Move extension to another file

Author: Pouya Yarandi

Sources/SwiftProtobuf/Applying.swift

@@ -292,16 +292,3 @@ internal struct ApplyingDecoder: Decoder {
   }
 
 }
-
-public extension Message {
-  func applying(_ value: Any, for fieldNumber: Int) throws -> Self {
-    var copy = self
-    try copy.apply(value, for: fieldNumber)
-    return copy
-  }
-
-  mutating func apply(_ value: Any, for fieldNumber: Int) throws {
-    var decoder = ApplyingDecoder(fieldNumber: fieldNumber, value: value)
-    try decodeMessage(decoder: &decoder)
-  }
-}

Sources/SwiftProtobuf/Message+Applying.swift

@@ -0,0 +1,40 @@
+// Sources/SwiftProtobuf/Message+Applying.swift - Applying feature
+//
+// Copyright (c) 2014 - 2017 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
+//
+// -----------------------------------------------------------------------------
+///
+/// Extends the `Message` type with applying behavior.
+///
+// -----------------------------------------------------------------------------
+
+public extension Message {
+
+  /// Applies a value for a specific `fieldNumber` of the message
+  /// and returns a copy of it.
+  ///
+  /// - Parameters:
+  ///   - value: The value to be applied.
+  ///   - fieldNumber: Protobuf index of the field that the value should be applied for.
+  /// - Returns: A copy of the message with applied value.
+  func applying(_ value: Any, for fieldNumber: Int) throws -> Self {
+    var copy = self
+    try copy.apply(value, for: fieldNumber)
+    return copy
+  }
+
+  /// Applies a value for a specific `fieldNumber` of the message without
+  /// making a copy. This method mutates the original message.
+  ///
+  /// - Parameters:
+  ///   - value: The value to be applied.
+  ///   - fieldNumber: Protobuf index of the field that the value should be applied for.
+  mutating func apply(_ value: Any, for fieldNumber: Int) throws {
+    var decoder = ApplyingDecoder(fieldNumber: fieldNumber, value: value)
+    try decodeMessage(decoder: &decoder)
+  }
+}