Add automatic function calling prototype

Examples/GenerativeAICLI/Sources/GenerateContent.swift

@@ -70,9 +70,20 @@ struct GenerateContent: AsyncParsableCommand {
         name: modelNameOrDefault(),
         apiKey: apiKey,
         generationConfig: config,
-        safetySettings: safetySettings
+        safetySettings: safetySettings,
+        tools: [Tool(functionDeclarations: [
+          FunctionDeclaration(
+            name: "get_exchange_rate",
+            description: "Get the exchange rate for currencies between countries",
+            parameters: getExchangeRateSchema(),
+            function: getExchangeRateWrapper
+          ),
+        ])],
+        requestOptions: RequestOptions(apiVersion: "v1beta")
       )
 
+      let chat = model.startChat()
+
       var parts = [ModelContent.Part]()
 
       if let textPrompt = textPrompt {
@@ -96,15 +107,16 @@ struct GenerateContent: AsyncParsableCommand {
       let input = [ModelContent(parts: parts)]
 
       if isStreaming {
-        let contentStream = model.generateContentStream(input)
+        let contentStream = chat.sendMessageStream(input)
         print("Generated Content <streaming>:")
         for try await content in contentStream {
           if let text = content.text {
             print(text)
           }
         }
       } else {
-        let content = try await model.generateContent(input)
+        // Unary generate content
+        let content = try await chat.sendMessage(input)
         if let text = content.text {
           print("Generated Content:\n\(text)")
         }
@@ -123,6 +135,76 @@ struct GenerateContent: AsyncParsableCommand {
       return "gemini-1.0-pro"
     }
   }
+
+  // MARK: - Callable Functions
+
+  // Returns exchange rates from the Frankfurter API
+  // This is an example function that a developer might provide.
+  func getExchangeRate(amount: Double, date: String, from: String,
+                       to: String) async throws -> String {
+    var urlComponents = URLComponents(string: "https://api.frankfurter.app")!
+    urlComponents.path = "/\(date)"
+    urlComponents.queryItems = [
+      .init(name: "amount", value: String(amount)),
+      .init(name: "from", value: from),
+      .init(name: "to", value: to),
+    ]
+
+    let (data, _) = try await URLSession.shared.data(from: urlComponents.url!)
+    return String(data: data, encoding: .utf8)!
+  }
+
+  // This is a wrapper for the `getExchangeRate` function.
+  func getExchangeRateWrapper(args: JSONObject) async throws -> JSONObject {
+    // 1. Validate and extract the parameters provided by the model (from a `FunctionCall`)
+    guard case let .string(date) = args["currency_date"] else {
+      fatalError()
+    }
+    guard case let .string(from) = args["currency_from"] else {
+      fatalError()
+    }
+    guard case let .string(to) = args["currency_to"] else {
+      fatalError()
+    }
+    guard case let .number(amount) = args["amount"] else {
+      fatalError()
+    }
+
+    // 2. Call the wrapped function
+    let response = try await getExchangeRate(amount: amount, date: date, from: from, to: to)
+
+    // 3. Return the exchange rates as a JSON object (returned to the model in a `FunctionResponse`)
+    return ["content": .string(response)]
+  }
+
+  // Returns the schema of the `getExchangeRate` function
+  func getExchangeRateSchema() -> Schema {
+    return Schema(
+      type: .object,
+      properties: [
+        "currency_date": Schema(
+          type: .string,
+          description: """
+          A date that must always be in YYYY-MM-DD format or the value 'latest' if a time period
+          is not specified
+          """
+        ),
+        "currency_from": Schema(
+          type: .string,
+          description: "The currency to convert from in ISO 4217 format"
+        ),
+        "currency_to": Schema(
+          type: .string,
+          description: "The currency to convert to in ISO 4217 format"
+        ),
+        "amount": Schema(
+          type: .number,
+          description: "The amount of currency to convert as a double value"
+        ),
+      ],
+      required: ["currency_date", "currency_from", "currency_to", "amount"]
+    )
+  }
 }
 
 enum CLIError: Error {

Sources/GoogleAI/Chat.swift

@@ -70,10 +70,32 @@ public class Chat {
     // Make sure we inject the role into the content received.
     let toAdd = ModelContent(role: "model", parts: reply.parts)
 
+    var functionResponses = [FunctionResponse]()
+    for part in reply.parts {
+      if case let .functionCall(functionCall) = part {
+        try functionResponses.append(await model.executeFunction(functionCall: functionCall))
+      }
+    }
+
+    // Call the functions requested by the model, if any.
+    let functionResponseContent = try ModelContent(
+      role: "function",
+      functionResponses.map { functionResponse in
+        ModelContent.Part.functionResponse(functionResponse)
+      }
+    )
+
     // Append the request and successful result to history, then return the value.
     history.append(contentsOf: newContent)
     history.append(toAdd)
-    return result
+
+    // If no function calls requested, return the results.
+    if functionResponses.isEmpty {
+      return result
+    }
+
+    // Re-send the message with the function responses.
+    return try await sendMessage([functionResponseContent])
   }
 
