[RFC] Swift Macro support for Node boilerplate

Lexical/Core/Editor.swift

@@ -799,7 +799,7 @@ public class Editor: NSObject {
       for nodeKey in nodesToProcess where nodeKey != compositionKey && nodeKey != rootNode.key {
         guard
           let node = getNodeByKey(key: nodeKey),
-          let transforms = nodeTransforms[node.type],
+          let transforms = nodeTransforms[type(of: node).type],
           node.isAttached()
         else {
           continue

Lexical/Core/LexicalMacros.swift

@@ -0,0 +1,11 @@
+//
+//  File.swift
+//  
+//
+//  Created by Amy Worrall on 18/07/2023.
+//
+
+import Foundation
+
+@attached(member, names: arbitrary)
+public macro LexicalNode(_ type: NodeType) = #externalMacro(module: "LexicalMacrosBase", type: "NodeMacro")

Lexical/Core/Nodes/CodeHighlightNode.swift

@@ -14,23 +14,24 @@ public class CodeHighlightNode: TextNode {
 
   public var highlightType: String?
 
+  open override class var type: NodeType {
+    .codeHighlight
+  }
+
   override public init() {
     super.init()
-    self.type = NodeType.codeHighlight
   }
 
   required init(text: String, highlightType: String?, key: NodeKey? = nil) {
     super.init(text: text, key: key)
     self.highlightType = highlightType
-    self.type = NodeType.codeHighlight
   }
 
   public required init(from decoder: Decoder) throws {
     let container = try decoder.container(keyedBy: CodingKeys.self)
     try super.init(from: decoder)
 
     self.highlightType = try container.decode(String.self, forKey: .highlightType)
-    self.type = NodeType.codeHighlight
   }
 
   public required convenience init(text: String, key: NodeKey?) {

Lexical/Core/Nodes/CodeNode.swift

@@ -42,23 +42,24 @@ public class CodeNode: ElementNode {
 
   private var language: String = ""
 
+  open override class var type: NodeType {
+    .code
+  }
+
   override public init() {
     super.init()
-    self.type = NodeType.code
   }
 
   required init(language: String, key: NodeKey? = nil) {
     super.init(key)
     self.language = language
-    self.type = NodeType.code
   }
 
   public required init(from decoder: Decoder) throws {
     let container = try decoder.container(keyedBy: CodingKeys.self)
     try super.init(from: decoder)
 
     self.language = try container.decode(String.self, forKey: .language)
-    self.type = NodeType.code
   }
 
   override public func encode(to encoder: Encoder) throws {

Lexical/Core/Nodes/HeadingNode.swift

@@ -23,49 +23,10 @@ enum HeadingDefaultFontSize: Float {
   case h5 = 20
 }
 
+@LexicalNode(.heading)
 public class HeadingNode: ElementNode {
-  enum CodingKeys: String, CodingKey {
-    case tag
-  }
-
-  private var tag: HeadingTagType
-
-  // MARK: - Init
-
-  public init(tag: HeadingTagType) {
-    self.tag = tag
-
-    super.init()
-    self.type = NodeType.heading
-  }
-
-  public required init(_ key: NodeKey?, tag: HeadingTagType) {
-    self.tag = tag
-    super.init(key)
-    self.type = NodeType.heading
-  }
 
-  public required init(from decoder: Decoder) throws {
-    let container = try decoder.container(keyedBy: CodingKeys.self)
-    self.tag = try container.decode(HeadingTagType.self, forKey: .tag)
-    try super.init(from: decoder)
-
-    self.type = NodeType.heading
-  }
-
-  override public func encode(to encoder: Encoder) throws {
-    try super.encode(to: encoder)
-    var container = encoder.container(keyedBy: CodingKeys.self)
-    try container.encode(self.tag, forKey: .tag)
-  }
-
-  public func getTag() -> HeadingTagType {
-    tag
-  }
-
-  override public func clone() -> Self {
-    Self(key, tag: tag)
-  }
+  private var _tag: HeadingTagType
 
   override public func getAttributedStringAttributes(theme: Theme) -> [NSAttributedString.Key: Any] {
     switch tag {

