset($this->definitions[$id], $this->aliasDefinitions[$id]);

        parent::set($id, $service);
    }

    /**
     * Removes a service definition.
     *
     * @param string $id The service identifier
     */
    public function removeDefinition($id)
    {
        unset($this->definitions[strtolower($id)]);
    }

    /**
     * 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)
    {
        $id = strtolower($id);

        return isset($this->definitions[$id]) || isset($this->aliasDefinitions[$id]) || parent::has($id);
    }

    /**
     * Gets a service.
     *
     * @param string $id              The service identifier
     * @param int    $invalidBehavior The behavior when the service does not exist
     *
     * @return object The associated service
     *
     * @throws InvalidArgumentException          when no definitions are available
     * @throws ServiceCircularReferenceException When a circular reference is detected
     * @throws ServiceNotFoundException          When the service is not defined
     * @throws \Exception
     *
     * @see Reference
     */
    public function get($id, $invalidBehavior = ContainerInterface::EXCEPTION_ON_INVALID_REFERENCE)
    {
        $id = strtolower($id);

        if ($service = parent::get($id, ContainerInterface::NULL_ON_INVALID_REFERENCE)) {
            return $service;
        }

        if (!isset($this->definitions[$id]) && isset($this->aliasDefinitions[$id])) {
            return $this->get((string) $this->aliasDefinitions[$id], $invalidBehavior);
        }

        try {
            $definition = $this->getDefinition($id);
        } catch (ServiceNotFoundException $e) {
            if (ContainerInterface::EXCEPTION_ON_INVALID_REFERENCE !== $invalidBehavior) {
                return;
            }

            throw $e;
        }

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

        try {
            $service = $this->createService($definition, $id);
        } finally {
            unset($this->loading[$id]);
        }

        return $service;
    }

    /**
     * Merges a ContainerBuilder with the current ContainerBuilder configuration.
     *
     * Service definitions overrides the current defined ones.
     *
     * But for parameters, they are overridden by the current ones. It allows
     * the parameters passed to the container constructor to have precedence
     * over the loaded ones.
     *
     * $container = new ContainerBuilder(array('foo' => 'bar'));
     * $loader = new LoaderXXX($container);
     * $loader->load('resource_name');
     * $container->register('foo', new stdClass());
     *
     * In the above example, even if the loaded resource defines a foo
     * parameter, the value will still be 'bar' as defined in the ContainerBuilder
     * constructor.
     *
     * @param ContainerBuilder $container The ContainerBuilder instance to merge
     *
     * @throws BadMethodCallException When this ContainerBuilder is frozen
     */
    public function merge(ContainerBuilder $container)
    {
        if ($this->isFrozen()) {
            throw new BadMethodCallException('Cannot merge on a frozen container.');
        }

        $this->addDefinitions($container->getDefinitions());
        $this->addAliases($container->getAliases());
        $this->getParameterBag()->add($container->getParameterBag()->all());

        if ($this->trackResources) {
            foreach ($container->getResources() as $resource) {
                $this->addResource($resource);
            }
        }

        foreach ($this->extensions as $name => $extension) {
            if (!isset($this->extensionConfigs[$name])) {
                $this->extensionConfigs[$name] = array();
            }

            $this->extensionConfigs[$name] = array_merge($this->extensionConfigs[$name], $container->getExtensionConfig($name));
        }
    }

    /**
     * Returns the configuration array for the given extension.
     *
     * @param string $name The name of the extension
     *
     * @return array An array of configuration
     */
    public function getExtensionConfig($name)
    {
        if (!isset($this->extensionConfigs[$name])) {
            $this->extensionConfigs[$name] = array();
        }

        return $this->extensionConfigs[$name];
    }

    /**
     * Prepends a config array to the configs of the given extension.
     *
     * @param string $name   The name of the extension
     * @param array  $config The config to set
     */
    public function prependExtensionConfig($name, array $config)
    {
        if (!isset($this->extensionConfigs[$name])) {
            $this->extensionConfigs[$name] = array();
        }

        array_unshift($this->extensionConfigs[$name], $config);
    }

    /**
     * Compiles the container.
     *
     * This method passes the container to compiler
     * passes whose job is to manipulate and optimize
     * the container.
     *
     * The main compiler passes roughly do four things:
     *
     *  * The extension configurations are merged;
     *  * Parameter values are resolved;
     *  * The parameter bag is frozen;
     *  * Extension loading is disabled.
     */
    public function compile()
    {
        $compiler = $this->getCompiler();

        if ($this->trackResources) {
            foreach ($compiler->getPassConfig()->getPasses() as $pass) {
                $this->addObjectResource($pass);
            }
        }

