symfony/src/Symfony/Component/DependencyInjection/ServiceLocator.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 Psr\Container\ContainerInterface as PsrContainerInterface;
use Symfony\Component\DependencyInjection\Exception\ServiceCircularReferenceException;
use Symfony\Component\DependencyInjection\Exception\ServiceNotFoundException;

/**
 * @author Robin Chalas <robin.chalas@gmail.com>
 * @author Nicolas Grekas <p@tchwork.com>
 */
class ServiceLocator implements PsrContainerInterface
{
    private $factories;
    private $loading = array();
    private $externalId;
    private $container;

    /**
     * @param callable[] $factories
     */
    public function __construct(array $factories)
    {
        $this->factories = $factories;
    }

    /**
     * {@inheritdoc}
     */
    public function has($id)
    {
        return isset($this->factories[$id]);
    }

    /**
     * {@inheritdoc}
     */
    public function get($id)
    {
        if (!isset($this->factories[$id])) {
            throw new ServiceNotFoundException($id, end($this->loading) ?: null, null, array(), $this->createServiceNotFoundMessage($id));
        }

        if (isset($this->loading[$id])) {
            $ids = array_values($this->loading);
            $ids = array_slice($this->loading, array_search($id, $ids));
            $ids[] = $id;

            throw new ServiceCircularReferenceException($id, $ids);
        }

        $this->loading[$id] = $id;
        try {
            return $this->factories[$id]();
        } finally {
            unset($this->loading[$id]);
        }
    }

    public function __invoke($id)
    {
        return isset($this->factories[$id]) ? $this->get($id) : null;
    }

    /**
     * @internal
     */
    public function withContext($externalId, Container $container)
    {
        $locator = clone $this;
        $locator->externalId = $externalId;
        $locator->container = $container;

        return $locator;
    }

    private function createServiceNotFoundMessage($id)
    {
        if ($this->loading) {
            return sprintf('The service "%s" has a dependency on a non-existent service "%s". This locator %s', end($this->loading), $id, $this->formatAlternatives());
        }

        $class = debug_backtrace(DEBUG_BACKTRACE_PROVIDE_OBJECT | DEBUG_BACKTRACE_IGNORE_ARGS, 3);
        $class = isset($class[2]['object']) ? get_class($class[2]['object']) : null;
        $externalId = $this->externalId ?: $class;

        $msg = sprintf('Service "%s" not found: ', $id);

        if (!$this->container) {
            $class = null;
        } elseif ($this->container->has($id) || isset($this->container->getRemovedIds()[$id])) {
            $msg .= 'even though it exists in the app\'s container, ';
        } else {
            try {
                $this->container->get($id);
                $class = null;
            } catch (ServiceNotFoundException $e) {
                if ($e->getAlternatives()) {
                    $msg .= sprintf(' did you mean %s? Anyway, ', $this->formatAlternatives($e->getAlternatives(), 'or'));
                } else {
                    $class = null;
                }
            }
        }
        if ($externalId) {
            $msg .= sprintf('the container inside "%s" is a smaller service locator that %s', $externalId, $this->formatAlternatives());
        } else {
            $msg .= sprintf('the current service locator %s', $this->formatAlternatives());
        }

        if (!$class) {
            // no-op
        } elseif (is_subclass_of($class, ServiceSubscriberInterface::class)) {
            $msg .= sprintf(' Unless you need extra laziness, try using dependency injection instead. Otherwise, you need to declare it using "%s::getSubscribedServices()".', preg_replace('/([^\\\\]++\\\\)++/', '', $class));
        } else {
            $msg .= 'Try using dependency injection instead.';
        }

        return $msg;
    }

    private function formatAlternatives(array $alternatives = null, $separator = 'and')
    {
        $format = '"%s"%s';
        if (null === $alternatives) {
            if (!$alternatives = array_keys($this->factories)) {
                return 'is empty...';
            }
            $format = sprintf('only knows about the %s service%s.', $format, 1 < count($alternatives) ? 's' : '');
        }
        $last = array_pop($alternatives);

        return sprintf($format, $alternatives ? implode('", "', $alternatives) : $last, $alternatives ? sprintf(' %s "%s"', $separator, $last) : '');
    }
}