[BC BREAK] MessageBag does not depend on \ArrayObject anymore

src/Bridge/Meta/LlamaPromptConverter.php

@@ -19,7 +19,7 @@ public function convertToPrompt(MessageBag $messageBag): string
         $messages = [];
 
         /** @var UserMessage|SystemMessage|AssistantMessage $message */
-        foreach ($messageBag->getIterator() as $message) {
+        foreach ($messageBag->getMessages() as $message) {
             $messages[] = self::convertMessage($message);
         }
 

src/Chain/ToolBox/ChainProcessor.php

@@ -45,11 +45,11 @@ public function processOutput(Output $output): void
 
         while ($output->response instanceof ToolCallResponse) {
             $toolCalls = $output->response->getContent();
-            $messages[] = Message::ofAssistant(toolCalls: $toolCalls);
+            $messages->add(Message::ofAssistant(toolCalls: $toolCalls));
 
             foreach ($toolCalls as $toolCall) {
                 $result = $this->toolBox->execute($toolCall);
-                $messages[] = Message::ofToolCall($toolCall, $result);
+                $messages->add(Message::ofToolCall($toolCall, $result));
             }
 
             $output->response = $this->chain->call($messages, $output->options);

src/Model/Message/MessageBag.php

@@ -4,19 +4,34 @@
 
 namespace PhpLlm\LlmChain\Model\Message;
 
-/**
- * @template-extends \ArrayObject<int, MessageInterface>
- */
-final class MessageBag extends \ArrayObject implements \JsonSerializable
+final class MessageBag implements \Countable, \JsonSerializable
 {
+    /**
+     * @var MessageInterface[]
+     */
+    private array $messages;
+
     public function __construct(MessageInterface ...$messages)
     {
-        parent::__construct(array_values($messages));
+        $this->messages = array_values($messages);
+    }
+
+    public function add(MessageInterface $message): void
+    {
+        $this->messages[] = $message;
+    }
+
+    /**
+     * @return MessageInterface[]
+     */
+    public function getMessages(): array
+    {
+        return $this->messages;
     }
 
     public function getSystemMessage(): ?SystemMessage
     {
-        foreach ($this as $message) {
+        foreach ($this->messages as $message) {
             if ($message instanceof SystemMessage) {
                 return $message;
             }
@@ -28,43 +43,41 @@ public function getSystemMessage(): ?SystemMessage
     public function with(MessageInterface $message): self
     {
         $messages = clone $this;
-        $messages->append($message);
+        $messages->add($message);
 
         return $messages;
     }
 
     public function merge(MessageBag $messageBag): self
     {
         $messages = clone $this;
-        $messages->exchangeArray(array_merge($messages->getArrayCopy(), $messageBag->getArrayCopy()));
+        $messages->messages = array_merge($messages->messages, $messageBag->messages);
 
         return $messages;
     }
 
     public function withoutSystemMessage(): self
     {
         $messages = clone $this;
-        $messages->exchangeArray(
-            array_values(array_filter(
-                $messages->getArrayCopy(),
-                static fn (MessageInterface $message) => !$message instanceof SystemMessage,
-            ))
-        );
+        $messages->messages = array_values(array_filter(
+            $messages->messages,
+            static fn (MessageInterface $message) => !$message instanceof SystemMessage,
+        ));
 
         return $messages;
     }
 
     public function prepend(MessageInterface $message): self
     {
         $messages = clone $this;
-        $messages->exchangeArray(array_merge([$message], $messages->getArrayCopy()));
+        $messages->messages = array_merge([$message], $messages->messages);
 
         return $messages;
     }
 
     public function containsImage(): bool
     {
-        foreach ($this as $message) {
+        foreach ($this->messages as $message) {
             if ($message instanceof UserMessage && $message->hasImageContent()) {
                 return true;
             }
@@ -73,11 +86,16 @@ public function containsImage(): bool
         return false;
     }
 
+    public function count(): int
+    {
+        return count($this->messages);
+    }
+
     /**
      * @return MessageInterface[]
      */
     public function jsonSerialize(): array
     {
-        return $this->getArrayCopy();
+        return $this->messages;
     }
 }

tests/Bridge/Meta/LlamaPromptConverterTest.php

@@ -26,7 +26,7 @@ public function convertMessages(): void
     {
         $messageBag = new MessageBag();
         foreach (self::provideMessages() as $message) {
-            $messageBag->append($message[1]);
+            $messageBag->add($message[1]);
         }
 
         self::assertSame(<<<EXPECTED

tests/Model/Message/MessageBagTest.php

@@ -70,7 +70,7 @@ public function with(): void
         self::assertCount(3, $messageBag);
         self::assertCount(4, $newMessageBag);
 
-        $newMessageFromBag = $newMessageBag[3];
+        $newMessageFromBag = $newMessageBag->getMessages()[3];
 
         self::assertInstanceOf(AssistantMessage::class, $newMessageFromBag);
         self::assertSame('It is time to wake up.', $newMessageFromBag->content);
@@ -91,7 +91,7 @@ public function merge(): void
 
         self::assertCount(4, $messageBag);
 
-        $messageFromBag = $messageBag[3];
+        $messageFromBag = $messageBag->getMessages()[3];
 
         self::assertInstanceOf(AssistantMessage::class, $messageFromBag);
         self::assertSame('It is time to wake up.', $messageFromBag->content);
@@ -111,7 +111,7 @@ public function withoutSystemMessage(): void
         self::assertCount(3, $messageBag);
         self::assertCount(2, $newMessageBag);
 
-        $messageFromNewBag = $newMessageBag[0];
+        $messageFromNewBag = $newMessageBag->getMessages()[0];
 
         self::assertInstanceOf(AssistantMessage::class, $messageFromNewBag);
         self::assertSame('It is time to sleep.', $messageFromNewBag->content);
@@ -131,14 +131,14 @@ public function prepend(): void
         self::assertCount(2, $messageBag);
         self::assertCount(3, $newMessageBag);
 
-        $newMessageBagMessage = $newMessageBag[0];
+        $newMessageBagMessage = $newMessageBag->getMessages()[0];
 
         self::assertInstanceOf(SystemMessage::class, $newMessageBagMessage);
         self::assertSame('My amazing system prompt.', $newMessageBagMessage->content);
     }
 
     #[Test]
-    public function containsImageWithoutImage(): void
+    public function containsImageReturnsFalseWithoutImage(): void
     {
         $messageBag = new MessageBag(
             Message::ofAssistant('It is time to sleep.'),
@@ -149,7 +149,7 @@ public function containsImageWithoutImage(): void
     }
 
     #[Test]
-    public function containsImageWithImage(): void
+    public function containsImageReturnsTrueWithImage(): void
     {
         $messageBag = new MessageBag(
             Message::ofAssistant('It is time to sleep.'),