Add a "Label" Node around an Identifier that is being used as a label.

lib/compiler/implementation/resolver.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.
 
 interface TreeElements {
   Element operator[](Node node);
   Selector getSelector(Send send);
   Type getType(TypeAnnotation annotation);
 }
 
@@ skipping 120 matching lines @@
       if (isConstructor) {
         // Even if there is no initializer list we still have to do the
         // resolution in case there is an implicit super constructor call.
         InitializerResolver resolver = new InitializerResolver(visitor);
         FunctionElement redirection =
             resolver.resolveInitializers(element, tree);
         if (redirection !== null) {
           resolveRedirectingConstructor(resolver, tree, element, redirection);
         }
       } else if (tree.initializers != null) {
-        error(tree, MessageKind.FUNCTION_WITH_INITIALIZER);        
+        error(tree, MessageKind.FUNCTION_WITH_INITIALIZER);
       }
       visitor.visit(tree.body);
 
       // Resolve the type annotations encountered in the method.
       while (!toResolve.isEmpty()) {
         ClassElement classElement = toResolve.removeFirst();
         classElement.ensureResolved(compiler);
       }
       if (isConstructor) {
         constructorElements[element] = visitor.mapping;
@@ skipping 243 matching lines @@
     for (Link<Node> link = initializers;
          !link.isEmpty();
          link = link.tail) {
       if (link.head.asSendSet() != null) {
         final SendSet init = link.head.asSendSet();
         resolveFieldInitializer(constructor, init);
       } else if (link.head.asSend() !== null) {
         final Send call = link.head.asSend();
         if (Initializers.isSuperConstructorCall(call)) {
           if (resolvedSuper) {
-            error(call, MessageKind.DUPLICATE_SUPER_INITIALIZER);          
+            error(call, MessageKind.DUPLICATE_SUPER_INITIALIZER);
           }
           resolveSuperOrThisForSend(constructor, functionNode, call);
           resolvedSuper = true;
         } else if (Initializers.isConstructorRedirect(call)) {
           // Check that there is no body (Language specification 7.5.1).
           if (functionNode.hasBody()) {
             error(functionNode, MessageKind.REDIRECTING_CONSTRUCTOR_HAS_BODY);
           }
           // Check that there are no other initializers.
           if (!initializers.tail.isEmpty()) {
@@ skipping 815 matching lines @@
         && (declaration is !VariableDefinitions ||
         !declaration.asVariableDefinitions().definitions.nodes.tail.isEmpty()))
     {
       // The variable declaration is either not an identifier, not a
       // declaration, or it's declaring more than one variable.
       error(node.declaredIdentifier, MessageKind.INVALID_FOR_IN, []);
     }
   }
 
   visitLabeledStatement(LabeledStatement node) {
-    String labelName = node.label.source.slowToString();
+    String labelName = node.label.slowToString();
     LabelElement existingElement = statementScope.lookupLabel(labelName);
     if (existingElement !== null) {
       warning(node.label, MessageKind.DUPLICATE_LABEL, [labelName]);
       warning(existingElement.label, MessageKind.EXISTING_LABEL, [labelName]);
     }
     Node body = node.getBody();
     TargetElement targetElement = getOrCreateTargetElement(body);
 
     LabelElement element = targetElement.addLabel(node.label, labelName);
     statementScope.enterLabelScope(element);
@@ skipping 25 matching lines @@
 
   visitSwitchStatement(SwitchStatement node) {
     node.expression.accept(this);
 
     TargetElement breakElement = getOrCreateTargetElement(node);
     Map<String, LabelElement> continueLabels = <LabelElement>{};
     Link<Node> cases = node.cases.nodes;
     while (!cases.isEmpty()) {
       SwitchCase switchCase = cases.head;
       if (switchCase.label !== null) {
-        Identifier labelIdentifier = switchCase.label;
-        String labelName = labelIdentifier.source.slowToString();
+        Label label = switchCase.label;
+        String labelName = label.slowToString();
 
         LabelElement existingElement = continueLabels[labelName];
         if (existingElement !== null) {
           // It's an error if the same label occurs twice in the same switch.
-          warning(labelIdentifier, MessageKind.DUPLICATE_LABEL, [labelName]);
+          warning(label, MessageKind.DUPLICATE_LABEL, [labelName]);
           error(existingElement.label, MessageKind.EXISTING_LABEL, [labelName]);
         } else {
           // It's only a warning if it shadows another label.
           existingElement = statementScope.lookupLabel(labelName);
           if (existingElement !== null) {
-            warning(labelIdentifier, MessageKind.DUPLICATE_LABEL, [labelName]);
+            warning(label, MessageKind.DUPLICATE_LABEL, [labelName]);
             warning(existingElement.label,
                     MessageKind.EXISTING_LABEL, [labelName]);
           }
         }
 
         TargetElement targetElement =
             new TargetElement(switchCase,
                               statementScope.nestingLevel,
                               enclosingElement);
         mapping[switchCase] = targetElement;
 
-        LabelElement label =
-            new LabelElement(labelIdentifier, labelName,
+        LabelElement labelElement =
+            new LabelElement(label, labelName,
                              targetElement, enclosingElement);
-        mapping[labelIdentifier] = label;
-        continueLabels[labelName] = label;
+        mapping[label] = labelElement;
+        continueLabels[labelName] = labelElement;
       }
       cases = cases.tail;
       if (switchCase.defaultKeyword !== null && !cases.isEmpty()) {
         error(switchCase, MessageKind.INVALID_CASE_DEFAULT);
       }
     }
     statementScope.enterSwitch(breakElement, continueLabels);
     node.cases.accept(this);
     statementScope.exitSwitch();
 
@@ skipping 600 matching lines @@
 
   TopScope(LibraryElement library) : super(null, library);
   Element lookup(SourceString name) {
     return library.find(name);
   }
 
   Element add(Element newElement) {
     throw "Cannot add an element in the top scope";
   }
 }