Base JavaScript code position computation on JavaScript tracer.

pkg/js_ast/lib/src/nodes.dart

 // Copyright (c) 2012, 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.
 
 part of js_ast;
 
 abstract class NodeVisitor<T> {
   T visitProgram(Program node);
 
   T visitBlock(Block node);
@@ skipping 177 matching lines @@
 
   // Ignore comments by default.
   T visitComment(Comment node) => null;
 
   T visitAwait(Await node) => visitExpression(node);
   T visitDartYield(DartYield node) => visitStatement(node);
 }
 
 /// This tag interface has no behaviour but must be implemented by any class
 /// that is to be stored on a [Node] as source information.
-abstract class JavaScriptNodeSourceInformation {}
+abstract class JavaScriptNodeSourceInformation {
+  const JavaScriptNodeSourceInformation();
+}
 
 abstract class Node {
   JavaScriptNodeSourceInformation get sourceInformation => _sourceInformation;
 
   JavaScriptNodeSourceInformation _sourceInformation;
 
   accept(NodeVisitor visitor);
   void visitChildren(NodeVisitor visitor);
 
   // Shallow clone of node.  Does not clone positions since the only use of this
@@ skipping 859 matching lines @@
 
   StringConcatenation _clone() => new StringConcatenation(this.parts);
 }
 
 class LiteralNumber extends Literal {
   final String value;  // Must be a valid JavaScript number literal.
 
   LiteralNumber(this.value);
 
   int get precedenceLevel => value.startsWith('-') ? UNARY : PRIMARY;
-  
+
   accept(NodeVisitor visitor) => visitor.visitLiteralNumber(this);
   LiteralNumber _clone() => new LiteralNumber(value);
 }
 
 class ArrayInitializer extends Expression {
   final List<Expression> elements;
 
   ArrayInitializer(this.elements);
 
   accept(NodeVisitor visitor) => visitor.visitArrayInitializer(this);
@@ skipping 196 matching lines @@
 class Comment extends Statement {
   final String comment;
 
   Comment(this.comment);
 
   accept(NodeVisitor visitor) => visitor.visitComment(this);
   Comment _clone() => new Comment(comment);
 
   void visitChildren(NodeVisitor visitor) {}
 }