From 584b1e9a8561716a34b16b8729ca9b85a60f0f95 Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Fri, 19 Apr 2024 17:04:35 -0400
Subject: [PATCH] Remove public `Codable` (`Decodable` and/or `Encodable`)
 conformance (#142)

---
 Sources/GoogleAI/CountTokensRequest.swift     |  21 +-
 Sources/GoogleAI/FunctionCalling.swift        |  33 ++-
 .../GoogleAI/GenerateContentResponse.swift    | 241 +++++++++---------
 Sources/GoogleAI/GenerationConfig.swift       |   7 +-
 Sources/GoogleAI/ModelContent.swift           | 146 ++++++-----
 Sources/GoogleAI/Safety.swift                 | 108 ++++----
 6 files changed, 302 insertions(+), 254 deletions(-)

diff --git a/Sources/GoogleAI/CountTokensRequest.swift b/Sources/GoogleAI/CountTokensRequest.swift
index 0a58d40..de852ae 100644
--- a/Sources/GoogleAI/CountTokensRequest.swift
+++ b/Sources/GoogleAI/CountTokensRequest.swift
@@ -21,13 +21,6 @@ struct CountTokensRequest {
   let options: RequestOptions
 }
 
-@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
-extension CountTokensRequest: Encodable {
-  enum CodingKeys: CodingKey {
-    case contents
-  }
-}
-
 @available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
 extension CountTokensRequest: GenerativeAIRequest {
   typealias Response = CountTokensResponse
@@ -39,7 +32,19 @@ extension CountTokensRequest: GenerativeAIRequest {
 
 /// The model's response to a count tokens request.
 @available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
-public struct CountTokensResponse: Decodable {
+public struct CountTokensResponse {
   /// The total number of tokens in the input given to the model as a prompt.
   public let totalTokens: Int
 }
+
+// MARK: - Codable Conformances
+
+@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
+extension CountTokensRequest: Encodable {
+  enum CodingKeys: CodingKey {
+    case contents
+  }
+}
+
+@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
+extension CountTokensResponse: Decodable {}
diff --git a/Sources/GoogleAI/FunctionCalling.swift b/Sources/GoogleAI/FunctionCalling.swift
index 8860344..17c9611 100644
--- a/Sources/GoogleAI/FunctionCalling.swift
+++ b/Sources/GoogleAI/FunctionCalling.swift
@@ -15,7 +15,7 @@
 import Foundation
 
 /// A predicted function call returned from the model.
-public struct FunctionCall: Equatable, Encodable {
+public struct FunctionCall: Equatable {
   /// The name of the function to call.
   public let name: String
 
@@ -27,7 +27,7 @@ public struct FunctionCall: Equatable, Encodable {
 ///
 /// These types can be objects, but also primitives and arrays. Represents a select subset of an
 /// [OpenAPI 3.0 schema object](https://spec.openapis.org/oas/v3.0.3#schema).
-public class Schema: Encodable {
+public class Schema {
   /// The data type.
   let type: DataType
 
@@ -98,7 +98,7 @@ public class Schema: Encodable {
 /// A data type.
 ///
 /// Contains the set of OpenAPI [data types](https://spec.openapis.org/oas/v3.0.3#data-types).
-public enum DataType: String, Encodable {
+public enum DataType: String {
   /// A `String` type.
   case string = "STRING"
 
@@ -157,7 +157,7 @@ public struct FunctionDeclaration {
 ///
 /// A `Tool` is a piece of code that enables the system to interact with external systems to
 /// perform an action, or set of actions, outside of knowledge and scope of the model.
-public struct Tool: Encodable {
+public struct Tool {
   /// A list of `FunctionDeclarations` available to the model.
   let functionDeclarations: [FunctionDeclaration]?
 
