Extract Codable conformance of RawSyntax into an extension

Sources/SwiftSyntax/RawSyntax.swift

@@ -85,7 +85,7 @@ fileprivate enum RawSyntaxData {
 /// Represents the raw tree structure underlying the syntax tree. These nodes
 /// have no notion of identity and only provide structure to the tree. They
 /// are immutable and can be freely shared between syntax nodes.
-struct RawSyntax: Codable {
+struct RawSyntax {
   fileprivate let data: RawSyntaxData
   let presence: SourcePresence
 
@@ -198,61 +198,6 @@ struct RawSyntax: Codable {
     case nodeLookupFailed(SyntaxNodeId)
   }
 
-  /// Creates a RawSyntax from the provided Foundation Decoder.
-  init(from decoder: Decoder) throws {
-    let container = try decoder.container(keyedBy: CodingKeys.self)
-    let id = try container.decodeIfPresent(SyntaxNodeId.self, forKey: .id)
-    let omitted = try container.decodeIfPresent(Bool.self, forKey: .omitted) ?? false
-
-    if omitted {
-      guard let id = id else {
-        throw IncrementalDecodingError.omittedNodeHasNoId
-      }
-      guard let lookupFunc = decoder.userInfo[.omittedNodeLookupFunction] as?
-                               (SyntaxNodeId) -> RawSyntax? else {
-        throw IncrementalDecodingError.noLookupFunctionPassed
-      }
-      guard let lookupNode = lookupFunc(id) else {
-        throw IncrementalDecodingError.nodeLookupFailed(id)
-      }
-      self = lookupNode
-      return
-    }
-
-    let presence = try container.decode(SourcePresence.self, forKey: .presence)
-    if let kind = try container.decodeIfPresent(SyntaxKind.self, forKey: .kind) {
-      let layout = try container.decode([RawSyntax?].self, forKey: .layout)
-      self.init(kind: kind, layout: layout, presence: presence, id: id)
-    } else {
-      let kind = try container.decode(TokenKind.self, forKey: .tokenKind)
-      let leadingTrivia = try container.decode(Trivia.self, forKey: .leadingTrivia)
-      let trailingTrivia = try container.decode(Trivia.self, forKey: .trailingTrivia)
-      self.init(kind: kind, leadingTrivia: leadingTrivia,
-                trailingTrivia: trailingTrivia, presence: presence, id: id)
-    }
-    if let callback = decoder.userInfo[.rawSyntaxDecodedCallback] as?
-                        (RawSyntax) -> Void {
-      callback(self)
-    }
-  }
-
-  /// Encodes the RawSyntax to the provided Foundation Encoder.
-  func encode(to encoder: Encoder) throws {
-    var container = encoder.container(keyedBy: CodingKeys.self)
-    switch self.data {
-    case let .node(kind, layout):
-      try container.encode(id, forKey: .id)
-      try container.encode(kind, forKey: .kind)
-      try container.encode(layout, forKey: .layout)
-    case let .token(kind, leadingTrivia, trailingTrivia):
-      try container.encode(id, forKey: .id)
-      try container.encode(kind, forKey: .tokenKind)
-      try container.encode(leadingTrivia, forKey: .leadingTrivia)
-      try container.encode(trailingTrivia, forKey: .trailingTrivia)
-    }
-    try container.encode(presence, forKey: .presence)
-  }
-
   /// Creates a RawSyntax node that's marked missing in the source with the
   /// provided kind and layout.
   /// - Parameters:
@@ -389,6 +334,63 @@ extension RawSyntax {
   }
 }
 
+extension RawSyntax: Codable {
+  /// Creates a RawSyntax from the provided Foundation Decoder.
+  init(from decoder: Decoder) throws {
+    let container = try decoder.container(keyedBy: CodingKeys.self)
+    let id = try container.decodeIfPresent(SyntaxNodeId.self, forKey: .id)
+    let omitted = try container.decodeIfPresent(Bool.self, forKey: .omitted) ?? false
+
+    if omitted {
+      guard let id = id else {
+        throw IncrementalDecodingError.omittedNodeHasNoId
+      }
+      guard let lookupFunc = decoder.userInfo[.omittedNodeLookupFunction] as?
+                               (SyntaxNodeId) -> RawSyntax? else {
+        throw IncrementalDecodingError.noLookupFunctionPassed
+      }
+      guard let lookupNode = lookupFunc(id) else {
+        throw IncrementalDecodingError.nodeLookupFailed(id)
+      }
+      self = lookupNode
+      return
+    }
+
+    let presence = try container.decode(SourcePresence.self, forKey: .presence)
+    if let kind = try container.decodeIfPresent(SyntaxKind.self, forKey: .kind) {
+      let layout = try container.decode([RawSyntax?].self, forKey: .layout)
+      self.init(kind: kind, layout: layout, presence: presence, id: id)
+    } else {
+      let kind = try container.decode(TokenKind.self, forKey: .tokenKind)
+      let leadingTrivia = try container.decode(Trivia.self, forKey: .leadingTrivia)
+      let trailingTrivia = try container.decode(Trivia.self, forKey: .trailingTrivia)
+      self.init(kind: kind, leadingTrivia: leadingTrivia,
+                trailingTrivia: trailingTrivia, presence: presence, id: id)
+    }
+    if let callback = decoder.userInfo[.rawSyntaxDecodedCallback] as?
+                        (RawSyntax) -> Void {
+      callback(self)
+    }
+  }
+
+  /// Encodes the RawSyntax to the provided Foundation Encoder.
+  func encode(to encoder: Encoder) throws {
+    var container = encoder.container(keyedBy: CodingKeys.self)
+    switch self.data {
+    case let .node(kind, layout):
+      try container.encode(id, forKey: .id)
+      try container.encode(kind, forKey: .kind)
+      try container.encode(layout, forKey: .layout)
+    case let .token(kind, leadingTrivia, trailingTrivia):
+      try container.encode(id, forKey: .id)
+      try container.encode(kind, forKey: .tokenKind)
+      try container.encode(leadingTrivia, forKey: .leadingTrivia)
+      try container.encode(trailingTrivia, forKey: .trailingTrivia)
+    }
+    try container.encode(presence, forKey: .presence)
+  }
+}
+
 extension RawSyntax: ByteTreeObjectDecodable {
   enum SyntaxType: UInt8, ByteTreeScalarDecodable {
     case token = 0