Add ConstantExpression.evaluate.

pkg/compiler/lib/src/constants/values.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.
 
 library dart2js.constants.values;
 
 import '../core_types.dart';
 import '../dart_types.dart';
 import '../dart2jslib.dart'
     show assertDebugMode;
@@ skipping 21 matching lines @@
   R visitConstructed(ConstructedConstantValue constant, A arg);
   R visitType(TypeConstantValue constant, A arg);
   R visitInterceptor(InterceptorConstantValue constant, A arg);
   R visitDummy(DummyConstantValue constant, A arg);
   R visitDeferred(DeferredConstantValue constant, A arg);
 }
 
 abstract class ConstantValue {
   const ConstantValue();
 
+  /// `true` if this is a valid constant value.
+  bool get isConstant => true;
+
   bool get isNull => false;
   bool get isBool => false;
   bool get isTrue => false;
   bool get isFalse => false;
   bool get isInt => false;
   bool get isDouble => false;
   bool get isNum => false;
   bool get isString => false;
   bool get isList => false;
   bool get isMap => false;
@@ skipping 423 matching lines @@
     for (int i = 0 ; i < length ; i++) {
       if (i > 0) sb.write(',');
       sb.write(entries[i].unparse());
     }
     sb.write(']');
     return sb.toString();
   }
 
   String toStructuredString() {
     StringBuffer sb = new StringBuffer();
-    sb.write('ListConstant([');
+    sb.write('ListConstant(');
+    _unparseTypeArguments(sb);
+    sb.write('[');
     for (int i = 0 ; i < length ; i++) {
       if (i > 0) sb.write(',');
       sb.write(entries[i].toStructuredString());
     }
     sb.write('])');
     return sb.toString();
   }
 }
 
 class MapConstantValue extends ObjectConstantValue {
@@ skipping 48 matching lines @@
       sb.write(keys[i].unparse());
       sb.write(':');
       sb.write(values[i].unparse());
     }
     sb.write('}');
     return sb.toString();
   }
 
   String toStructuredString() {
     StringBuffer sb = new StringBuffer();
-    sb.write('MapConstant({');
+    sb.write('MapConstant(');
+    _unparseTypeArguments(sb);
+    sb.write('{');
     for (int i = 0; i < length; i++) {
       if (i > 0) sb.write(',');
       sb.write(keys[i].toStructuredString());
       sb.write(':');
       sb.write(values[i].toStructuredString());
     }
     sb.write('})');
     return sb.toString();
   }
 }
@@ skipping 145 matching lines @@
   List<ConstantValue> getDependencies() => <ConstantValue>[referenced];
 
   accept(ConstantValueVisitor visitor, arg) => visitor.visitDeferred(this, arg);
 
   DartType getType(CoreTypes types) => referenced.getType(types);
 
   String unparse() => 'deferred(${referenced.unparse()})';
 
   String toStructuredString() => 'DeferredConstant($referenced)';
 }
+
+/// A constant value resulting from a non constant or erroneous constant
+/// expression.
+// TODO(johnniwinther): Expand this to contain the error kind.
+class NonConstantValue extends ConstantValue {
+  bool get isConstant => false;
+
+  @override
+  accept(ConstantValueVisitor visitor, arg) {
+    // TODO(johnniwinther): Should this be part of the visiting?
+  }
+
+  @override
+  List<ConstantValue> getDependencies() => const <ConstantValue>[];
+
+  @override
+  DartType getType(CoreTypes types) => const DynamicType();
+
+  @override
+  String toStructuredString() => 'NonConstant';
+
+  @override
+  String unparse() => '>>non-constant<<';
+}