   /// See ``sendMessageStream(_:)-4abs3``.
@@ -162,6 +184,14 @@ public class Chat {
           }
 
           parts.append(part)
+
+        case .functionCall:
+          // TODO(andrewheard): Add function call to the chat history when encoding is implemented.
+          fatalError("Function calling not yet implemented in chat.")
+
+        case .functionResponse:
+          // TODO(andrewheard): Add function response to chat history when encoding is implemented.
+          fatalError("Function calling not yet implemented in chat.")
         }
       }
     }

Sources/GoogleAI/FunctionCalling.swift

@@ -0,0 +1,139 @@
+// Copyright 2024 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import Foundation
+
+/// A predicted function call returned from the model.
+///
+/// REST Docs: https://ai.google.dev/api/rest/v1beta/Content#functioncall
+public struct FunctionCall: Equatable, Encodable {
+  /// The name of the function to call.
+  public let name: String
+
+  /// The function parameters and values.
+  public let args: JSONObject
+}
+
+// REST Docs: https://ai.google.dev/api/rest/v1beta/Tool#schema
+public class Schema: Encodable {
+  let type: DataType
+
+  let format: String?
+
+  let description: String?
+
+  let nullable: Bool?
+
+  let enumValues: [String]?
+
+  let items: Schema?
+
+  let properties: [String: Schema]?
+
+  let required: [String]?
+
+  public init(type: DataType, format: String? = nil, description: String? = nil,
+              nullable: Bool? = nil,
+              enumValues: [String]? = nil, items: Schema? = nil,
+              properties: [String: Schema]? = nil,
+              required: [String]? = nil) {
+    self.type = type
+    self.format = format
+    self.description = description
+    self.nullable = nullable
+    self.enumValues = enumValues
+    self.items = items
+    self.properties = properties
+    self.required = required
+  }
+}
+
+// REST Docs: https://ai.google.dev/api/rest/v1beta/Tool#Type
+public enum DataType: String, Encodable {
+  case string = "STRING"
+  case number = "NUMBER"
+  case integer = "INTEGER"
+  case boolean = "BOOLEAN"
+  case array = "ARRAY"
+  case object = "OBJECT"
+}
+
+// REST Docs: https://ai.google.dev/api/rest/v1beta/Tool#FunctionDeclaration
+public struct FunctionDeclaration {
+  let name: String
+
+  let description: String
+
+  let parameters: Schema
+
+  let function: ((JSONObject) async throws -> JSONObject)?
+
+  public init(name: String, description: String, parameters: Schema,
+              function: ((JSONObject) async throws -> JSONObject)?) {
+    self.name = name
+    self.description = description
+    self.parameters = parameters
+    self.function = function
+  }
+}
+
+// REST Docs: https://ai.google.dev/api/rest/v1beta/Tool
+public struct Tool: Encodable {
+  let functionDeclarations: [FunctionDeclaration]?
+
+  public init(functionDeclarations: [FunctionDeclaration]?) {
+    self.functionDeclarations = functionDeclarations
+  }
+}
+
+// REST Docs: https://ai.google.dev/api/rest/v1beta/Content#functionresponse
+public struct FunctionResponse: Equatable, Encodable {
+  let name: String
+
+  let response: JSONObject
+}
+
+// MARK: - Codable Conformance
+
+extension FunctionCall: Decodable {
+  enum CodingKeys: CodingKey {
+    case name
+    case args
+  }
+
+  public init(from decoder: Decoder) throws {
+    let container = try decoder.container(keyedBy: CodingKeys.self)
+    name = try container.decode(String.self, forKey: .name)
+    if let args = try container.decodeIfPresent(JSONObject.self, forKey: .args) {
+      self.args = args
+    } else {
+      args = JSONObject()
+    }
+  }
+}
+
+extension FunctionDeclaration: Encodable {
+  enum CodingKeys: String, CodingKey {
+    case name
+    case description
+    case parameters
+  }
+
+  public func encode(to encoder: Encoder) throws {
+    var container = encoder.container(keyedBy: CodingKeys.self)
+    try container.encode(name, forKey: .name)
+    try container.encode(description, forKey: .description)
+    try container.encode(parameters, forKey: .parameters)
+  }
+}

Sources/GoogleAI/GenerateContentRequest.swift

@@ -21,6 +21,7 @@ struct GenerateContentRequest {
   let contents: [ModelContent]
   let generationConfig: GenerationConfig?
   let safetySettings: [SafetySetting]?
+  let tools: [Tool]?
   let isStreaming: Bool
   let options: RequestOptions
 }
@@ -31,6 +32,7 @@ extension GenerateContentRequest: Encodable {
     case contents
     case generationConfig
     case safetySettings
+    case tools
   }
 }