Laravel 예제에 대한 자세한 설명: 컨테이너, 제어 반전 및 종속성 주입

# public/index.php
$app = require_once __DIR__.'/../bootstrap/app.php';
# bootstrap/app.php
$app = new Illuminate\Foundation\Application(
    $_ENV['APP_BASE_PATH'] ?? dirname(__DIR__)
);

// namespace Illuminate\Foundation\Application
public function __construct($basePath = null)
{
    if ($basePath) {
        $this->setBasePath($basePath);
    }
    $this->registerBaseBindings();
    $this->registerBaseServiceProviders();
    $this->registerCoreContainerAliases();
}
    
protected function registerBaseBindings()
{
    static::setInstance($this);
    $this->instance('app', $this);
    $this->instance(Container::class, $this);
    /* ... ... */
}
protected function registerBaseServiceProviders()
{
    $this->register(new EventServiceProvider($this));
    $this->register(new LogServiceProvider($this));
    $this->register(new RoutingServiceProvider($this));
}
public function registerCoreContainerAliases()
{
    foreach ([
        'app' => [self::class, \Illuminate\Contracts\Container\Container::class, \Illuminate\Contracts\Foundation\Application::class, \Psr\Container\ContainerInterface::class],
        /* ... ...*/
        'db' => [\Illuminate\Database\DatabaseManager::class, \Illuminate\Database\ConnectionResolverInterface::class],
        'db.connection' => [\Illuminate\Database\Connection::class, \Illuminate\Database\ConnectionInterface::class],
        /* ... ... */
        'request' => [\Illuminate\Http\Request::class, \Symfony\Component\HttpFoundation\Request::class],
        'router' => [\Illuminate\Routing\Router::class, \Illuminate\Contracts\Routing\Registrar::class, \Illuminate\Contracts\Routing\BindingRegistrar::class],
        /* ... ... */
    ] as $key => $aliases) {
        foreach ($aliases as $alias) {
            $this->alias($key, $alias);
        }
    }
}
// namespace Illuminate\Container\Container
public function alias($abstract, $alias)
{
    if ($alias === $abstract) {
        throw new LogicException("[{$abstract}] is aliased to itself.");
    }
    $this->aliases[$alias] = $abstract;
    $this->abstractAliases[$abstract][] = $alias;
}

// namespace Illuminate\Foundation\Application
public function register($provider, $force = false)
{
    if (($registered = $this->getProvider($provider)) && ! $force) {
        return $registered;
    }
    if (is_string($provider)) {
        $provider = $this->resolveProvider($provider);
    }
    $provider->register();
    if (property_exists($provider, 'bindings')) {
        foreach ($provider->bindings as $key => $value) {
            $this->bind($key, $value);
        }
    }
    if (property_exists($provider, 'singletons')) {
        foreach ($provider->singletons as $key => $value) {
            $this->singleton($key, $value);
        }
    }
    $this->markAsRegistered($provider);
    if ($this->isBooted()) {
        $this->bootProvider($provider);
    }
    return $provider;
}

// namespace Illuminate\Log\LogServiceProvider
public function register()
{
    $this->app->singleton('log', function ($app) {
        return new LogManager($app);
    });
}

$app->bindings['log'] = [
    'concrete' => 'Illuminate\Log\LogManager {#162}',
    'shared' => true,
];

// namespace Illuminate\Support\Facades\Log
class Log extends Facade
{
    protected static function getFacadeAccessor()
    {
        return 'log';
    }
}
// namespace Illuminate\Support\Facades\Facade
public static function __callStatic($method, $args)
{
    $instance = static::getFacadeRoot();
    /* ... ... */
    return $instance->$method(...$args);
}
public static function getFacadeRoot()
{
    return static::resolveFacadeInstance(static::getFacadeAccessor());
}
protected static function resolveFacadeInstance($name)
{
    if (is_object($name)) {
        return $name;
    }
    if (isset(static::$resolvedInstance[$name])) {
        return static::$resolvedInstance[$name];
    }
    if (static::$app) {
        return static::$resolvedInstance[$name] = static::$app[$name];
    }
}

// namespace Illuminate\Container
public function offsetGet($key)
{
    return $this->make($key);
}
public function make($abstract, array $parameters = [])
{
    return $this->resolve($abstract, $parameters);
}
protected function resolve($abstract, $parameters = [], $raiseEvents = true)
{
    /* ... ... */
    $this->with[] = $parameters;
    if (is_null($concrete)) {
        $concrete = $this->getConcrete($abstract);
    }
    if ($this->isBuildable($concrete, $abstract)) {
        $object = $this->build($concrete);
    } else {
        $object = $this->make($concrete);
    }
    /* ... ... */
    $this->resolved[$abstract] = true;
    array_pop($this->with);
    return $object;
}
protected function getConcrete($abstract)
{
    if (isset($this->bindings[$abstract])) {
        return $this->bindings[$abstract]['concrete'];
    }
    return $abstract;
}
protected function isBuildable($concrete, $abstract)
{
    return $concrete === $abstract || $concrete instanceof Closure;
}
public function build($concrete)
{
    if ($concrete instanceof Closure) {
        return $concrete($this, $this->getLastParameterOverride());
    }
    /* ... ... */
}
protected function getLastParameterOverride()
{
    return count($this->with) ? end($this->with) : [];
}