Lexical/Core/Nodes/LineBreakNode.swift

@@ -6,19 +6,21 @@
  */
 
 public class LineBreakNode: Node {
+
+  open override class var type: NodeType {
+    .linebreak
+  }
+
   override public init() {
     super.init()
-    self.type = NodeType.linebreak
   }
 
   override required init(_ key: NodeKey?) {
     super.init(key)
-    self.type = NodeType.linebreak
   }
 
   public required init(from decoder: Decoder) throws {
     try super.init(from: decoder)
-    self.type = NodeType.linebreak
   }
 
   override public func encode(to encoder: Encoder) throws {

Lexical/Core/Nodes/Node.swift

@@ -20,21 +20,26 @@ open class Node: Codable {
     case version
   }
 
+  open class var type: NodeType {
+    .unknown
+  }
+
+  public func getType() -> NodeType {
+    return Swift.type(of: self).type
+  }
+
   public var key: NodeKey
   var parent: NodeKey?
-  public var type: NodeType
   public var version: Int
 
   public init() {
-    self.type = Node.getType()
     self.version = 1
     self.key = LexicalConstants.uninitializedNodeKey
 
     _ = try? generateKey(node: self)
   }
 
   public init(_ key: NodeKey?) {
-    self.type = Node.getType()
     self.version = 1
 
     if let key, key != LexicalConstants.uninitializedNodeKey {
@@ -49,7 +54,6 @@ open class Node: Codable {
   public required init(from decoder: Decoder) throws {
     let values = try decoder.container(keyedBy: CodingKeys.self)
     key = LexicalConstants.uninitializedNodeKey
-    type = try NodeType(rawValue: values.decode(String.self, forKey: .type))
     version = try values.decode(Int.self, forKey: .version)
 
     _ = try? generateKey(node: self)
@@ -58,7 +62,7 @@ open class Node: Codable {
   /// Used when serialising node to JSON
   open func encode(to encoder: Encoder) throws {
     var container = encoder.container(keyedBy: CodingKeys.self)
-    try container.encode(self.type.rawValue, forKey: .type)
+    try container.encode(Self.type.rawValue, forKey: .type)
     try container.encode(self.version, forKey: .version)
   }
 
@@ -68,13 +72,6 @@ open class Node: Codable {
    */
   open func didMoveTo(newEditor editor: Editor) {}
 
-  // This is an initial value for `type`.
-  // static methods cannot be overridden in swift so,
-  // each subclass needs to assign the type property in their init method
-  static func getType() -> NodeType {
-    NodeType.unknown
-  }
-
   /// Provides the **preamble** part of the node's content. Typically the preamble is used for control characters to represent embedded objects (see ``DecoratorNode``).
   ///
   /// In Lexical iOS, a node's content is split into four parts: preamble, children, text, postamble. ``ElementNode`` subclasses can implement preamble/postamble, and TextNode subclasses can implement the text part.
@@ -137,7 +134,7 @@ open class Node: Codable {
    Lexical's paragraph nodes!)
    */
   open func getBlockLevelAttributes(theme: Theme) -> BlockLevelAttributes? {
-    return theme.getBlockLevelAttributes(self.type)
+    return theme.getBlockLevelAttributes(Self.type)
   }
 
   /// Returns a mutable version of the node. Will throw an error if called outside of a Lexical Editor ``Editor/update(_:)`` callback.

Lexical/Core/Nodes/ParagraphNode.swift

@@ -8,19 +8,20 @@
 import UIKit
 
 public class ParagraphNode: ElementNode {
+  open override class var type: NodeType {
+    .paragraph
+  }
+
   override public init() {
     super.init()
-    self.type = NodeType.paragraph
   }
 
   override required init(_ key: NodeKey?) {
     super.init(key)
-    self.type = NodeType.paragraph
   }
 
   public required init(from decoder: Decoder) throws {
     try super.init(from: decoder)
-    self.type = NodeType.paragraph
   }
 
   override public func encode(to encoder: Encoder) throws {

Lexical/Core/Nodes/QuoteNode.swift

@@ -8,20 +8,20 @@
 import UIKit
 
 public class QuoteNode: ElementNode {
+  open override class var type: NodeType {
+    .quote
+  }
+
   override public init() {
     super.init()
-    self.type = NodeType.quote
   }
 
