[Vertex AI] Simplify ModelContent initializers (#13832)

Co-authored-by: Ryan Wilson <wilsonryan@google.com>

FirebaseVertexAI/CHANGELOG.md

@@ -34,6 +34,8 @@
   generating content the types `TextPart`; additionally the types
   `InlineDataPart`, `FileDataPart` and `FunctionResponsePart` may be provided
   as input. (#13767)
+- [changed] **Breaking Change**: All initializers for `ModelContent` now require
+  the label `parts: `. (#13832)
 - [changed] The default request timeout is now 180 seconds instead of the
   platform-default value of 60 seconds for a `URLRequest`; this timeout may
   still be customized in `RequestOptions`. (#13722)

FirebaseVertexAI/Sample/ChatSample/Views/ErrorDetailsView.swift

@@ -160,12 +160,11 @@ struct ErrorDetailsView: View {
   let error = GenerateContentError.responseStoppedEarly(
     reason: .maxTokens,
     response: GenerateContentResponse(candidates: [
-      CandidateResponse(content: ModelContent(role: "model", [
+      CandidateResponse(content: ModelContent(role: "model", parts:
         """
         A _hypothetical_ model response.
         Cillum ex aliqua amet aliquip labore amet eiusmod consectetur reprehenderit sit commodo.
-        """,
-      ]),
+        """),
       safetyRatings: [
         SafetyRating(category: .dangerousContent, probability: .high),
         SafetyRating(category: .harassment, probability: .low),
@@ -183,12 +182,11 @@ struct ErrorDetailsView: View {
 #Preview("Prompt Blocked") {
   let error = GenerateContentError.promptBlocked(
     response: GenerateContentResponse(candidates: [
-      CandidateResponse(content: ModelContent(role: "model", [
+      CandidateResponse(content: ModelContent(role: "model", parts:
         """
         A _hypothetical_ model response.
         Cillum ex aliqua amet aliquip labore amet eiusmod consectetur reprehenderit sit commodo.
-        """,
-      ]),
+        """),
       safetyRatings: [
         SafetyRating(category: .dangerousContent, probability: .high),
         SafetyRating(category: .harassment, probability: .low),

FirebaseVertexAI/Sample/ChatSample/Views/ErrorView.swift

@@ -37,7 +37,7 @@ struct ErrorView: View {
   NavigationView {
     let errorPromptBlocked = GenerateContentError.promptBlocked(
       response: GenerateContentResponse(candidates: [
-        CandidateResponse(content: ModelContent(role: "model", [
+        CandidateResponse(content: ModelContent(role: "model", parts: [
           """
             A _hypothetical_ model response.
             Cillum ex aliqua amet aliquip labore amet eiusmod consectetur reprehenderit sit commodo.

FirebaseVertexAI/Sources/ModelContent.swift

@@ -71,32 +71,6 @@ public struct ModelContent: Equatable, Sendable {
   // TODO: Refactor this
   let internalParts: [InternalPart]
 
-  /// Creates a new value from any data or `Array` of data interpretable as a
-  /// ``Part``. See ``PartsRepresentable`` for types that can be interpreted as `Part`s.
-  public init(role: String? = "user", parts: some PartsRepresentable) {
-    self.role = role
-    var convertedParts = [InternalPart]()
-    for part in parts.partsValue {
-      switch part {
-      case let textPart as TextPart:
-        convertedParts.append(.text(textPart.text))
-      case let inlineDataPart as InlineDataPart:
-        let inlineData = inlineDataPart.inlineData
-        convertedParts.append(.inlineData(mimetype: inlineData.mimeType, inlineData.data))
-      case let fileDataPart as FileDataPart:
-        let fileData = fileDataPart.fileData
-        convertedParts.append(.fileData(mimetype: fileData.mimeType, uri: fileData.fileURI))
-      case let functionCallPart as FunctionCallPart:
-        convertedParts.append(.functionCall(functionCallPart.functionCall))
-      case let functionResponsePart as FunctionResponsePart:
-        convertedParts.append(.functionResponse(functionResponsePart.functionResponse))
-      default:
-        fatalError()
-      }
-    }
-    internalParts = convertedParts
-  }
-
   /// Creates a new value from a list of ``Part``s.
   public init(role: String? = "user", parts: [any Part]) {
     self.role = role
@@ -124,14 +98,7 @@ public struct ModelContent: Equatable, Sendable {
 
   /// Creates a new value from any data interpretable as a ``Part``.
   /// See ``PartsRepresentable`` for types that can be interpreted as `Part`s.
-  public init(role: String? = "user", _ parts: any PartsRepresentable...) {
-    let content = parts.flatMap { $0.partsValue }
-    self.init(role: role, parts: content)
-  }
-
-  /// Creates a new value from any data interpretable as a ``Part``.
-  /// See ``PartsRepresentable``for types that can be interpreted as `Part`s.
-  public init(role: String? = "user", _ parts: [PartsRepresentable]) {
+  public init(role: String? = "user", parts: any PartsRepresentable...) {
     let content = parts.flatMap { $0.partsValue }
     self.init(role: role, parts: content)
   }

