Added response format to the chat completions request body

Author: Recouse

Sources/OpenAI/Chat/ChatCompletionsBody.swift

@@ -64,6 +64,9 @@ public extension ChatCompletions {
         ///
         /// [See more information about frequency and presence penalties.](/docs/api-reference/parameter-details)
         public var frequencyPenalty: Double?
+        /// An object specifying the format that the model must output. Compatible with GPT-4 Turbo and gpt-3.5-turbo-1106.
+        /// Setting `type` to `.jsonObject` enables JSON mode, which guarantees the message the model generates is valid JSON.
+        public var responseFormat: ResponseFormat?
         /// Modify the likelihood of specified tokens appearing in the completion.
         ///
         /// Accepts a json object that maps tokens (specified by their token ID in the tokenizer) to an associated bias value from -100 to 100. Mathematically, the bias is added to the logits generated by the model prior to sampling. The exact effect will vary per model, but values between -1 and 1 should decrease or increase likelihood of selection; values like -100 or 100 should result in a ban or exclusive selection of the relevant token.

Sources/OpenAI/Chat/ChatWrapper.swift

@@ -21,6 +21,7 @@ public struct ChatWrapper {
         maxTokens: Int? = nil,
         presencePenalty: Double? = nil,
         frequencyPenalty: Double? = nil,
+        responseFormat: ResponseFormat? = nil,
         logitBias: [Int: Int]? = nil,
         user: String? = nil
     ) async throws -> ChatCompletions.Response {
@@ -35,6 +36,7 @@ public struct ChatWrapper {
             maxTokens: maxTokens,
             presencePenalty: presencePenalty,
             frequencyPenalty: frequencyPenalty,
+            responseFormat: responseFormat,
             logitBias: logitBias,
             user: user
         )
@@ -58,6 +60,7 @@ public struct ChatWrapper {
         maxTokens: Int? = nil,
         presencePenalty: Double? = nil,
         frequencyPenalty: Double? = nil,
+        responseFormat: ResponseFormat? = nil,
         logitBias: [Int: Int]? = nil,
         user: String? = nil
     ) -> AsyncThrowingStream<ChatCompletions.Response.Chunk, Error> {
@@ -72,6 +75,7 @@ public struct ChatWrapper {
             maxTokens: maxTokens,
             presencePenalty: presencePenalty,
             frequencyPenalty: frequencyPenalty,
+            responseFormat: responseFormat,
             logitBias: logitBias,
             user: user
         )

Sources/OpenAI/Common/ReponseFormat.swift

@@ -0,0 +1,14 @@
+//
+//  ResponseFormat.swift
+//  OpenAI
+//
+//  Created by Firdavs Khaydarov on 27/01/2024.
+//
+
+public struct ResponseFormat: Encodable {
+    public enum `Type`: String, Encodable {
+        case jsonObject = "json_object"
+    }
+    
+    public let type: `Type`
+}