Support no memory for OpenAIChat

Author: intitni

Tool/Sources/LangChain/Agents/FunctionCallingChatAgent.swift

@@ -76,7 +76,6 @@ public class FunctionCallingChatAgent<Output: AgentOutputParsable & Decodable>:
 
     public init(
         configuration: ChatGPTConfiguration = UserPreferenceChatGPTConfiguration(),
-        memory: ChatGPTMemory = ConversationChatGPTMemory(systemPrompt: ""),
         tools: [AgentTool] = [],
         endFunction: EndFunction
     ) {
@@ -92,7 +91,7 @@ public class FunctionCallingChatAgent<Output: AgentOutputParsable & Decodable>:
                 configuration: configuration.overriding {
                     $0.runFunctionsAutomatically = false
                 },
-                memory: memory,
+                memory: nil,
                 functionProvider: functionProvider,
                 stream: false
             ),
@@ -158,7 +157,7 @@ public class FunctionCallingChatAgent<Output: AgentOutputParsable & Decodable>:
     }
 
     public func parseOutput(_ message: ChatMessage) async -> AgentNextStep<Output> {
-        if message.role == .function, let functionCall = message.functionCall {
+        if message.role == .assistant, let functionCall = message.functionCall {
             if let function = functionProvider.functionTools.first(where: {
                 $0.name == functionCall.name
             }) {

Tool/Sources/LangChain/ChatModel/OpenAIChat.swift

@@ -3,13 +3,13 @@ import OpenAIService
 
 public struct OpenAIChat: ChatModel {
     public var configuration: ChatGPTConfiguration
-    public var memory: ChatGPTMemory
+    public var memory: ChatGPTMemory?
     public var functionProvider: ChatGPTFunctionProvider
     public var stream: Bool
 
     public init(
         configuration: ChatGPTConfiguration = UserPreferenceChatGPTConfiguration(),
-        memory: ChatGPTMemory = ConversationChatGPTMemory(systemPrompt: ""),
+        memory: ChatGPTMemory? = ConversationChatGPTMemory(systemPrompt: ""),
         functionProvider: ChatGPTFunctionProvider = NoChatGPTFunctionProvider(),
         stream: Bool
     ) {
@@ -24,6 +24,8 @@ public struct OpenAIChat: ChatModel {
         stops: [String],
         callbackManagers: [CallbackManager]
     ) async throws -> ChatMessage {
+        let memory = memory ?? EmptyChatGPTMemory()
+        
         let service = ChatGPTService(
             memory: memory,
             configuration: configuration,