FirebaseVertexAI/Tests/Unit/VertexAIAPITests.swift

@@ -106,8 +106,8 @@ final class VertexAIAPITests: XCTestCase {
       _ = try await genAI.generateContent([str, UIImage(), TextPart(str)])
       _ = try await genAI.generateContent(str, UIImage(), "def", UIImage())
       _ = try await genAI.generateContent([str, UIImage(), "def", UIImage()])
-      _ = try await genAI.generateContent([ModelContent("def", UIImage()),
-                                           ModelContent("def", UIImage())])
+      _ = try await genAI.generateContent([ModelContent(parts: "def", UIImage()),
+                                           ModelContent(parts: "def", UIImage())])
     #elseif canImport(AppKit)
       _ = try await genAI.generateContent(NSImage())
       _ = try await genAI.generateContent([NSImage()])
@@ -121,37 +121,25 @@ final class VertexAIAPITests: XCTestCase {
     let _ = ModelContent(parts: "Constant String")
     let _ = ModelContent(parts: str)
     let _ = ModelContent(parts: [str])
-    // Note: without `as [any PartsRepresentable]` this will fail to compile with "Cannot
-    // convert value of type 'String' to expected element type
-    // 'Array<Part>.ArrayLiteralElement'. Not sure if there's a way we can get it to
-    // work.
-    let _ = ModelContent(
-      parts: [str, InlineDataPart(data: Data(), mimeType: "foo")] as [any PartsRepresentable]
-    )
+    let _ = ModelContent(parts: [str, InlineDataPart(data: Data(), mimeType: "foo")])
     #if canImport(UIKit)
       _ = ModelContent(role: "user", parts: UIImage())
       _ = ModelContent(role: "user", parts: [UIImage()])
-      // Note: without `as [any PartsRepresentable]` this will fail to compile with "Cannot convert
-      // value of type `[Any]` to expected type `[any PartsRepresentable]`. Not sure if there's a
-      // way we can get it to work.
-      _ = ModelContent(parts: [str, UIImage()] as [any PartsRepresentable])
-      // Alternatively, you can explicitly declare the type in a variable and pass it in.
+      _ = ModelContent(parts: [str, UIImage()])
+      // Note: without explicitly specifying`: [any PartsRepresentable]` this will fail to compile
+      // below with "Cannot convert value of type `[Any]` to expected type `[any Part]`.
       let representable2: [any PartsRepresentable] = [str, UIImage()]
       _ = ModelContent(parts: representable2)
-      _ =
-        ModelContent(parts: [str, UIImage(), TextPart(str)] as [any PartsRepresentable])
+      _ = ModelContent(parts: [str, UIImage(), TextPart(str)])
     #elseif canImport(AppKit)
       _ = ModelContent(role: "user", parts: NSImage())
       _ = ModelContent(role: "user", parts: [NSImage()])
-      // Note: without `as [any PartsRepresentable]` this will fail to compile with "Cannot convert
-      // value of type `[Any]` to expected type `[any PartsRepresentable]`. Not sure if there's a
-      // way we can get it to work.
-      _ = ModelContent(parts: [str, NSImage()] as [any PartsRepresentable])
-      // Alternatively, you can explicitly declare the type in a variable and pass it in.
+      _ = ModelContent(parts: [str, NSImage()])
+      // Note: without explicitly specifying`: [any PartsRepresentable]` this will fail to compile
+      // below with "Cannot convert value of type `[Any]` to expected type `[any Part]`.
       let representable2: [any PartsRepresentable] = [str, NSImage()]
       _ = ModelContent(parts: representable2)
-      _ =
-        ModelContent(parts: [str, NSImage(), TextPart(str)] as [any PartsRepresentable])
+      _ = ModelContent(parts: [str, NSImage(), TextPart(str)])
     #endif
 
     // countTokens API
@@ -160,8 +148,8 @@ final class VertexAIAPITests: XCTestCase {
       let _: CountTokensResponse = try await genAI.countTokens("What color is the Sky?",
                                                                UIImage())
       let _: CountTokensResponse = try await genAI.countTokens([
-        ModelContent("What color is the Sky?", UIImage()),
-        ModelContent(UIImage(), "What color is the Sky?", UIImage()),
+        ModelContent(parts: "What color is the Sky?", UIImage()),
+        ModelContent(parts: UIImage(), "What color is the Sky?", UIImage()),
       ])
     #endif