Merge pull request #9 from young-steveo/conveyor

Initial, broken, untested CQRS implementation

src/Cabinet/Container.php

@@ -71,9 +71,7 @@ public function service(string $serviceName, string|null $implementation = null)
         if ($implementation === null) {
             $implementation = $serviceName;
         }
-        $this->factory($serviceName, function (Container $container) use ($implementation) {
-            return $container->resolver->resolve($implementation);
-        });
+        $this->factory($serviceName, $this->simpleFactory($implementation));
     }
 
     /**
@@ -129,9 +127,7 @@ public function instance(string $serviceName, mixed $instance): void
      */
     public function prototype(string $serviceName): void
     {
-        $this->prototypeFactory($serviceName, function (Container $container) use ($serviceName) {
-            return $container->resolver->resolve($serviceName);
-        });
+        $this->prototypeFactory($serviceName, $this->simpleFactory($serviceName));
     }
 
     /**
@@ -183,6 +179,14 @@ public function middleware(string $serviceName, Progression $middleware): void
         $this->middlewares[$serviceName] = $this->middlewares[$serviceName]->add($middleware);
     }
 
+    /**
+     * @param class-string $serviceName
+     */
+    protected function simpleFactory(string $serviceName): \Closure
+    {
+        return fn(Container $container) => $container->resolver->resolve($serviceName);
+    }
+
     /**
      * ArrayAccess methods
      */
@@ -227,7 +231,6 @@ public function offsetUnset($offset): void
      *
      * @param class-string $offset
      * @throws Error\InvalidKey
-     * @throws Error\OutOfBounds
      */
     public function offsetGet($offset): mixed
     {
@@ -236,11 +239,9 @@ public function offsetGet($offset): mixed
         }
 
         // Provide the instance.
-        $provider = $this->providers[$offset] ?? new NullProvider();
+        $provider = $this->providers[$offset] ?? PrototypeProvider::fromFactory($this->simpleFactory($offset));
+
         $instance = $provider($this);
-        if (!$instance) {
-            throw new Error\OutOfBounds("No entry was found for this identifier: $offset");
-        }
 
         // Apply decorators.
         if (isset($this->decorators[$offset])) {

src/Cabinet/PrototypeProvider.php

@@ -24,7 +24,7 @@ public static function fromFactory(\Closure $factory): self
     /**
      * Provide a service from the factory.
      */
-    public function __invoke(Container $container): object|null
+    public function __invoke(Container $container): object
     {
         return ($this->factory)($container);
     }

src/Cabinet/Provider.php

@@ -9,5 +9,5 @@ abstract class Provider
     /**
      * Invoking the provider should return the service.
      */
-    abstract public function __invoke(Container $container): object|null;
+    abstract public function __invoke(Container $container): object;
 }

src/Cabinet/SimpleProvider.php

@@ -29,7 +29,7 @@ public static function fromFactory(\Closure $factory): static
     /**
      * Provide a service from the factory.
      */
-    public function __invoke(Container $container): object|null
+    public function __invoke(Container $container): object
     {
         if (!isset($this->service)) {
             $this->service = ($this->factory)($container);

src/Conveyor/Bus.php

@@ -0,0 +1,16 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Arcanum\Conveyor;
+
+interface Bus
+{
+    /**
+     * Dispatch an object to a handler.
+     *
+     * The object to be dispatched should be a simple DTO, and the
+     * return value should be a simple DTO.
+     */
+    public function dispatch(object $object): object;
+}

