Additional functionality for supporting classes.

src/Domain/ChainRepository.php

@@ -0,0 +1,107 @@
+<?php
+
+declare(strict_types=1);
+
+namespace GeekCell\Ddd\Domain;
+
+use Assert;
+use GeekCell\Ddd\Contracts\Domain\Paginator;
+use GeekCell\Ddd\Contracts\Domain\Repository as RepositoryInterface;
+use Traversable;
+
+abstract class ChainRepository implements RepositoryInterface
+{
+    /**
+     * @var array<class-string<RepositoryInterface>, RepositoryInterface>
+     */
+    private array $repositories;
+
+    /**
+     * @var class-string<RepositoryInterface>
+     */
+    private string $primaryRepositoryKey;
+
+    /**
+     * ChainRepository constructor.
+     */
+    public function __construct(RepositoryInterface ...$repositories)
+    {
+        foreach ($repositories as $repository) {
+            $this->repositories[get_class($repository)] = $repository;
+        }
+
+        // Select the first repository as primary by default
+        $firstRepository = reset($repositories);
+        $this->selectPrimary($firstRepository);
+    }
+
+    /**
+     * Selects the primary repository, which will be used for collection,
+     * pagination and count.
+     *
+     * @param RepositoryInterface $repository
+     *
+     * @throws Assert\AssertionFailedException
+     */
+    protected function selectPrimary(RepositoryInterface $repository): void
+    {
+        $className = get_class($repository);
+        Assert\Assertion::keyExists($this->repositories, $className);
+
+        $this->primaryRepositoryKey = $className;
+    }
+
+    /**
+     * Returns the currently selected primary repository.
+     *
+     * @return RepositoryInterface
+     */
+    protected function getPrimary(): RepositoryInterface
+    {
+        return $this->repositories[$this->primaryRepositoryKey];
+    }
+
+    /**
+     * Delegate operation to the currently selected primary repository.
+     * For more advanced scenarios, this method can be overridden.
+     *
+     * @inheritDoc
+     */
+    public function collect(): Collection
+    {
+        return $this->getPrimary()->collect();
+    }
+
+    /**
+     * Delegate operation to the currently selected primary repository.
+     * For more advanced scenarios, this method can be overridden.
+     *
+     * @inheritDoc
+     */
+    public function paginate(int $itemsPerPage, int $currentPage = 1): Paginator
+    {
+        return $this->getPrimary()->paginate($itemsPerPage, $currentPage);
+    }
+
+    /**
+     * Delegate operation to the currently selected primary repository.
+     * For more advanced scenarios, this method can be overridden.
+     *
+     * @inheritDoc
+     */
+    public function count(): int
+    {
+        return $this->getPrimary()->count();
+    }
+
+    /**
+     * Delegate operation to the currently selected primary repository.
+     * For more advanced scenarios, this method can be overridden.
+     *
+     * @inheritDoc
+     */
+    public function getIterator(): Traversable
+    {
+        return $this->getPrimary()->getIterator();
+    }
+}

src/Domain/Collection.php

@@ -4,36 +4,154 @@
 
 namespace GeekCell\Ddd\Domain;
 
+use ArrayAccess;
 use ArrayIterator;
 use Assert;
 use Countable;
 use IteratorAggregate;
 use Traversable;
 
-class Collection implements Countable, IteratorAggregate
+class Collection implements ArrayAccess, Countable, IteratorAggregate
 {
     /**
      * @template T of object
      * @extends IteratorAggregate<T>
      *
      * @param T[] $items
      * @param class-string<T> $itemType
+     *
+     * @throws Assert\AssertionFailedException
      */
     final public function __construct(
         private readonly array $items = [],
-        ?string $itemType = null,
+        private ?string $itemType = null,
     ) {
         if ($itemType !== null) {
             Assert\Assertion::allIsInstanceOf($items, $itemType);
         }
     }
 
+    /**
+     * Add one or more items to the collection. It **does not** modify the
+     * current collection, but returns a new one.
+     *
+     * @param mixed $item  One or more items to add to the collection.
+     * @return static
+     *
+     * @throws Assert\AssertionFailedException
+     */
+    public function add(mixed $item): static
+    {
+        if (!is_array($item)) {
+            $item = [$item];
+        }
+
+        if ($this->itemType !== null) {
+            Assert\Assertion::allIsInstanceOf($item, $this->itemType);
+        }
+
+        return new static([...$this->items, ...$item], $this->itemType);
+    }
+
+    /**
+     * Filter the collection using the given callback. It **does not** modify
+     * the current collection, but returns a new one.
+     *
+     * @param callable $callback  The callback to use for filtering.
+     * @return static
+     */
+    public function filter(callable $callback): static
+    {
+        return new static(
+            array_filter($this->items, $callback),
+            $this->itemType,
+        );
+    }
+
+    /**
+     * Map the collection using the given callback. It **does not** modify
+     * the current collection, but returns a new one.
+     *
+     * @param callable $callback  The callback to use for mapping.
+     * @param bool $inferTypes    Whether to infer the type of the items in the
+     *                            collection based on the first item in the
+     *                            mapping result. Defaults to `true`.
+     *
+     * @return static
+     */
+    public function map(callable $callback, bool $inferTypes = true): static
+    {
+        $mapResult = array_map($callback, $this->items);
+        $firstItem = reset($mapResult);
+
+        if ($firstItem === false || !is_object($firstItem)) {
+            return new static($mapResult);
+        }
+
+        if ($inferTypes && $this->itemType !== null) {
+            return new static($mapResult, get_class($firstItem));
+        }
+
+        return new static($mapResult);
+    }
+
+    /**
+     * Reduce the collection using the given callback.
+     *
+     * @param callable $callback  The callback to use for reducing.
+     * @param mixed $initial      The initial value to use for reducing.
+     *
+     * @return mixed
+     */
+    public function reduce(callable $callback, mixed $initial = null): mixed
+    {
+        return array_reduce($this->items, $callback, $initial);
+    }
+
     /**
      * @inheritDoc
      */
-    public function getIterator(): Traversable
+    public function offsetExists(mixed $offset): bool
     {
-        return new ArrayIterator($this->items);
+        if (!is_int($offset)) {
+            return false;
+        }
+
+        return isset($this->items[$offset]);
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function offsetGet(mixed $offset): mixed
+    {
+        if (!$this->offsetExists($offset)) {
+            return null;
+        }
+
+        return $this->items[$offset];
+    }
+
+    /**
+     * This method is not supported since it would break the immutability of the
+     * collection.
+     *
+     * @inheritDoc
+     */
+    public function offsetSet(mixed $offset, mixed $value): void
+    {
+        // Unsupported since it would break the immutability of the collection.
+    }
+
+    /**
+     * This method is not supported since it would break the immutability of the
+     * collection.
+     *
+     * @inheritDoc
+     */
+    public function offsetUnset(mixed $offset): void
+    {
+        // Unsupported since it would break the immutability of the collection.
     }
 
