Support local variables in dart2dart.

sdk/lib/_internal/compiler/implementation/ir/ir_builder.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.
 
 library dart2js.ir_builder;
 
 import 'ir_nodes.dart' as ir;
 import '../elements/elements.dart';
 import '../dart2jslib.dart';
 import '../dart_types.dart';
@@ skipping 401 matching lines @@
 
   ir.Definition visitTypeReferenceSend(ast.Send node) {
     return giveup();
   }
 
   ir.Definition visitSendSet(ast.SendSet node) {
     Element element = elements[node];
     if (!Elements.isLocal(element)) return giveup();
     if (node.assignmentOperator.source != '=') return giveup();
     // Exactly one argument expected for a simple assignment.
-    assert(!node.arguments.isEmpty && node.arguments.tail.isEmpty);
+    assert(!node.arguments.isEmpty);
+    assert(node.arguments.tail.isEmpty);
     ir.Definition result = node.arguments.head.accept(this);
     assignedVars[variableIndex[element]] = result;
     return result;
   }
 
+  ir.Definition visitVariableDefinitions(ast.VariableDefinitions node) {
+    assert(isOpen);
+    for (ast.Node definition in node.definitions.nodes) {
+      Element element = elements[definition];
+      // Definitions are either SendSets if there is an initializer, or
+      // Identifiers if there is no initializer.
+      if (definition is ast.SendSet) {
+        assert(!definition.arguments.isEmpty);
+        assert(definition.arguments.tail.isEmpty);
+        ir.Definition initialValue = definition.arguments.head.accept(this);
+        if (!isOpen) return null;

[karlklose, 2014/04/11 09:01:56]

Perhaps add a comment.

[Kevin Millikin (Google), 2014/04/11 10:28:51]

I will.

+        variableIndex[element] = assignedVars.length;
+        assignedVars.add(initialValue);
+      } else {
+        assert(definition is ast.Identifier);
+        // The initial value is null.
+        // TODO(kmillikin): Consider pooling constants.
+        ir.Constant constant = new ir.Constant(constantSystem.createNull());
+        add(new ir.LetPrim(constant));
+        variableIndex[element] = assignedVars.length;
+        assignedVars.add(constant);
+      }
+    }
+    return null;
+  }
+
   static final String ABORT_IRNODE_BUILDER = "IrNode builder aborted";
 
   ir.Definition giveup() => throw ABORT_IRNODE_BUILDER;
 
   ir.FunctionDefinition nullIfGiveup(ir.FunctionDefinition action()) {
     try {
       return action();
     } catch(e) {
       if (e == ABORT_IRNODE_BUILDER) return null;
       rethrow;
     }
   }
 
   void internalError(String reason, {ast.Node node}) {
     giveup();
   }
 }
 
 // Verify that types are ones that can be reconstructed by the type emitter.
 class SupportedTypeVerifier extends DartTypeVisitor<bool, Null> {
   bool visitType(DartType type, Null _) => false;
 
   bool visitVoidType(VoidType type, Null _) => true;
 
   // Currently, InterfaceType and TypedefType are supported so long as they
   // do not have type parameters.  They are subclasses of GenericType.
   bool visitGenericType(GenericType type, Null _) => !type.isGeneric;
 }