Build new IR for functions returning a constant

sdk/lib/_internal/compiler/implementation/ir/ir_nodes.dart

+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// IrNodes are kept in a separate library to have precise control over their
+// dependencies on other parts of the system
+library ir_nodes;
+
+import '../dart2jslib.dart' show Constant;
+
+/**
+ * A pair of source offset and an identifier name. Identifier names are used in
+ * the Javascript backend to generate source maps.
+ */
+class PositionWithIdentifierName {
+  final int offset;
+  final String sourceName;
+  PositionWithIdentifierName(this.offset, this.sourceName);
+}
+
+abstract class IrNode {
+  final /* int | PositionWithIdentifierName */ position;
+
+  const IrNode(this.position);
+
+  int get offset =>
+      (position is PositionWithIdentifierName) ? position.offset : position;
+
+  String get sourceName =>
+      (position is PositionWithIdentifierName) ? position.sourceName : null;
+
+  accept(IrNodesVisitor visitor);
+}
+
+class IrFunction extends IrNode {
+  final List<IrNode> statements;
+
+  final int endOffset;
+  final int namePosition;
+
+  IrFunction(position, this.endOffset, this.namePosition, this.statements)
+    : super(position);
+
+  accept(IrNodesVisitor visitor) => visitor.visitIrFunction(this);
+}
+
+class IrReturn extends IrNode {
+  final IrNode value;
+
+  IrReturn(position, this.value) : super(position);
+
+  accept(IrNodesVisitor visitor) => visitor.visitIrReturn(this);
+}
+
+class IrConstant extends IrNode {
+  final Constant value;
+
+  IrConstant(position, this.value) : super(position);
+
+  accept(IrNodesVisitor visitor) => visitor.visitIrConstant(this);
+}
+
+
+abstract class IrNodesVisitor<T> {
+  T visit(IrNode node) => node.accept(this);
+
+  void visitAll(List<IrNode> nodes) {
+    for (IrNode n in nodes) visit(n);
+  }
+
+  T visitNode(IrNode node);
+
+  T visitIrFunction(IrFunction node) => visitNode(node);
+  T visitIrReturn(IrReturn node) => visitNode(node);
+  T visitIrConstant(IrConstant node) => visitNode(node);
+}