@@ -178,10 +178,10 @@ public struct Tool: Encodable {
 }
 
 /// Configuration for specifying function calling behavior.
-public struct FunctionCallingConfig: Encodable {
+public struct FunctionCallingConfig {
   /// Defines the execution behavior for function calling by defining the
   /// execution mode.
-  public enum Mode: String, Encodable {
+  public enum Mode: String {
     /// The default behavior for function calling. The model calls functions to answer queries at
     /// its discretion.
     case auto = "AUTO"
@@ -213,8 +213,7 @@ public struct FunctionCallingConfig: Encodable {
 }
 
 /// Tool configuration for any `Tool` specified in the request.
-@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
-public struct ToolConfig: Encodable {
+public struct ToolConfig {
   let functionCallingConfig: FunctionCallingConfig?
 
   public init(functionCallingConfig: FunctionCallingConfig? = nil) {
@@ -227,7 +226,7 @@ public struct ToolConfig: Encodable {
 /// Contains a string representing the `FunctionDeclaration.name` and a structured JSON object
 /// containing any output from the function is used as context to the model. This should contain the
 /// result of a ``FunctionCall`` made based on model prediction.
-public struct FunctionResponse: Equatable, Encodable {
+public struct FunctionResponse: Equatable {
   /// The name of the function that was called.
   let name: String
 
@@ -264,6 +263,8 @@ extension FunctionCall: Decodable {
   }
 }
 
+extension FunctionCall: Encodable {}
+
 extension FunctionDeclaration: Encodable {
   enum CodingKeys: String, CodingKey {
     case name
@@ -278,3 +279,17 @@ extension FunctionDeclaration: Encodable {
     try container.encode(parameters, forKey: .parameters)
   }
 }
+
+extension Schema: Encodable {}
+
+extension DataType: Encodable {}
+
+extension Tool: Encodable {}
+
+extension FunctionCallingConfig: Encodable {}
+
+extension FunctionCallingConfig.Mode: Encodable {}
+
+extension ToolConfig: Encodable {}
+
+extension FunctionResponse: Encodable {}
diff --git a/Sources/GoogleAI/GenerateContentResponse.swift b/Sources/GoogleAI/GenerateContentResponse.swift
index e623d74..4b01522 100644
--- a/Sources/GoogleAI/GenerateContentResponse.swift
+++ b/Sources/GoogleAI/GenerateContentResponse.swift
@@ -57,38 +57,6 @@ public struct GenerateContentResponse {
   }
 }
 
-@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
-extension GenerateContentResponse: Decodable {
-  enum CodingKeys: CodingKey {
-    case candidates
-    case promptFeedback
-  }
-
-  public init(from decoder: Decoder) throws {
-    let container = try decoder.container(keyedBy: CodingKeys.self)
-
-    guard container.contains(CodingKeys.candidates) || container
-      .contains(CodingKeys.promptFeedback) else {
-      let context = DecodingError.Context(
-        codingPath: [],
-        debugDescription: "Failed to decode GenerateContentResponse;" +
-          " missing keys 'candidates' and 'promptFeedback'."
-      )
-      throw DecodingError.dataCorrupted(context)
-    }
-
-    if let candidates = try container.decodeIfPresent(
-      [CandidateResponse].self,
-      forKey: .candidates
-    ) {
-      self.candidates = candidates
-    } else {
-      candidates = []
-    }
-    promptFeedback = try container.decodeIfPresent(PromptFeedback.self, forKey: .promptFeedback)
-  }
-}
-
 /// A struct representing a possible reply to a content generation prompt. Each content generation
 /// prompt may produce multiple candidate responses.
 @available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
@@ -116,58 +84,9 @@ public struct CandidateResponse {
   }
 }
 
-@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
-extension CandidateResponse: Decodable {
-  enum CodingKeys: CodingKey {
-    case content
-    case safetyRatings
-    case finishReason
-    case finishMessage
-    case citationMetadata
-  }
-
-  /// Initializes a response from a decoder. Used for decoding server responses; not for public
-  /// use.
-  public init(from decoder: Decoder) throws {
-    let container = try decoder.container(keyedBy: CodingKeys.self)
-
-    do {
-      if let content = try container.decodeIfPresent(ModelContent.self, forKey: .content) {
-        self.content = content
-      } else {
-        content = ModelContent(parts: [])
-      }
-    } catch {
-      // Check if `content` can be decoded as an empty dictionary to detect the `"content": {}` bug.
-      if let content = try? container.decode([String: String].self, forKey: .content),
-         content.isEmpty {
-        throw InvalidCandidateError.emptyContent(underlyingError: error)
-      } else {
-        throw InvalidCandidateError.malformedContent(underlyingError: error)
-      }
-    }
-
-    if let safetyRatings = try container.decodeIfPresent(
-      [SafetyRating].self,
-      forKey: .safetyRatings
-    ) {
-      self.safetyRatings = safetyRatings
-    } else {
-      safetyRatings = []
-    }
-
-    finishReason = try container.decodeIfPresent(FinishReason.self, forKey: .finishReason)
-
-    citationMetadata = try container.decodeIfPresent(
-      CitationMetadata.self,
-      forKey: .citationMetadata
-    )
-  }
-}
-
 /// A collection of source attributions for a piece of content.
 @available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
-public struct CitationMetadata: Decodable {
+public struct CitationMetadata {
   /// A list of individual cited sources and the parts of the content to which they apply.
   public let citationSources: [Citation]
 }
@@ -213,27 +132,11 @@ public enum FinishReason: String {
   case other = "OTHER"
 }
 
