Cache::isSupported()) {
                throw new \Exception('APCu is not enabled, PHP-DI cannot use it as a cache');
            }
            // Wrap the source with the cache decorator
            $source = new SourceCache($source, $this->sourceCacheNamespace);
        }

        $proxyFactory = new ProxyFactory(
            $this->writeProxiesToFile,
            $this->proxyDirectory
        );

        $this->locked = true;

        $containerClass = $this->containerClass;

        if ($this->compileToDirectory) {
            $compiler = new Compiler($proxyFactory);
            $compiledContainerFile = $compiler->compile(
                $source,
                $this->compileToDirectory,
                $containerClass,
                $this->containerParentClass,
                $this->useAutowiring || $this->useAnnotations
            );
            // Only load the file if it hasn't been already loaded
            // (the container can be created multiple times in the same process)
            if (!class_exists($containerClass, false)) {
                require $compiledContainerFile;
            }
        }

        return new $containerClass($source, $proxyFactory, $this->wrapperContainer);
    }

    /**
     * Compile the container for optimum performances.
     *
     * Be aware that the container is compiled once and never updated!
     *
     * Therefore:
     *
     * - in production you should clear that directory every time you deploy
     * - in development you should not compile the container
     *
     * @see https://php-di.org/doc/performances.html
     *
     * @param string $directory Directory in which to put the compiled container.
     * @param string $containerClass Name of the compiled class. Customize only if necessary.
     * @param string $containerParentClass Name of the compiled container parent class. Customize only if necessary.
     */
    public function enableCompilation(
        string $directory,
        string $containerClass = 'CompiledContainer',
        string $containerParentClass = CompiledContainer::class
    ) : self {
        $this->ensureNotLocked();

        $this->compileToDirectory = $directory;
        $this->containerClass = $containerClass;
        $this->containerParentClass = $containerParentClass;

        return $this;
    }

    /**
     * Enable or disable the use of autowiring to guess injections.
     *
     * Enabled by default.
     *
     * @return $this
     */
    public function useAutowiring(bool $bool) : self
    {
        $this->ensureNotLocked();

        $this->useAutowiring = $bool;

        return $this;
    }

    /**
     * Enable or disable the use of annotations to guess injections.
     *
     * Disabled by default.
     *
     * @return $this
     */
    public function useAnnotations(bool $bool) : self
    {
        $this->ensureNotLocked();

        $this->useAnnotations = $bool;

        return $this;
    }

    /**
     * Enable or disable ignoring phpdoc errors (non-existent classes in `@param` or `@var`).
     *
     * @return $this
     */
    public function ignorePhpDocErrors(bool $bool) : self
    {
        $this->ensureNotLocked();

        $this->ignorePhpDocErrors = $bool;

        return $this;
    }

    /**
     * Configure the proxy generation.
     *
     * For dev environment, use `writeProxiesToFile(false)` (default configuration)
     * For production environment, use `writeProxiesToFile(true, 'tmp/proxies')`
     *
     * @see https://php-di.org/doc/lazy-injection.html
     *
     * @param bool $writeToFile If true, write the proxies to disk to improve performances
     * @param string|null $proxyDirectory Directory where to write the proxies
     * @throws InvalidArgumentException when writeToFile is set to true and the proxy directory is null
     * @return $this
     */
    public function writeProxiesToFile(bool $writeToFile, string $proxyDirectory = null) : self
    {
        $this->ensureNotLocked();

        $this->writeProxiesToFile = $writeToFile;

        if ($writeToFile && $proxyDirectory === null) {
            throw new InvalidArgumentException(
                'The proxy directory must be specified if you want to write proxies on disk'
            );
        }
        $this->proxyDirectory = $proxyDirectory;

        return $this;
    }

    /**
     * If PHP-DI's container is wrapped by another container, we can
     * set this so that PHP-DI will use the wrapper rather than itself for building objects.
     *
     * @return $this
     */
    public function wrapContainer(ContainerInterface $otherContainer) : self
    {
        $this->ensureNotLocked();

        $this->wrapperContainer = $otherContainer;

        return $this;
    }

    /**
     * Add definitions to the container.
     *
     * @param string|array|DefinitionSource ...$definitions Can be an array of definitions, the
     *                                                      name of a file containing definitions
     *                                                      or a DefinitionSource object.
     * @return $this
     */
    public function addDefinitions(...$definitions) : self
    {
        $this->ensureNotLocked();

        foreach ($definitions as $definition) {
            if (!is_string($definition) && !is_array($definition) && !($definition instanceof DefinitionSource)) {
                throw new InvalidArgumentException(sprintf(
                    '%s parameter must be a string, an array or a DefinitionSource object, %s given',
                    'ContainerBuilder::addDefinitions()',
                    is_object($definition) ? get_class($definition) : gettype($definition)
                ));
            }

            $this->definitionSources[] = $definition;
        }

        return $this;
    }

    /**
     * Enables the use of APCu to cache definitions.
     *
     * You must have APCu enabled to use it.
     *
     * Before using this feature, you should try these steps first:
     * - enable compilation if not already done (see `enableCompilation()`)
     * - if you use autowiring or annotations, add all the classes you are using into your configuration so that
     *   PHP-DI knows about them and compiles them
     * Once this is done, you can try to optimize performances further with APCu. It can also be useful if you use
     * `Container::make()` instead of `get()` (`make()` calls cannot be compiled so they are not optimized).
     *
     * Remember to clear APCu on each deploy else your application will have a stale cache. Do not enable the cache
     * in development environment: any change you will make to the code will be ignored because of the cache.
     *
     * @see https://php-di.org/doc/performances.html
     *
     * @param string $cacheNamespace use unique namespace per container when sharing a single APC memory pool to prevent cache collisions
     * @return $this
     */
    public function enableDefinitionCache(string $cacheNamespace = '') : self
    {
        $this->ensureNotLocked();

        $this->sourceCache = true;
        $this->sourceCacheNamespace = $cacheNamespace;

        return $this;
    }

    /**
     * Are we building a compiled container?
     */
    public function isCompilationEnabled() : bool
    {
        return (bool) $this->compileToDirectory;
    }

    private function ensureNotLocked()
    {
        if ($this->locked) {
            throw new \LogicException('The ContainerBuilder cannot be modified after the container has been built');
        }
    }
}