// namespace bootstrap/app.php
$app->singleton(
    Illuminate\Contracts\Http\Kernel::class,
    App\Http\Kernel::class
);
$app->singleton(
    Illuminate\Contracts\Console\Kernel::class,
    App\Console\Kernel::class
);
$app->singleton(
    Illuminate\Contracts\Debug\ExceptionHandler::class,
    App\Exceptions\Handler::class
);
// public/index.php
$kernel = $app->make(Illuminate\Contracts\Http\Kernel::class);
$response = $kernel->handle(
    $request = Request::capture()
)->send();
$kernel->terminate($request, $response);

namespace Illuminate\Foundation\Http
use Illuminate\Contracts\Debug\ExceptionHandler
public function handle($request)
{
    try {
        $request->enableHttpMethodParameterOverride();
        $response = $this->sendRequestThroughRouter($request);
    } catch (Throwable $e) {
        $this->reportException($e);
        $response = $this->renderException($request, $e);
    }
    $this->app['events']->dispatch(
        new RequestHandled($request, $response)
    );
    return $response;
}
// 上报错误
protected function reportException(Throwable $e)
{
    $this->app[ExceptionHandler::class]->report($e);
}
// 渲染错误信息    
protected function renderException($request, Throwable $e)
{
    return $this->app[ExceptionHandler::class]->render($request, $e);
}

// namespace Illuminate\Foundation\Http\Kernel
protected $bootstrappers = [
    \Illuminate\Foundation\Bootstrap\LoadEnvironmentVariables::class,
    \Illuminate\Foundation\Bootstrap\LoadConfiguration::class,
    \Illuminate\Foundation\Bootstrap\HandleExceptions::class,
    \Illuminate\Foundation\Bootstrap\RegisterFacades::class,
    \Illuminate\Foundation\Bootstrap\RegisterProviders::class,
    \Illuminate\Foundation\Bootstrap\BootProviders::class,
];
protected function sendRequestThroughRouter($request)
{
    /* ... ... */
    $this->bootstrap();
    /* ... ... */
}
public function bootstrap()
{
    if (! $this->app->hasBeenBootstrapped()) {
        $this->app->bootstrapWith($this->bootstrappers());
    }
}
// namespace Illuminate\Foundation\Application
public function bootstrapWith(array $bootstrappers)
{
    $this->hasBeenBootstrapped = true;
    foreach ($bootstrappers as $bootstrapper) {
        $this['events']->dispatch('bootstrapping: '.$bootstrapper, [$this]);
        $this->make($bootstrapper)->bootstrap($this);
        $this['events']->dispatch('bootstrapped: '.$bootstrapper, [$this]);
    }
}

// namespace Illuminate\Foundation\Bootstrap\HandleExceptions
public function bootstrap(Application $app)
{
    /* ... ... */
    $this->app = $app;
    error_reporting(-1);
    set_error_handler([$this, 'handleError']);
    set_exception_handler([$this, 'handleException']);
    register_shutdown_function([$this, 'handleShutdown']);
    /* ... ... */
}
public function handleError($level, $message, $file = '', $line = 0, $context = [])
{
    if (error_reporting() & $level) {
        /* ... ... */
        throw new ErrorException($message, 0, $level, $file, $line);
    }
}
public function handleException(Throwable $e)
{
    /* ... ... */
        $this->getExceptionHandler()->report($e);
    /* ... ... */
}
public function handleShutdown()
{
    if (! is_null($error = error_get_last()) && $this->isFatal($error['type'])) {
        $this->handleException($this->fatalErrorFromPhpError($error, 0));
    }
}
protected function getExceptionHandler()
{
    return $this->app->make(\Illuminate\Contracts\Debug\ExceptionHandler::class);
}

// namespace Illuminate\Foundation\Bootstrap\RegisterFAcades
public function bootstrap(Application $app)
{
    Facade::clearResolvedInstances();
    Facade::setFacadeApplication($app);
    AliasLoader::getInstance(array_merge(
        $app->make('config')->get('app.aliases', []),
        $app->make(PackageManifest::class)->aliases()
    ))->register();
}