-@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
-extension FinishReason: Decodable {
-  /// Do not explicitly use. Initializer required for Decodable conformance.
-  public init(from decoder: Decoder) throws {
-    let value = try decoder.singleValueContainer().decode(String.self)
-    guard let decodedFinishReason = FinishReason(rawValue: value) else {
-      Logging.default
-        .error("[GoogleGenerativeAI] Unrecognized FinishReason with value \"\(value)\".")
-      self = .unknown
-      return
-    }
-
-    self = decodedFinishReason
-  }
-}
-
 /// A metadata struct containing any feedback the model had on the prompt it was provided.
 @available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
 public struct PromptFeedback {
   /// A type describing possible reasons to block a prompt.
-  public enum BlockReason: String, Decodable {
+  public enum BlockReason: String {
     /// The block reason is unknown.
     case unknown = "UNKNOWN"
 
@@ -245,19 +148,6 @@ public struct PromptFeedback {
 
     /// All other block reasons.
     case other = "OTHER"
-
-    /// Do not explicitly use. Initializer required for Decodable conformance.
-    public init(from decoder: Decoder) throws {
-      let value = try decoder.singleValueContainer().decode(String.self)
-      guard let decodedBlockReason = BlockReason(rawValue: value) else {
-        Logging.default
-          .error("[GoogleGenerativeAI] Unrecognized BlockReason with value \"\(value)\".")
-        self = .unknown
-        return
-      }
-
-      self = decodedBlockReason
-    }
   }
 
   /// The reason a prompt was blocked, if it was blocked.
@@ -273,20 +163,69 @@ public struct PromptFeedback {
   }
 }
 
+// MARK: - Codable Conformances
+
 @available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
-extension PromptFeedback: Decodable {
+extension GenerateContentResponse: Decodable {
   enum CodingKeys: CodingKey {
-    case blockReason
+    case candidates
+    case promptFeedback
+  }
+
+  public init(from decoder: Decoder) throws {
+    let container = try decoder.container(keyedBy: CodingKeys.self)
+
+    guard container.contains(CodingKeys.candidates) || container
+      .contains(CodingKeys.promptFeedback) else {
+      let context = DecodingError.Context(
+        codingPath: [],
+        debugDescription: "Failed to decode GenerateContentResponse;" +
+          " missing keys 'candidates' and 'promptFeedback'."
+      )
+      throw DecodingError.dataCorrupted(context)
+    }
+
+    if let candidates = try container.decodeIfPresent(
+      [CandidateResponse].self,
+      forKey: .candidates
+    ) {
+      self.candidates = candidates
+    } else {
+      candidates = []
+    }
+    promptFeedback = try container.decodeIfPresent(PromptFeedback.self, forKey: .promptFeedback)
+  }
+}
+
+@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
+extension CandidateResponse: Decodable {
+  enum CodingKeys: CodingKey {
+    case content
     case safetyRatings
+    case finishReason
+    case finishMessage
+    case citationMetadata
   }
 