        $compiler->compile($this);

        if ($this->trackResources) {
            foreach ($this->definitions as $definition) {
                if ($definition->isLazy() && ($class = $definition->getClass()) && class_exists($class)) {
                    $this->addClassResource(new \ReflectionClass($class));
                }
            }
        }

        $this->extensionConfigs = array();

        parent::compile();
    }

    /**
     * Gets all service ids.
     *
     * @return array An array of all defined service ids
     */
    public function getServiceIds()
    {
        return array_unique(array_merge(array_keys($this->getDefinitions()), array_keys($this->aliasDefinitions), parent::getServiceIds()));
    }

    /**
     * Adds the service aliases.
     *
     * @param array $aliases An array of aliases
     */
    public function addAliases(array $aliases)
    {
        foreach ($aliases as $alias => $id) {
            $this->setAlias($alias, $id);
        }
    }

    /**
     * Sets the service aliases.
     *
     * @param array $aliases An array of aliases
     */
    public function setAliases(array $aliases)
    {
        $this->aliasDefinitions = array();
        $this->addAliases($aliases);
    }

    /**
     * Sets an alias for an existing service.
     *
     * @param string       $alias The alias to create
     * @param string|Alias $id    The service to alias
     *
     * @throws InvalidArgumentException if the id is not a string or an Alias
     * @throws InvalidArgumentException if the alias is for itself
     */
    public function setAlias($alias, $id)
    {
        $alias = strtolower($alias);

        if (is_string($id)) {
            $id = new Alias($id);
        } elseif (!$id instanceof Alias) {
            throw new InvalidArgumentException('$id must be a string, or an Alias object.');
        }

        if ($alias === (string) $id) {
            throw new InvalidArgumentException(sprintf('An alias can not reference itself, got a circular reference on "%s".', $alias));
        }

        unset($this->definitions[$alias]);

        $this->aliasDefinitions[$alias] = $id;
    }

    /**
     * Removes an alias.
     *
     * @param string $alias The alias to remove
     */
    public function removeAlias($alias)
    {
        unset($this->aliasDefinitions[strtolower($alias)]);
    }

    /**
     * Returns true if an alias exists under the given identifier.
     *
     * @param string $id The service identifier
     *
     * @return bool true if the alias exists, false otherwise
     */
    public function hasAlias($id)
    {
        return isset($this->aliasDefinitions[strtolower($id)]);
    }

    /**
     * Gets all defined aliases.
     *
     * @return Alias[] An array of aliases
     */
    public function getAliases()
    {
        return $this->aliasDefinitions;
    }

    /**
     * Gets an alias.
     *
     * @param string $id The service identifier
     *
     * @return Alias An Alias instance
     *
     * @throws InvalidArgumentException if the alias does not exist
     */
    public function getAlias($id)
    {
        $id = strtolower($id);

        if (!isset($this->aliasDefinitions[$id])) {
            throw new InvalidArgumentException(sprintf('The service alias "%s" does not exist.', $id));
        }

        return $this->aliasDefinitions[$id];
    }

    /**
     * Registers a service definition.
     *
     * This methods allows for simple registration of service definition
     * with a fluid interface.
     *
     * @param string $id    The service identifier
     * @param string $class The service class
     *
     * @return Definition A Definition instance
     */
    public function register($id, $class = null)
    {
        return $this->setDefinition($id, new Definition($class));
    }

    /**
     * Adds the service definitions.
     *
     * @param Definition[] $definitions An array of service definitions
     */
    public function addDefinitions(array $definitions)
    {
        foreach ($definitions as $id => $definition) {
            $this->setDefinition($id, $definition);
        }
    }

    /**
     * Sets the service definitions.
     *
     * @param Definition[] $definitions An array of service definitions
     */
    public function setDefinitions(array $definitions)
    {
        $this->definitions = array();
        $this->addDefinitions($definitions);
    }

    /**
     * Gets all service definitions.
     *
     * @return Definition[] An array of Definition instances
     */
    public function getDefinitions()
    {
        return $this->definitions;
    }

    /**
     * Sets a service definition.
     *
     * @param string     $id         The service identifier
     * @param Definition $definition A Definition instance
     *
     * @return Definition the service definition
     *
     * @throws BadMethodCallException When this ContainerBuilder is frozen
     */
    public function setDefinition($id, Definition $definition)
    {
        if ($this->isFrozen()) {
            throw new BadMethodCallException('Adding definition to a frozen container is not allowed');
        }

        $id = strtolower($id);

        unset($this->aliasDefinitions[$id]);

        return $this->definitions[$id] = $definition;
    }

    /**
     * Returns true if a service definition exists under the given identifier.
     *
     * @param string $id The service identifier
     *
     * @return bool true if the service definition exists, false otherwise
     */
    public function hasDefinition($id)
    {
        return isset($this->definitions[strtolower($id)]);
    }