   override public required init(_ key: NodeKey?) {
     super.init(key)
-    self.type = NodeType.quote
   }
 
   public required init(from decoder: Decoder) throws {
     try super.init(from: decoder)
-
-    self.type = NodeType.quote
   }
 
   override public func encode(to encoder: Encoder) throws {

Lexical/Core/Nodes/RootNode.swift

@@ -9,14 +9,16 @@ import UIKit
 
 public class RootNode: ElementNode {
 
+  open override class var type: NodeType {
+    .root
+  }
+
   override required init() {
     super.init(kRootNodeKey)
-    self.type = NodeType.root
   }
 
   public required init(from decoder: Decoder) throws {
     try super.init(from: decoder)
-    self.type = NodeType.root
   }
 
   override public func encode(to encoder: Encoder) throws {

Lexical/Core/Nodes/TextNode.swift

@@ -198,15 +198,17 @@ open class TextNode: Node {
   var detail = TextNodeDetail()
   var style: String = ""
 
+  open override class var type: NodeType {
+    .text
+  }
+
   override public init() {
     super.init()
-    self.type = NodeType.text
   }
 
   public required init(text: String, key: NodeKey?) {
     super.init(key)
     self.text = text
-    self.type = NodeType.text
   }
 
   public convenience init(text: String) {
@@ -224,7 +226,6 @@ open class TextNode: Node {
     let serializedDetail = try container.decode(SerializedTextNodeDetail.self, forKey: .detail)
     self.detail = SerializedTextNodeDetail.convertToTextDetail(from: serializedDetail)
     self.style = try container.decode(String.self, forKey: .style)
-    self.type = NodeType.text
   }
 
   override open func encode(to encoder: Encoder) throws {
@@ -530,7 +531,7 @@ open class TextNode: Node {
   }
 
   public func isSimpleText() -> Bool {
-    return type == NodeType.text && mode == .normal
+    return getType() == .text && mode == .normal
   }
 
   @discardableResult

Lexical/Core/Nodes/UnknownNode.swift

@@ -111,6 +111,8 @@ public class UnknownNode: Node {
     }
   }
 
+  private var type: NodeType = .unknown
+
   public required init(from decoder: Decoder) throws {
     let container = try decoder.singleValueContainer()
 

Lexical/Core/TextUtils.swift

@@ -41,7 +41,7 @@ internal func canShowPlaceholder(isComposing: Bool) -> Bool {
   for childNode in children {
     guard let childNode = childNode as? ElementNode else { return true }
 
-    if childNode.type != NodeType.paragraph {
+    if type(of: childNode).type != NodeType.paragraph {
       return false
     }
 

Lexical/Core/Utils.swift

@@ -271,9 +271,9 @@ public func getNodeHierarchy(editorState: EditorState?) throws -> String {
         } else {
           formatString = ""
         }
-        description.append("\(indentation)(\(node.key)) \(node.type.rawValue) \"\(textNode.getTextPart())\" \(formatString)")
+        description.append("\(indentation)(\(node.key)) \(type(of: node).type.rawValue) \"\(textNode.getTextPart())\" \(formatString)")
       } else {
-        description.append("\(indentation)(\(node.key)) \(node.type.rawValue)")
+        description.append("\(indentation)(\(node.key)) \(type(of: node).type.rawValue)")
       }
 
       if let elementNode = node as? ElementNode {
@@ -283,7 +283,7 @@ public func getNodeHierarchy(editorState: EditorState?) throws -> String {
     } while !currentNodes.isEmpty
 
     hierarchyString = description.joined(separator: "\n")
-    cacheString = sortedNodeMap.map({ node in "\(node.key): \(node.value.type)" }).joined(separator: ", ")
+    cacheString = sortedNodeMap.map({ node in "\(node.key): \(type(of: node.value).type)" }).joined(separator: ", ")
   }
 
   return "Tree:\n\(hierarchyString)\nCache:\n\(cacheString)"
@@ -463,7 +463,7 @@ public func getNearestNodeOfType<T: ElementNode>(
   var parent: Node? = node
 
   while let unwrappedParent = parent {
-    if unwrappedParent.type == type, let typedParent = unwrappedParent as? T {
+    if unwrappedParent.getType() == type, let typedParent = unwrappedParent as? T {
       return typedParent as T
     }