Remove copy mechanism in some functions

Author: Pouya Yarandi

Sources/SwiftProtobuf/GetPathDecoder.swift

@@ -1,6 +1,6 @@
 // Sources/SwiftProtobuf/GetPathDecoder.swift - Path decoder (Getter)
 //
-// Copyright (c) 2014 - 2016 Apple Inc. and the project authors
+// Copyright (c) 2014 - 2023 Apple Inc. and the project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See LICENSE.txt for license information:
@@ -16,7 +16,7 @@ import Foundation
 
 struct GetPathDecoder<T: Message>: Decoder {
 
-  private let path: String
+  private let nextPath: [String]
   private var number: Int?
 
   private var _value: Any?
@@ -30,19 +30,11 @@ struct GetPathDecoder<T: Message>: Decoder {
     _hasPath
   }
 
-  internal init(path: String) {
-    self.path = path
-    if let firstPathComponent {
-      self.number = T.number(for: firstPathComponent)
+  internal init(path: [String]) {
+    if let firstComponent = path.first {
+      self.number = T.number(for: firstComponent)
     }
-  }
-
-  private var firstPathComponent: String? {
-    path.components(separatedBy: ".").first
-  }
-
-  private var nextPath: String {
-    path.components(separatedBy: ".").dropFirst().joined(separator: ".")
+    self.nextPath = .init(path.dropFirst())
   }
 
   mutating func handleConflictingOneOf() throws {}
@@ -309,17 +301,17 @@ struct GetPathDecoder<T: Message>: Decoder {
 }
 
 extension Message {
-  func `get`(path: String) throws -> Any? {
-    var copy = self
-    var decoder = GetPathDecoder<Self>(path: path)
-    try copy.decodeMessage(decoder: &decoder)
+  mutating func `get`(path: String) throws -> Any? {
+    let _path = path.components(separatedBy: ".")
+    var decoder = GetPathDecoder<Self>(path: _path)
+    try decodeMessage(decoder: &decoder)
     return decoder.value
   }
 
-  func hasPath(path: String) -> Bool {
-    var copy = self
-    var decoder = GetPathDecoder<Self>(path: path)
-    try? copy.decodeMessage(decoder: &decoder)
+  mutating func hasPath(path: String) -> Bool {
+    let _path = path.components(separatedBy: ".")
+    var decoder = GetPathDecoder<Self>(path: _path)
+    try? decodeMessage(decoder: &decoder)
     return decoder.hasPath
   }
 }

Sources/SwiftProtobuf/Google_Protobuf_FieldMask+Extensions.swift

@@ -351,7 +351,7 @@ extension Google_Protobuf_FieldMask {
   public func isValid<M: Message & _ProtoNameProviding>(
     for messageType: M.Type
   ) -> Bool {
-    let message = M()
+    var message = M()
     return paths.allSatisfy { path in
       message.isPathValid(path)
     }

Sources/SwiftProtobuf/Message+FieldMask.swift

@@ -1,6 +1,6 @@
 // Sources/SwiftProtobuf/Message+FieldMask.swift - Message field mask extensions
 //
-// Copyright (c) 2014 - 2016 Apple Inc. and the project authors
+// Copyright (c) 2014 - 2023 Apple Inc. and the project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See LICENSE.txt for license information:
@@ -23,10 +23,11 @@ extension Message {
   public static func isPathValid(
     _ path: String
   ) -> Bool {
-    Self().hasPath(path: path)
+    var message = Self()
+    return message.hasPath(path: path)
   }
 
-  internal func isPathValid(
+  internal mutating func isPathValid(
     _ path: String
   ) -> Bool {
     hasPath(path: path)
@@ -44,6 +45,7 @@ extension Message {
     to source: Self,
     fieldMask: Google_Protobuf_FieldMask
   ) throws {
+    var source = source
     var copy = self
     var pathToValueMap: [String: Any?] = [:]
     for path in fieldMask.paths {

Sources/SwiftProtobuf/SetPathDecoder.swift

@@ -1,6 +1,6 @@
 // Sources/SwiftProtobuf/SetPathDecoder.swift - Path decoder (Setter)
 //
-// Copyright (c) 2014 - 2016 Apple Inc. and the project authors
+// Copyright (c) 2014 - 2023 Apple Inc. and the project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See LICENSE.txt for license information:
@@ -35,29 +35,16 @@ extension Message {
 
 struct SetPathDecoder<T: Message>: Decoder {
 
-  private let path: String
   private let value: Any?
   private var number: Int?
+  private let nextPath: [String]
 
-  init(path: String, value: Any?) {
-    self.path = path
-    self.value = value
-    if let firstPathComponent {
-      self.number = T.number(for: firstPathComponent)
+  init(path: [String], value: Any?) {
+    if let firstComponent = path.first {
+      self.number = T.number(for: firstComponent)
     }
-  }
-
-  var firstPathComponent: String? {
-    return path
-          .components(separatedBy: ".")
-          .first
-  }
-
-  var nextPath: String {
-    return path
-          .components(separatedBy: ".")
-          .dropFirst()
-          .joined(separator: ".")
+    self.nextPath = .init(path.dropFirst())
+    self.value = value
   }
 
   func _value<V>(as: V.Type) throws -> V {
@@ -337,7 +324,8 @@ struct SetPathDecoder<T: Message>: Decoder {
 
 extension Message {
   mutating func `set`(path: String, value: Any?) throws {
-    var decoder = SetPathDecoder<Self>(path: path, value: value)
+    let _path = path.components(separatedBy: ".")
+    var decoder = SetPathDecoder<Self>(path: _path, value: value)
     try decodeMessage(decoder: &decoder)
   }
 }