    /**
     * Gets a service definition.
     *
     * @param string $id The service identifier
     *
     * @return Definition A Definition instance
     *
     * @throws ServiceNotFoundException if the service definition does not exist
     */
    public function getDefinition($id)
    {
        $id = strtolower($id);

        if (!isset($this->definitions[$id])) {
            throw new ServiceNotFoundException($id);
        }

        return $this->definitions[$id];
    }

    /**
     * Gets a service definition by id or alias.
     *
     * The method "unaliases" recursively to return a Definition instance.
     *
     * @param string $id The service identifier or alias
     *
     * @return Definition A Definition instance
     *
     * @throws ServiceNotFoundException if the service definition does not exist
     */
    public function findDefinition($id)
    {
        $id = strtolower($id);

        while (isset($this->aliasDefinitions[$id])) {
            $id = (string) $this->aliasDefinitions[$id];
        }

        return $this->getDefinition($id);
    }

    /**
     * Creates a service for a service definition.
     *
     * @param Definition $definition A service definition instance
     * @param string     $id         The service identifier
     * @param bool       $tryProxy   Whether to try proxying the service with a lazy proxy
     *
     * @return object The service described by the service definition
     *
     * @throws RuntimeException         When the factory definition is incomplete
     * @throws RuntimeException         When the service is a synthetic service
     * @throws InvalidArgumentException When configure callable is not callable
     */
    private function createService(Definition $definition, $id, $tryProxy = true)
    {
        if ($definition instanceof DefinitionDecorator) {
            throw new RuntimeException(sprintf('Constructing service "%s" from a parent definition is not supported at build time.', $id));
        }

        if ($definition->isSynthetic()) {
            throw new RuntimeException(sprintf('You have requested a synthetic service ("%s"). The DIC does not know how to construct this service.', $id));
        }

        if ($definition->isDeprecated()) {
            @trigger_error($definition->getDeprecationMessage($id), E_USER_DEPRECATED);
        }

        if ($tryProxy && $definition->isLazy()) {
            $proxy = $this
                ->getProxyInstantiator()
                ->instantiateProxy(
                    $this,
                    $definition,
                    $id, function () use ($definition, $id) {
                        return $this->createService($definition, $id, false);
                    }
                );
            $this->shareService($definition, $proxy, $id);

            return $proxy;
        }

        $parameterBag = $this->getParameterBag();

        if (null !== $definition->getFile()) {
            require_once $parameterBag->resolveValue($definition->getFile());
        }

        $arguments = $this->resolveServices($parameterBag->unescapeValue($parameterBag->resolveValue($definition->getArguments())));

        if (null !== $factory = $definition->getFactory()) {
            if (is_array($factory)) {
                $factory = array($this->resolveServices($parameterBag->resolveValue($factory[0])), $factory[1]);
            } elseif (!is_string($factory)) {
                throw new RuntimeException(sprintf('Cannot create service "%s" because of invalid factory', $id));
            }

            $service = call_user_func_array($factory, $arguments);

            if (!$definition->isDeprecated() && is_array($factory) && is_string($factory[0])) {
                $r = new \ReflectionClass($factory[0]);

                if (0 < strpos($r->getDocComment(), "\n * @deprecated ")) {
                    @trigger_error(sprintf('The "%s" service relies on the deprecated "%s" factory class. It should either be deprecated or its factory upgraded.', $id, $r->name), E_USER_DEPRECATED);
                }
            }
        } else {
            $r = new \ReflectionClass($parameterBag->resolveValue($definition->getClass()));

            $service = null === $r->getConstructor() ? $r->newInstance() : $r->newInstanceArgs($arguments);

            if (!$definition->isDeprecated() && 0 < strpos($r->getDocComment(), "\n * @deprecated ")) {
                @trigger_error(sprintf('The "%s" service relies on the deprecated "%s" class. It should either be deprecated or its implementation upgraded.', $id, $r->name), E_USER_DEPRECATED);
            }
        }

        if ($tryProxy || !$definition->isLazy()) {
            // share only if proxying failed, or if not a proxy
            $this->shareService($definition, $service, $id);
        }