// namespace Illuminate\Foundation\Bootstrap\RegisterProviders
public function bootstrap(Application $app)
{
    $app->registerConfiguredProviders();
}
public function registerConfiguredProviders()
{
    $providers = Collection::make($this->make('config')->get('app.providers'))
                    ->partition(function ($provider) {
                        return strpos($provider, 'Illuminate\\') === 0;
                    });
    $providers->splice(1, 0, [$this->make(PackageManifest::class)->providers()]);
    (new ProviderRepository($this, new Filesystem, $this->getCachedServicesPath()))
                ->load($providers->collapse()->toArray());
}

// namespace Illuminate\Foundation\Http\Kernel
protected function sendRequestThroughRouter($request)
{
    /* ... ... */
    return (new Pipeline($this->app))
                ->send($request)
                ->through($this->app->shouldSkipMiddleware() ? [] : $this->middleware)
                ->then($this->dispatchToRouter());
}
protected function dispatchToRouter()
{
    return function ($request) {
        $this->app->instance('request', $request);
        
        return $this->router->dispatch($request);
    };
}
// namespace Illuminate\Routing\Router
public function dispatch(Request $request)
{
    $this->currentRequest = $request;
    return $this->dispatchToRoute($request);
}
public function dispatchToRoute(Request $request)
{
    return $this->runRoute($request, $this->findRoute($request));
}
protected function runRoute(Request $request, Route $route)
{
    /* ... ... */
    return $this->prepareResponse($request,
        $this->runRouteWithinStack($route, $request)
    );
}
protected function runRouteWithinStack(Route $route, Request $request)
{
    /* ... ... */   
    return (new Pipeline($this->container))
                    ->send($request)
                    ->through($middleware)
                    ->then(function ($request) use ($route) {
                        return $this->prepareResponse(
                            $request, $route->run()
                        );
                    });
}

// namespace Illuminate\Routing\Router
public function run()
{
    $this->container = $this->container ?: new Container;
    try {
        if ($this->isControllerAction()) {
            return $this->runController();
        }
        return $this->runCallable();
    } catch (HttpResponseException $e) {
        return $e->getResponse();
    }
}
protected function runController()
{
    return $this->controllerDispatcher()->dispatch(
        $this, $this->getController(), $this->getControllerMethod()
    );
}
protected function runCallable()
{
    /* ... ... */
    return $callable(...array_values($this->resolveMethodDependencies(
        $this->parametersWithoutNulls(), new ReflectionFunction($callable)
    )));
}
// namespace Illuminate\Routing\ControllerDispatcher
public function dispatch(Route $route, $controller, $method)
{
    $parameters = $this->resolveClassMethodDependencies(
        $route->parametersWithoutNulls(), $controller, $method
    );
    /* ... ... */
}
// namespace Illuminate\Routing\RouteDependencyResolverTrait
protected function resolveClassMethodDependencies(array $parameters, $instance, $method)
{
    /* ... ... */
    return $this->resolveMethodDependencies(
        $parameters, new ReflectionMethod($instance, $method)
    );
}
public function resolveMethodDependencies(array $parameters, ReflectionFunctionAbstract $reflector)
{
    /* ... ... */
    foreach ($reflector->getParameters() as $key => $parameter) {
        $instance = $this->transformDependency($parameter, $parameters, $skippableValue);
        /* ... ... */
    }
    return $parameters;
}
protected function transformDependency(ReflectionParameter $parameter, $parameters, $skippableValue)
{
    $className = Reflector::getParameterClassName($parameter);
    if ($className && ! $this->alreadyInParameters($className, $parameters)) {
        return $parameter->isDefaultValueAvailable() ? null : $this->container->make($className);
    }
    return $skippableValue;
}

// namespace Illuminate\Container\Container
public function build($concrete)
{
    /* ... ... */
    try {
        $reflector = new ReflectionClass($concrete);
    } catch (ReflectionException $e) {
        throw new BindingResolutionException("Target class [$concrete] does not exist.", 0, $e);
    }
    if (! $reflector->isInstantiable()) {
        return $this->notInstantiable($concrete);
    }
    $this->buildStack[] = $concrete;
    $constructor = $reflector->getConstructor();
    if (is_null($constructor)) {
        array_pop($this->buildStack);
        return new $concrete;
    }
    $dependencies = $constructor->getParameters();
    try {
        $instances = $this->resolveDependencies($dependencies);
    } catch (BindingResolutionException $e) {
        array_pop($this->buildStack);
        throw $e;
    }
    array_pop($this->buildStack);
    return $reflector->newInstanceArgs($instances);
}
protected function resolveDependencies(array $dependencies)
{
    $results = [];
    foreach ($dependencies as $dependency) {
        if ($this->hasParameterOverride($dependency)) {
            $results[] = $this->getParameterOverride($dependency);
            continue;
        }
        $result = is_null(Util::getParameterClassName($dependency))
                        ? $this->resolvePrimitive($dependency)
                        : $this->resolveClass($dependency);
        if ($dependency->isVariadic()) {
            $results = array_merge($results, $result);
        } else {
            $results[] = $result;
        }
    }
    return $results;
}