     /**
@@ -43,4 +161,12 @@ public function count(): int
     {
         return count($this->items);
     }
+
+    /**
+     * @inheritDoc
+     */
+    public function getIterator(): Traversable
+    {
+        return new ArrayIterator($this->items);
+    }
 }

src/Infrastructure/InMemory/CommandBus.php

@@ -7,7 +7,7 @@
 use GeekCell\Ddd\Contracts\Application\Command;
 use GeekCell\Ddd\Contracts\Application\CommandBus as CommandBusInterface;
 use GeekCell\Ddd\Contracts\Application\CommandHandler;
-use GeekCell\Ddd\Support\Attributes\For\Command as ForCommand;
+use GeekCell\Ddd\Support\Attributes\ForType\Command as ForCommand;
 
 class CommandBus extends AbstractBus implements CommandBusInterface
 {

src/Infrastructure/InMemory/Paginator.php

@@ -4,13 +4,14 @@
 
 namespace GeekCell\Ddd\Infrastructure\InMemory;
 
+use ArrayAccess;
 use EmptyIterator;
 use GeekCell\Ddd\Contracts\Domain\Paginator as PaginatorInterface;
 use GeekCell\Ddd\Domain\Collection;
 use LimitIterator;
 use Traversable;
 
-class Paginator implements PaginatorInterface
+class Paginator implements PaginatorInterface, ArrayAccess
 {
     public function __construct(
         private readonly Collection $collection,
@@ -52,6 +53,57 @@ public function getTotalItems(): int
         return count($this->collection);
     }
 
+    /**
+     * @inheritDoc
+     */
+    public function offsetExists(mixed $offset): bool
+    {
+        if (!is_int($offset)) {
+            return false;
+        }
+
+        return $offset >= 0 && $offset < $this->count();
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function offsetGet(mixed $offset): mixed
+    {
+        if (!$this->offsetExists($offset)) {
+            return null;
+        }
+
+        $realOffset = $offset + $this->getCurrentPage();
+        foreach ($this->getIterator() as $index => $item) {
+            if ($index === $realOffset) {
+                return $item;
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * This method is not supported since it is not appropriate for a paginator.
+     *
+     * @inheritDoc
+     */
+    public function offsetSet(mixed $offset, mixed $value): void
+    {
+        // Unsupported since it is not appropriate for a paginator.
+    }
+
+    /**
+     * This method is not supported since it is not appropriate for a paginator.
+     *
+     * @inheritDoc
+     */
+    public function offsetUnset(mixed $offset): void
+    {
+        // Unsupported since it is not appropriate for a paginator.
+    }
+
     /**
      * @inheritDoc
      */

src/Infrastructure/InMemory/QueryBus.php

@@ -7,7 +7,7 @@
 use GeekCell\Ddd\Contracts\Application\Query;
 use GeekCell\Ddd\Contracts\Application\QueryBus as QueryBusInterface;
 use GeekCell\Ddd\Contracts\Application\QueryHandler;
-use GeekCell\Ddd\Support\Attributes\For\Query as ForQuery;
+use GeekCell\Ddd\Support\Attributes\ForType\Query as ForQuery;
 
 final class QueryBus extends AbstractBus implements QueryBusInterface
 {

src/Support/Attributes/For/Command.php → src/Support/Attributes/ForType/Command.php

@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace GeekCell\Ddd\Support\Attributes\For;
+namespace GeekCell\Ddd\Support\Attributes\ForType;
 
 use Attribute;
 use GeekCell\Ddd\Contracts\Application\Command as CommandInterface;

src/Support/Attributes/For/Query.php → src/Support/Attributes/ForType/Query.php

@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace GeekCell\Ddd\Support\Attributes\For;
+namespace GeekCell\Ddd\Support\Attributes\ForType;
 
 use Attribute;
 use GeekCell\Ddd\Contracts\Application\Query as QueryInterface;