        $properties = $this->resolveServices($parameterBag->unescapeValue($parameterBag->resolveValue($definition->getProperties())));
        foreach ($properties as $name => $value) {
            $service->$name = $value;
        }

        foreach ($definition->getMethodCalls() as $call) {
            $this->callMethod($service, $call);
        }

        if ($callable = $definition->getConfigurator()) {
            if (is_array($callable)) {
                $callable[0] = $parameterBag->resolveValue($callable[0]);

                if ($callable[0] instanceof Reference) {
                    $callable[0] = $this->get((string) $callable[0], $callable[0]->getInvalidBehavior());
                } elseif ($callable[0] instanceof Definition) {
                    $callable[0] = $this->createService($callable[0], null);
                }
            }

            if (!is_callable($callable)) {
                throw new InvalidArgumentException(sprintf('The configure callable for class "%s" is not a callable.', get_class($service)));
            }

            call_user_func($callable, $service);
        }

        return $service;
    }

    /**
     * Replaces service references by the real service instance and evaluates expressions.
     *
     * @param mixed $value A value
     *
     * @return mixed The same value with all service references replaced by
     *               the real service instances and all expressions evaluated
     */
    public function resolveServices($value)
    {
        if (is_array($value)) {
            foreach ($value as $k => $v) {
                $value[$k] = $this->resolveServices($v);
            }
        } elseif ($value instanceof Reference) {
            $value = $this->get((string) $value, $value->getInvalidBehavior());
        } elseif ($value instanceof Definition) {
            $value = $this->createService($value, null);
        } elseif ($value instanceof Expression) {
            $value = $this->getExpressionLanguage()->evaluate($value, array('container' => $this));
        }

        return $value;
    }

    /**
     * Returns service ids for a given tag.
     *
     * Example:
     *
     * $container->register('foo')->addTag('my.tag', array('hello' => 'world'));
     *
     * $serviceIds = $container->findTaggedServiceIds('my.tag');
     * foreach ($serviceIds as $serviceId => $tags) {
     *     foreach ($tags as $tag) {
     *         echo $tag['hello'];
     *     }
     * }
     *
     * @param string $name The tag name
     *
     * @return array An array of tags with the tagged service as key, holding a list of attribute arrays
     */
    public function findTaggedServiceIds($name)
    {
        $this->usedTags[] = $name;
        $tags = array();
        foreach ($this->getDefinitions() as $id => $definition) {
            if ($definition->hasTag($name)) {
                $tags[$id] = $definition->getTag($name);
            }
        }

        return $tags;
    }

    /**
     * Returns all tags the defined services use.
     *
     * @return array An array of tags
     */
    public function findTags()
    {
        $tags = array();
        foreach ($this->getDefinitions() as $id => $definition) {
            $tags = array_merge(array_keys($definition->getTags()), $tags);
        }

        return array_unique($tags);
    }

    /**
     * Returns all tags not queried by findTaggedServiceIds.
     *
     * @return string[] An array of tags
     */
    public function findUnusedTags()
    {
        return array_values(array_diff($this->findTags(), $this->usedTags));
    }

    public function addExpressionLanguageProvider(ExpressionFunctionProviderInterface $provider)
    {
        $this->expressionLanguageProviders[] = $provider;
    }

    /**
     * @return ExpressionFunctionProviderInterface[]
     */
    public function getExpressionLanguageProviders()
    {
        return $this->expressionLanguageProviders;
    }

    /**
     * Returns the Service Conditionals.
     *
     * @param mixed $value An array of conditionals to return
     *
     * @return array An array of Service conditionals
     */
    public static function getServiceConditionals($value)
    {
        $services = array();

        if (is_array($value)) {
            foreach ($value as $v) {
                $services = array_unique(array_merge($services, self::getServiceConditionals($v)));
            }
        } elseif ($value instanceof Reference && $value->getInvalidBehavior() === ContainerInterface::IGNORE_ON_INVALID_REFERENCE) {
            $services[] = (string) $value;
        }

        return $services;
    }

    /**
     * Retrieves the currently set proxy instantiator or instantiates one.
     *
     * @return InstantiatorInterface
     */
    private function getProxyInstantiator()
    {
        if (!$this->proxyInstantiator) {
            $this->proxyInstantiator = new RealServiceInstantiator();
        }

        return $this->proxyInstantiator;
    }

    private function callMethod($service, $call)
    {
        $services = self::getServiceConditionals($call[1]);

        foreach ($services as $s) {
            if (!$this->has($s)) {
                return;
            }
        }

        call_user_func_array(array($service, $call[0]), $this->resolveServices($this->getParameterBag()->unescapeValue($this->getParameterBag()->resolveValue($call[1]))));
    }

    /**
     * Shares a given service in the container.
     *
     * @param Definition  $definition
     * @param mixed       $service
     * @param string|null $id
     */
    private function shareService(Definition $definition, $service, $id)
    {
        if (null !== $id && $definition->isShared()) {
            $this->services[strtolower($id)] = $service;
        }
    }

    private function getExpressionLanguage()
    {
        if (null === $this->expressionLanguage) {
            if (!class_exists('Symfony\Component\ExpressionLanguage\ExpressionLanguage')) {
                throw new RuntimeException('Unable to use expressions as the Symfony ExpressionLanguage component is not installed.');
            }
            $this->expressionLanguage = new ExpressionLanguage(null, $this->expressionLanguageProviders);
        }

        return $this->expressionLanguage;
    }
}
