[5.3] Introduce a syntaxNodeType property for all types conforming to SyntaxProtocol

Sources/SwiftSyntax/Syntax.swift

@@ -58,6 +58,10 @@ extension Syntax {
   public func `as`<S: SyntaxProtocol>(_ syntaxType: S.Type) -> S? {
     return S.init(self)
   }
+
+  public var syntaxNodeType: SyntaxProtocol.Type {
+    return Swift.type(of: self.asProtocol(SyntaxProtocol.self))
+  }
 }
 
 extension Syntax: CustomReflectable {
@@ -101,6 +105,9 @@ public protocol SyntaxProtocol: CustomStringConvertible,
   /// integrity after it has been rewritten by the syntax rewriter.
   /// Results in an assertion failure if the layout is invalid.
   func _validateLayout()
+
+  /// Returns the underlying syntax node type.
+  var syntaxNodeType: SyntaxProtocol.Type { get }
 }
 
 internal extension SyntaxProtocol {

Sources/SwiftSyntax/SyntaxBaseNodes.swift.gyb

@@ -99,6 +99,10 @@ public struct ${node.name}: ${node.name}Protocol, SyntaxHashable {
     self._syntaxNode = Syntax(data)
   }
 
+  public var syntaxNodeType: SyntaxProtocol.Type {
+    return _syntaxNode.syntaxNodeType
+  }
+
   public func _validateLayout() {
     // Check the layout of the concrete type
     return Syntax(self)._validateLayout()

Sources/SwiftSyntax/SyntaxCollections.swift.gyb

@@ -55,6 +55,10 @@ public struct ${node.name}: SyntaxCollection, SyntaxHashable {
     self._syntaxNode = Syntax(data)
   }
 
+  public var syntaxNodeType: SyntaxProtocol.Type {
+    return Swift.type(of: self)
+  }
+
   /// The number of elements, `present` or `missing`, in this collection.
   public var count: Int { return raw.numberOfChildren }
 

Sources/SwiftSyntax/SyntaxNodes.swift.gyb.template

@@ -79,6 +79,10 @@ public struct ${node.name}: ${base_type}Protocol, SyntaxHashable {
     assert(data.raw.kind == .${node.swift_syntax_kind})
     self._syntaxNode = Syntax(data)
   }
+
+  public var syntaxNodeType: SyntaxProtocol.Type {
+    return Swift.type(of: self)
+  }
 %     for child in node.children:
 %       child_node = NODE_MAP.get(child.syntax_kind)
 %

Sources/SwiftSyntax/SyntaxOtherNodes.swift

@@ -25,6 +25,10 @@ public struct UnknownSyntax: SyntaxProtocol, SyntaxHashable {
     self._syntaxNode = syntax
   }
 
+  public var syntaxNodeType: SyntaxProtocol.Type {
+    return Swift.type(of: self)
+  }
+
   public func _validateLayout() {
     // We are verifying an unknown node. Since we don’t know anything about it
     // we need to assume it’s valid.
@@ -66,6 +70,10 @@ public struct TokenSyntax: SyntaxProtocol, SyntaxHashable {
     self._syntaxNode = Syntax(data)
   }
 
+  public var syntaxNodeType: SyntaxProtocol.Type {
+    return Swift.type(of: self)
+  }
+
   public func _validateLayout() {
     /// A token is always valid as it has no children. Nothing to do here.
   }

Sources/SwiftSyntax/gyb_generated/SyntaxBaseNodes.swift

@@ -80,6 +80,10 @@ public struct DeclSyntax: DeclSyntaxProtocol, SyntaxHashable {
     self._syntaxNode = Syntax(data)
   }
 
+  public var syntaxNodeType: SyntaxProtocol.Type {
+    return _syntaxNode.syntaxNodeType
+  }
+
   public func _validateLayout() {
     // Check the layout of the concrete type
     return Syntax(self)._validateLayout()
@@ -184,6 +188,10 @@ public struct ExprSyntax: ExprSyntaxProtocol, SyntaxHashable {
     self._syntaxNode = Syntax(data)
   }
 
+  public var syntaxNodeType: SyntaxProtocol.Type {
+    return _syntaxNode.syntaxNodeType
+  }
+
   public func _validateLayout() {
     // Check the layout of the concrete type
     return Syntax(self)._validateLayout()
@@ -288,6 +296,10 @@ public struct StmtSyntax: StmtSyntaxProtocol, SyntaxHashable {
     self._syntaxNode = Syntax(data)
   }
 
+  public var syntaxNodeType: SyntaxProtocol.Type {
+    return _syntaxNode.syntaxNodeType
+  }
+
   public func _validateLayout() {
     // Check the layout of the concrete type
     return Syntax(self)._validateLayout()
@@ -392,6 +404,10 @@ public struct TypeSyntax: TypeSyntaxProtocol, SyntaxHashable {
     self._syntaxNode = Syntax(data)
   }
 
+  public var syntaxNodeType: SyntaxProtocol.Type {
+    return _syntaxNode.syntaxNodeType
+  }
+
   public func _validateLayout() {
     // Check the layout of the concrete type
     return Syntax(self)._validateLayout()
@@ -496,6 +512,10 @@ public struct PatternSyntax: PatternSyntaxProtocol, SyntaxHashable {
     self._syntaxNode = Syntax(data)
   }
 
+  public var syntaxNodeType: SyntaxProtocol.Type {
+    return _syntaxNode.syntaxNodeType
+  }
+
   public func _validateLayout() {
     // Check the layout of the concrete type
     return Syntax(self)._validateLayout()