Auto inject implementation of interface (must tagged with "implementation_inject").

ImplementationInjectPass.php

<?php
/**
 * @author: shengjie
 * @date: 24/07/15 15:33
 * @file: ImplementationInjectPass.php
 */

namespace AppBundle\DependencyInjection;


use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\DependencyInjection\Definition;
/**
 * Example
 * In one bundle:
 * services:
 *    id: my_service
 *    class: MyServiceInterface
 *    tags:
 *      - {name: "implementation_inject"}
 * 
 * 
 * In another bundle:
 * services:
 *    id: my_service_implementation_name_does_not_matter
 *    class: MyServiceImplNameDoesNotMatter //This class implements interface MyServiceInterface
 * 
 * the result will be "my_service" became an alias for service "my_service_implementation_name_does_not_matter"
 */
class ImplementationInjectPass implements CompilerPassInterface
{

    /**
     * You can modify the container here before it is dumped to PHP code.
     * @param ContainerBuilder $container
     * @throws \Exception
     * @api
     */
    public function process(ContainerBuilder $container)
    {
        $services = $container->findTaggedServiceIds("implementation_inject");
        $definitions = $container->getDefinitions();

        foreach ($services as $id => $tags) {
            $injectDef = $container->getDefinition($id);
            $interface = $injectDef->getClass();

            /** @var Definition[] $impls */
            $impls = [];

            foreach ($definitions as $implId => $def) {
                if ($def->isPublic() && !$def->isAbstract() && $id != $implId) {
                    $class = $def->getClass();
                    if ($class && is_subclass_of($class, $interface)) $impls[] = $implId;
                }
            }

            if (count($impls) > 1) throw new \Exception(
                "Multiple implementation for interface $interface found:"
                . implode(",", $impls)//array_map
            );

            if (count($impls) == 0) throw new \Exception("No implementation for interface $interface found!");


            $container->removeDefinition($id);
            $container->setAlias($id, $impls[0]);
        }
    }
}