Separate applying file

Author: Pouya Yarandi

Sources/SwiftProtobuf/Applying.swift

@@ -0,0 +1,46 @@
+//
+// Sources/SwiftProtobuf/Applying.swift - Applying protocol and errors
+//
+// Copyright (c) 2023 Apple Inc. and the project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See LICENSE.txt for license information:
+// https://github.com/apple/swift-protobuf/blob/main/LICENSE.txt
+//
+// -----------------------------------------------------------------------------
+///
+/// Applying feature (including protocol and errors)
+///
+// -----------------------------------------------------------------------------
+
+/// Describes errors can occure during applying a value to proto
+public enum ProtoApplyingError: Error {
+
+  /// Describes a mismatch in type of the field
+  ///
+  /// If a value of type A is applied to a fieldNumber with type B
+  /// this error will be thrown by the applying() method.
+  case typeMismatch
+
+  /// Describes that the fieldNumber is not valid
+  ///
+  /// If a value is applied to an undefined fieldNumber of the model
+  /// this error will be thrown by the applying() method.
+  case invalidFieldNumber
+}
+
+public protocol _ProtoApplying: Message {
+
+  /// Applies a value on a particular field of a protobuf Message
+  /// In cases that value is not appliable, an ProtoApplyingError will be thrown.
+  ///
+  /// If you wish to use this method, the Applying option in protoc should
+  /// be set to true, so that the applying method will be generated for all
+  /// the protobuf Messages.
+  ///
+  /// - Parameters:
+  ///   - value: any value to be applied on a particular field
+  ///   - fieldNumber: integer index refering to a field of proto model
+  /// - Returns: a copy of the model which the value has been applied on it.
+  func applying(_ value: Any, for fieldNumber: Int) throws -> Self
+}

Sources/SwiftProtobuf/CMakeLists.txt

@@ -3,6 +3,7 @@ add_library(SwiftProtobuf
   AnyMessageStorage.swift
   AnyUnpackError.swift
   api.pb.swift
+  Applying.swift
   BinaryDecoder.swift
   BinaryDecodingError.swift
   BinaryDecodingOptions.swift

Sources/SwiftProtobuf/ProtobufMirror.swift

@@ -303,12 +303,3 @@ public extension ProtobufMirror {
   }
 
 }
-
-public enum ProtoApplyingError: Error {
-  case typeMismatch
-  case invalidFieldNumber
-}
-
-public protocol _ProtoApplying: Message {
-  func applying(_ value: Any, for fieldNumber: Int) throws -> Self
-}