[Vertex AI] Refactor FinishReason as a struct and add new values (#13860)

Author: andrewheard

FirebaseVertexAI/CHANGELOG.md

@@ -36,10 +36,10 @@
  as input. (#13767)
 -[changed]**Breaking Change**: All initializers for `ModelContent` now require
  the label `parts: `. (#13832)
--[changed]**Breaking Change**: `HarmCategory` and `HarmProbability` are now
- structs instead of enums types and the `unknown` cases have been removed; in a
-`switch` statement, use the `default:` case to cover unknown or unhandled
-categories or probabilities. (#13728, #13854)
+-[changed]**Breaking Change**: `HarmCategory`, `HarmProbability`, and
+`FinishReason` are now structs instead of enums types and the `unknown` cases
+have been removed; in a `switch` statement, use the `default:` case to cover
+unknown or unhandled values. (#13728, #13854, #13860)
 -[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/Sources/GenerateContentResponse.swift

@@ -145,26 +145,76 @@ public struct Citation: Sendable {
 
 /// A value enumerating possible reasons for a model to terminate a content generation request.
 @available(iOS 15.0, macOS 11.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0,*)
-publicenumFinishReason:String,Sendable{
- /// The finish reason is unknown.
-case unknown ="FINISH_REASON_UNKNOWN"
+publicstructFinishReason:DecodableProtoEnum,Hashable,Sendable{
+enumKind:String{
+case stop ="STOP"
+case maxTokens ="MAX_TOKENS"
+case safety ="SAFETY"
+case recitation ="RECITATION"
+case other ="OTHER"
+case blocklist ="BLOCKLIST"
+case prohibitedContent ="PROHIBITED_CONTENT"
+case spii ="SPII"
+case malformedFunctionCall ="MALFORMED_FUNCTION_CALL"
+}
 
  /// Natural stop point of the model or provided stop sequence.
-case stop ="STOP"
+publicstaticvarstop:FinishReason{
+returnself.init(kind:.stop)
+}
 
  /// The maximum number of tokens as specified in the request was reached.
-case maxTokens ="MAX_TOKENS"
+publicstaticvarmaxTokens:FinishReason{
+returnself.init(kind:.maxTokens)
+}
 
  /// The token generation was stopped because the response was flagged for safety reasons.
- /// NOTE: When streaming, the Candidate.content will be empty if content filters blocked the
- /// output.
-case safety ="SAFETY"
+ ///
+ /// > NOTE: When streaming, the ``CandidateResponse/content`` will be empty if content filters
+ /// > blocked the output.
+publicstaticvarsafety:FinishReason{
+returnself.init(kind:.safety)
+}
 
  /// The token generation was stopped because the response was flagged for unauthorized citations.
-case recitation ="RECITATION"
+publicstaticvarrecitation:FinishReason{
+returnself.init(kind:.recitation)
+}
 
  /// All other reasons that stopped token generation.
-case other ="OTHER"
+publicstaticvarother:FinishReason{
+returnself.init(kind:.other)
+}
+
+ /// Token generation was stopped because the response contained forbidden terms.
+publicstaticvarblocklist:FinishReason{
+returnself.init(kind:.blocklist)
+}
+
+ /// Token generation was stopped because the response contained potentially prohibited content.
+publicstaticvarprohibitedContent:FinishReason{
+returnself.init(kind:.prohibitedContent)
+}
+
+ /// Token generation was stopped because of Sensitive Personally Identifiable Information (SPII).
+publicstaticvarspii:FinishReason{
+returnself.init(kind:.spii)
+}
+
+ /// Token generation was stopped because the function call generated by the model was invalid.
+publicstaticvarmalformedFunctionCall:FinishReason{
+returnself.init(kind:.malformedFunctionCall)
+}
+
+ /// Returns the raw string representation of the `FinishReason` value.
+ ///
+ /// > Note: This value directly corresponds to the values in the [REST
+ /// > API](https://cloud.google.com/vertex-ai/docs/reference/rest/v1beta1/GenerateContentResponse#FinishReason).
+publicletrawValue:String
+
+varunrecognizedValueMessageCode:VertexLog.MessageCode{
+.generateContentResponseUnrecognizedFinishReason
+}
 }
 
 /// A metadata struct containing any feedback the model had on the prompt it was provided.
@@ -333,23 +383,6 @@ extension Citation: Decodable {
 }
 }
 
-@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0,*)
-extensionFinishReason:Decodable{
-publicinit(from decoder:Decoder)throws{
-letvalue=try decoder.singleValueContainer().decode(String.self)
-guardlet decodedFinishReason =FinishReason(rawValue: value)else{
-VertexLog.error(
- code:.generateContentResponseUnrecognizedFinishReason,
-"Unrecognized FinishReason with value \"\(value)\"."
-)
-self=.unknown
-return
-}
-
-self= decodedFinishReason
-}
-}
-
 @available(iOS 15.0, macOS 11.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0,*)
 extensionPromptFeedback.BlockReason:Decodable{
 publicinit(from decoder:Decoder)throws{

FirebaseVertexAI/Tests/Unit/GenerativeModelTests.swift

@@ -608,12 +608,13 @@ final class GenerativeModelTests: XCTestCase {
  forResource:"unary-failure-unknown-enum-finish-reason",
  withExtension:"json"
 )
+letunknownFinishReason=FinishReason(rawValue:"FAKE_NEW_FINISH_REASON")
 
 do{
  _ =tryawait model.generateContent(testPrompt)
 XCTFail("Should throw")
 }catchletGenerateContentError.responseStoppedEarly(reason, response){
-XCTAssertEqual(reason,.unknown)
+XCTAssertEqual(reason,unknownFinishReason)
 XCTAssertEqual(response.text,"Some text")
 }catch{
 XCTFail("Should throw a responseStoppedEarly")
@@ -921,14 +922,15 @@ final class GenerativeModelTests: XCTestCase {
  forResource:"streaming-failure-unknown-finish-enum",
  withExtension:"txt"
 )
+letunknownFinishReason=FinishReason(rawValue:"FAKE_ENUM")
 
 letstream=try model.generateContentStream("Hi")
 do{
 fortryawaitcontentin stream {
 XCTAssertNotNil(content.text)
 }
 }catchletGenerateContentError.responseStoppedEarly(reason, _){
-XCTAssertEqual(reason,.unknown)
+XCTAssertEqual(reason,unknownFinishReason)
 return
 }