-  /// Do not explicitly use. Initializer required for Decodable conformance.
   public init(from decoder: Decoder) throws {
     let container = try decoder.container(keyedBy: CodingKeys.self)
-    blockReason = try container.decodeIfPresent(
-      PromptFeedback.BlockReason.self,
-      forKey: .blockReason
-    )
+
+    do {
+      if let content = try container.decodeIfPresent(ModelContent.self, forKey: .content) {
+        self.content = content
+      } else {
+        content = ModelContent(parts: [])
+      }
+    } catch {
+      // Check if `content` can be decoded as an empty dictionary to detect the `"content": {}` bug.
+      if let content = try? container.decode([String: String].self, forKey: .content),
+         content.isEmpty {
+        throw InvalidCandidateError.emptyContent(underlyingError: error)
+      } else {
+        throw InvalidCandidateError.malformedContent(underlyingError: error)
+      }
+    }
+
     if let safetyRatings = try container.decodeIfPresent(
       [SafetyRating].self,
       forKey: .safetyRatings
@@ -295,10 +234,18 @@ extension PromptFeedback: Decodable {
     } else {
       safetyRatings = []
     }
+
+    finishReason = try container.decodeIfPresent(FinishReason.self, forKey: .finishReason)
+
+    citationMetadata = try container.decodeIfPresent(
+      CitationMetadata.self,
+      forKey: .citationMetadata
+    )
   }
 }
 
-// MARK: - Codable Conformances
+@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
+extension CitationMetadata: Decodable {}
 
 @available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
 extension Citation: Decodable {
@@ -322,3 +269,57 @@ extension Citation: Decodable {
     }
   }
 }
+
+@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
+extension FinishReason: Decodable {
+  public init(from decoder: Decoder) throws {
+    let value = try decoder.singleValueContainer().decode(String.self)
+    guard let decodedFinishReason = FinishReason(rawValue: value) else {
+      Logging.default
+        .error("[GoogleGenerativeAI] Unrecognized FinishReason with value \"\(value)\".")
+      self = .unknown
+      return
+    }
+
+    self = decodedFinishReason
+  }
+}
+
+@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
+extension PromptFeedback.BlockReason: Decodable {
+  public init(from decoder: Decoder) throws {
+    let value = try decoder.singleValueContainer().decode(String.self)
+    guard let decodedBlockReason = PromptFeedback.BlockReason(rawValue: value) else {
+      Logging.default
+        .error("[GoogleGenerativeAI] Unrecognized BlockReason with value \"\(value)\".")
+      self = .unknown
+      return
+    }
+
+    self = decodedBlockReason
+  }
+}
+
+@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
+extension PromptFeedback: Decodable {
+  enum CodingKeys: CodingKey {
+    case blockReason
+    case safetyRatings
+  }
+
+  public init(from decoder: Decoder) throws {
+    let container = try decoder.container(keyedBy: CodingKeys.self)
+    blockReason = try container.decodeIfPresent(
+      PromptFeedback.BlockReason.self,
+      forKey: .blockReason
+    )
+    if let safetyRatings = try container.decodeIfPresent(
+      [SafetyRating].self,
+      forKey: .safetyRatings
+    ) {
+      self.safetyRatings = safetyRatings
+    } else {
+      safetyRatings = []
+    }
+  }
+}
diff --git a/Sources/GoogleAI/GenerationConfig.swift b/Sources/GoogleAI/GenerationConfig.swift
index 2d1016c..18bf2bd 100644
--- a/Sources/GoogleAI/GenerationConfig.swift
+++ b/Sources/GoogleAI/GenerationConfig.swift
@@ -17,7 +17,7 @@ import Foundation
 /// A struct defining model parameters to be used when sending generative AI
 /// requests to the backend model.
 @available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
-public struct GenerationConfig: Encodable {
+public struct GenerationConfig {
   /// A parameter controlling the degree of randomness in token selection. A
   /// temperature of zero is deterministic, always choosing the
   /// highest-probability response. Typical values are between 0 and 1
@@ -84,3 +84,8 @@ public struct GenerationConfig: Encodable {
     self.stopSequences = stopSequences
   }
 }
+
+// MARK: - Codable Conformances
+
+@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
+extension GenerationConfig: Encodable {}
diff --git a/Sources/GoogleAI/ModelContent.swift b/Sources/GoogleAI/ModelContent.swift
index 9c96625..70b08a6 100644
--- a/Sources/GoogleAI/ModelContent.swift
+++ b/Sources/GoogleAI/ModelContent.swift
@@ -18,28 +18,10 @@ import Foundation
 /// request or response contains an `Array` of ``ModelContent``s, and each ``ModelContent`` value
 /// may comprise multiple heterogeneous ``ModelContent/Part``s.
 @available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
-public struct ModelContent: Codable, Equatable {
+public struct ModelContent: Equatable {
   /// A discrete piece of data in a media format intepretable by an AI model. Within a single value
   /// of ``Part``, different data types may not mix.
-  public enum Part: Codable, Equatable {
-    enum CodingKeys: String, CodingKey {
-      case text
-      case inlineData
-      case fileData
-      case functionCall
-      case functionResponse
-    }
-
-    enum InlineDataKeys: String, CodingKey {
-      case mimeType = "mime_type"
-      case bytes = "data"
-    }
-
-    enum FileDataKeys: String, CodingKey {
-      case mimeType = "mime_type"
-      case url = "file_uri"
-    }
-
+  public enum Part: Equatable {
     /// Text value.
     case text(String)
 