src/Conveyor/DTO.php

@@ -0,0 +1,56 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Arcanum\Conveyor;
+
+/**
+ * DTO validates that an object is a simple DTO.
+ */
+final class DTO implements Validator
+{
+    /**
+     * Validate a DTO.
+     */
+    public function validate(object $object): void
+    {
+        $image = new \ReflectionClass($object);
+        $name = $image->getName();
+
+        if (!$image->isInstantiable()) {
+            throw new InvalidDTO("$name is not instantiable.");
+        }
+
+        if (!$image->isFinal()) {
+            throw new InvalidDTO("$name is not final.");
+        }
+
+        $properties = $image->getProperties();
+
+        foreach ($properties as $property) {
+            if (!$property->isPublic()) {
+                $propertyName = $property->getName();
+                throw new InvalidDTO("$name has non-public property $propertyName.");
+            }
+
+            if ($property->isStatic()) {
+                $propertyName = $property->getName();
+                throw new InvalidDTO("$name has static property $propertyName.");
+            }
+
+            if (!$property->isReadOnly()) {
+                $propertyName = $property->getName();
+                throw new InvalidDTO("$name has non-read-only property $propertyName.");
+            }
+        }
+
+        $methods = $image->getMethods();
+
+        foreach ($methods as $method) {
+            if ($method->isPublic()) {
+                $methodName = $method->getName();
+                throw new InvalidDTO("$name has public method $methodName.");
+            }
+        }
+    }
+}

src/Conveyor/EmptyDTO.php

@@ -0,0 +1,12 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Arcanum\Conveyor;
+
+/**
+ * Empty is a DTO that has no data.
+ */
+final class EmptyDTO
+{
+}

src/Conveyor/InvalidDTO.php

@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Arcanum\Conveyor;
+
+final class InvalidDTO extends \InvalidArgumentException
+{
+    public function __construct(string $message = '', int $code = 0, \Throwable $previous = null)
+    {
+        parent::__construct("Invalid DTO: $message", $code, $previous);
+    }
+}

src/Conveyor/StrictBus.php

@@ -0,0 +1,51 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Arcanum\Conveyor;
+
+use Arcanum\Cabinet\Container;
+
+class StrictBus extends SwiftBus
+{
+    /**
+     * @var Validator[]
+     */
+    protected array $validators;
+
+    /**
+     * StrictBus
+     *
+     * This bus validates that the object being dispatched passes the validators
+     * and that the response from the handler passes the validators.
+     */
+    public function __construct(protected Container $container, Validator ...$validators)
+    {
+        parent::__construct($container);
+        $this->validators = $validators;
+    }
+
+    /**
+     * Dispatch an object to a handler.
+     */
+    public function dispatch(object $object): object
+    {
+        $this->validateObject($object);
+        $response = parent::dispatch($object);
+        $this->validateObject($response);
+        return $response;
+    }
+
+    /**
+     * Validate that an object is a simple DTO.
+     *
+     * A simple DTO is a class that is final, has only public, non-static,
+     * read-only properties, and has no public methods.
+     */
+    protected function validateObject(object $object): void
+    {
+        foreach ($this->validators as $validator) {
+            $validator->validate($object);
+        }
+    }
+}

src/Conveyor/SwiftBus.php

@@ -0,0 +1,46 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Arcanum\Conveyor;
+
+use Arcanum\Cabinet\Container;
+
+class SwiftBus implements Bus
+{
+    public function __construct(protected Container $container)
+    {
+    }
+
+    /**
+     * Dispatch an object to a handler.
+     */
+    public function dispatch(object $object): object
+    {
+        return $this->handlerFor($object)($object) ?? new EmptyDTO();
+    }
+
+    /**
+     * Get the handler for an object.
+     *
+     * SwiftBus assumes that the handler is a callable.
+     */
+    protected function handlerFor(object $object): callable
+    {
+        /** @var callable */
+        return $this->container->get($this->handlerNameFor($object));
+    }
+
+    /**
+     * Get the handler name for an object.
+     *
+     * This is the class name of the object with the suffix "Handler".
+     *
+     * @return class-string
+     */
+    protected function handlerNameFor(object $object): string
+    {
+        /** @var class-string */
+        return get_class($object) . 'Handler';
+    }
+}

src/Conveyor/Validator.php

@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Arcanum\Conveyor;
+
+interface Validator
+{
+    /**
+     * Validate an object
+     */
+    public function validate(object $object): void;
+}