[SyntaxLayout] Eliminate childName(_:AnyKeyPath)

Replace with SyntaxLayoutProperty.name

Author: rintaro

CodeGeneration/Sources/generate-swift-syntax/templates/swiftsyntax/ChildNameForKeyPathFile.swift

@@ -15,32 +15,28 @@ import SwiftSyntaxBuilder
 import SyntaxSupport
 import Utils
 
-let childNameForKeyPathFile = SourceFileSyntax(leadingTrivia: copyrightHeader) {
-  try! FunctionDeclSyntax(
-    """
-    /// If the keyPath is one from a layout structure, return the property name
-    /// of it.
-    @_spi(RawSyntax)
-    public func childName(_ keyPath: AnyKeyPath) -> String?
-    """
-  ) {
-    try! SwitchExprSyntax("switch keyPath") {
-      for node in NON_BASE_SYNTAX_NODES.compactMap(\.layoutNode) {
-        for child in node.children {
-          SwitchCaseSyntax(
-            """
-            case \\\(node.type.syntaxBaseName).\(child.memberCallName):
-              return \(literal: child.identifier.description)
-            """
-          )
+let childNameForKeyPathFile = try! SourceFileSyntax(leadingTrivia: copyrightHeader) {
+  try ExtensionDeclSyntax("extension SyntaxLayoutProperty") {
+    try VariableDeclSyntax(
+      """
+      /// Property name if this is a valid property.
+      /// 'nil' if the `baseKind` is not a layout syntax, or the index is out of range.
+      @_spi(RawSyntax)
+      public var name: String?
+      """
+    ) {
+      try SwitchExprSyntax("switch (self.baseKind, self.index.value)") {
+        for node in NON_BASE_SYNTAX_NODES {
+          if let layoutNode = node.layoutNode {
+            for (index, child) in layoutNode.children.enumerated() {
+              SwitchCaseSyntax("case (.\(node.enumCaseCallName), \(literal: index)):") {
+                StmtSyntax("return \(literal: child.identifier.description)")
+              }
+            }
+          }
         }
+        SwitchCaseSyntax("default: return nil")
       }
-      SwitchCaseSyntax(
-        """
-        default:
-          return nil
-        """
-      )
     }
   }
 }

Sources/SwiftSyntax/SyntaxProtocol.swift

@@ -731,7 +731,7 @@ extension SyntaxProtocol {
       target.write("\n")
       target.write(indentString)
       target.write(isLastChild ? "╰─" : "├─")
-      if let keyPath = child.keyPathInParent, let name = childName(keyPath) {
+      if let property = child.propertyInParent, let name = property.name {
         target.write("\(name): ")
       } else if self.kind.isSyntaxCollection {
         target.write("[\(num)]: ")