@@ -77,56 +59,6 @@ public struct ModelContent: Codable, Equatable {
       return .data(mimetype: "image/png", data)
     }
 
-    // MARK: Codable Conformance
-
-    public func encode(to encoder: Encoder) throws {
-      var container = encoder.container(keyedBy: ModelContent.Part.CodingKeys.self)
-      switch self {
-      case let .text(a0):
-        try container.encode(a0, forKey: .text)
-      case let .data(mimetype, bytes):
-        var inlineDataContainer = container.nestedContainer(
-          keyedBy: InlineDataKeys.self,
-          forKey: .inlineData
-        )
-        try inlineDataContainer.encode(mimetype, forKey: .mimeType)
-        try inlineDataContainer.encode(bytes, forKey: .bytes)
-      case let .fileData(mimetype: mimetype, url):
-        var fileDataContainer = container.nestedContainer(
-          keyedBy: FileDataKeys.self,
-          forKey: .fileData
-        )
-        try fileDataContainer.encode(mimetype, forKey: .mimeType)
-        try fileDataContainer.encode(url, forKey: .url)
-      case let .functionCall(functionCall):
-        try container.encode(functionCall, forKey: .functionCall)
-      case let .functionResponse(functionResponse):
-        try container.encode(functionResponse, forKey: .functionResponse)
-      }
-    }
-
-    public init(from decoder: Decoder) throws {
-      let values = try decoder.container(keyedBy: CodingKeys.self)
-      if values.contains(.text) {
-        self = try .text(values.decode(String.self, forKey: .text))
-      } else if values.contains(.inlineData) {
-        let dataContainer = try values.nestedContainer(
-          keyedBy: InlineDataKeys.self,
-          forKey: .inlineData
-        )
-        let mimetype = try dataContainer.decode(String.self, forKey: .mimeType)
-        let bytes = try dataContainer.decode(Data.self, forKey: .bytes)
-        self = .data(mimetype: mimetype, bytes)
-      } else if values.contains(.functionCall) {
-        self = try .functionCall(values.decode(FunctionCall.self, forKey: .functionCall))
-      } else {
-        throw DecodingError.dataCorrupted(.init(
-          codingPath: [CodingKeys.text, CodingKeys.inlineData],
-          debugDescription: "No text, inline data or function call was found."
-        ))
-      }
-    }
-
     /// Returns the text contents of this ``Part``, if it contains text.
     public var text: String? {
       switch self {
@@ -179,3 +111,77 @@ public struct ModelContent: Codable, Equatable {
     self.init(role: role, parts: content)
   }
 }
+
+// MARK: Codable Conformances
+
+@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
+extension ModelContent: Codable {}
+
+@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
+extension ModelContent.Part: Codable {
+  enum CodingKeys: String, CodingKey {
+    case text
+    case inlineData
+    case fileData
+    case functionCall
+    case functionResponse
+  }
+
+  enum InlineDataKeys: String, CodingKey {
+    case mimeType = "mime_type"
+    case bytes = "data"
+  }
+
+  enum FileDataKeys: String, CodingKey {
+    case mimeType = "mime_type"
+    case url = "file_uri"
+  }
+
+  public func encode(to encoder: Encoder) throws {
+    var container = encoder.container(keyedBy: CodingKeys.self)
+    switch self {
+    case let .text(a0):
+      try container.encode(a0, forKey: .text)
+    case let .data(mimetype, bytes):
+      var inlineDataContainer = container.nestedContainer(
+        keyedBy: InlineDataKeys.self,
+        forKey: .inlineData
+      )
+      try inlineDataContainer.encode(mimetype, forKey: .mimeType)
+      try inlineDataContainer.encode(bytes, forKey: .bytes)
+    case let .fileData(mimetype: mimetype, url):
+      var fileDataContainer = container.nestedContainer(
+        keyedBy: FileDataKeys.self,
+        forKey: .fileData
+      )
+      try fileDataContainer.encode(mimetype, forKey: .mimeType)
+      try fileDataContainer.encode(url, forKey: .url)
+    case let .functionCall(functionCall):
+      try container.encode(functionCall, forKey: .functionCall)
+    case let .functionResponse(functionResponse):
+      try container.encode(functionResponse, forKey: .functionResponse)
+    }
+  }
+
+  public init(from decoder: Decoder) throws {
+    let values = try decoder.container(keyedBy: CodingKeys.self)
+    if values.contains(.text) {
+      self = try .text(values.decode(String.self, forKey: .text))
+    } else if values.contains(.inlineData) {
+      let dataContainer = try values.nestedContainer(
+        keyedBy: InlineDataKeys.self,
+        forKey: .inlineData
+      )
+      let mimetype = try dataContainer.decode(String.self, forKey: .mimeType)
+      let bytes = try dataContainer.decode(Data.self, forKey: .bytes)
+      self = .data(mimetype: mimetype, bytes)
+    } else if values.contains(.functionCall) {
+      self = try .functionCall(values.decode(FunctionCall.self, forKey: .functionCall))
+    } else {
+      throw DecodingError.dataCorrupted(.init(
+        codingPath: [CodingKeys.text, CodingKeys.inlineData],
+        debugDescription: "No text, inline data or function call was found."
+      ))
+    }
+  }
+}
diff --git a/Sources/GoogleAI/Safety.swift b/Sources/GoogleAI/Safety.swift
index d59511f..d2adc4a 100644
--- a/Sources/GoogleAI/Safety.swift
+++ b/Sources/GoogleAI/Safety.swift
@@ -18,7 +18,7 @@ import Foundation
 /// of this type may be assigned to a category for every model-generated response, not just
 /// responses that exceed a certain threshold.
 @available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
-public struct SafetyRating: Decodable, Equatable, Hashable {
+public struct SafetyRating: Equatable, Hashable {
   /// The category describing the potential harm a piece of content may pose. See
   /// ``SafetySetting/HarmCategory`` for a list of possible values.
   public let category: SafetySetting.HarmCategory
@@ -38,7 +38,7 @@ public struct SafetyRating: Decodable, Equatable, Hashable {
 
   /// The probability that a given model output falls under a harmful content category. This does
   /// not indicate the severity of harm for a piece of content.
-  public enum HarmProbability: String, Codable {
+  public enum HarmProbability: String {
     /// Unknown. A new server value that isn't recognized by the SDK.
     case unknown = "UNKNOWN"
 
@@ -57,26 +57,12 @@ public struct SafetyRating: Decodable, Equatable, Hashable {
 
     /// The probability is high. The content described is very likely harmful.
     case high = "HIGH"
-
-    /// Initializes a new `SafetyRating` from a decoder.
-    /// Not for external use. Initializer required for Decodable conformance.
-    public init(from decoder: Decoder) throws {
-      let value = try decoder.singleValueContainer().decode(String.self)
-      guard let decodedProbability = HarmProbability(rawValue: value) else {
-        Logging.default
-          .error("[GoogleGenerativeAI] Unrecognized HarmProbability with value \"\(value)\".")
-        self = .unknown
-        return
-      }
-
-      self = decodedProbability
-    }
   }
 }
 
 /// Safety feedback for an entire request.
 @available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
-public struct SafetyFeedback: Decodable {
+public struct SafetyFeedback {
   /// Safety rating evaluated from content.
   public let rating: SafetyRating
 
@@ -93,10 +79,10 @@ public struct SafetyFeedback: Decodable {
 /// A type used to specify a threshold for harmful content, beyond which the model will return a
 /// fallback response instead of generated content.
 @available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
-public struct SafetySetting: Codable {
+public struct SafetySetting {
   /// A type describing safety attributes, which include harmful categories and topics that can
   /// be considered sensitive.
-  public enum HarmCategory: String, Codable {
+  public enum HarmCategory: String {
     /// Unknown. A new server value that isn't recognized by the SDK.
     case unknown = "HARM_CATEGORY_UNKNOWN"
 
@@ -114,23 +100,10 @@ public struct SafetySetting: Codable {
 
     /// Promotes or enables access to harmful goods, services, or activities.
     case dangerousContent = "HARM_CATEGORY_DANGEROUS_CONTENT"
-
-    /// Do not explicitly use. Initializer required for Decodable conformance.
-    public init(from decoder: Decoder) throws {
-      let value = try decoder.singleValueContainer().decode(String.self)
-      guard let decodedCategory = HarmCategory(rawValue: value) else {
-        Logging.default
-          .error("[GoogleGenerativeAI] Unrecognized HarmCategory with value \"\(value)\".")
-        self = .unknown
-        return
-      }
-
-      self = decodedCategory
-    }
   }
 
   /// Block at and beyond a specified ``SafetyRating/HarmProbability``.
-  public enum BlockThreshold: String, Codable {
+  public enum BlockThreshold: String {
     /// Unknown. A new server value that isn't recognized by the SDK.
     case unknown = "UNKNOWN"
 
@@ -148,19 +121,6 @@ public struct SafetySetting: Codable {
 
     /// All content will be allowed.
     case blockNone = "BLOCK_NONE"
-
-    /// Do not explicitly use. Initializer required for Decodable conformance.
-    public init(from decoder: Decoder) throws {
-      let value = try decoder.singleValueContainer().decode(String.self)
-      guard let decodedThreshold = BlockThreshold(rawValue: value) else {
-        Logging.default
-          .error("[GoogleGenerativeAI] Unrecognized BlockThreshold with value \"\(value)\".")
-        self = .unknown
-        return
-      }
-
-      self = decodedThreshold
-    }
   }
 
   enum CodingKeys: String, CodingKey {
@@ -180,3 +140,59 @@ public struct SafetySetting: Codable {
     self.threshold = threshold
   }
 }
+
+// MARK: - Codable Conformances
+
+@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
+extension SafetyRating.HarmProbability: Codable {
+  public init(from decoder: Decoder) throws {
+    let value = try decoder.singleValueContainer().decode(String.self)
+    guard let decodedProbability = SafetyRating.HarmProbability(rawValue: value) else {
+      Logging.default
+        .error("[GoogleGenerativeAI] Unrecognized HarmProbability with value \"\(value)\".")
+      self = .unknown
+      return
+    }
+
+    self = decodedProbability
+  }
+}
+
+@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
+extension SafetyRating: Decodable {}
+
+@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
+extension SafetyFeedback: Decodable {}
+
+@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
+extension SafetySetting.HarmCategory: Codable {
+  public init(from decoder: Decoder) throws {
+    let value = try decoder.singleValueContainer().decode(String.self)
+    guard let decodedCategory = SafetySetting.HarmCategory(rawValue: value) else {
+      Logging.default
+        .error("[GoogleGenerativeAI] Unrecognized HarmCategory with value \"\(value)\".")
+      self = .unknown
+      return
+    }
+
+    self = decodedCategory
+  }
+}
+
+@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
+extension SafetySetting.BlockThreshold: Codable {
+  public init(from decoder: Decoder) throws {
+    let value = try decoder.singleValueContainer().decode(String.self)
+    guard let decodedThreshold = SafetySetting.BlockThreshold(rawValue: value) else {
+      Logging.default
+        .error("[GoogleGenerativeAI] Unrecognized BlockThreshold with value \"\(value)\".")
+      self = .unknown
+      return
+    }
+
+    self = decodedThreshold
+  }
+}
+
+@available(iOS 15.0, macOS 11.0, macCatalyst 15.0, *)
+extension SafetySetting: Codable {}