Use ConstExp for storing constants.

sdk/lib/_internal/compiler/implementation/constants.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 dart2js;
 
 abstract class ConstantVisitor<R> {
   const ConstantVisitor();
 
   R visitFunction(FunctionConstant constant);
   R visitNull(NullConstant constant);
   R visitInt(IntConstant constant);
   R visitDouble(DoubleConstant constant);
   R visitTrue(TrueConstant constant);
   R visitFalse(FalseConstant constant);
   R visitString(StringConstant constant);
   R visitList(ListConstant constant);
   R visitMap(MapConstant constant);
   R visitConstructed(ConstructedConstant constant);
   R visitType(TypeConstant constant);
   R visitInterceptor(InterceptorConstant constant);
   R visitDummy(DummyConstant constant);
   R visitDeferred(DeferredConstant constant);
 }
 
 abstract class Constant {

[sigurdm, 2014/09/17 10:29:40]

We might consider renaming this `ConstantValue` though it is maybe too verbose.
`Constant` in itself does not say much.

[Johnni Winther, 2014/09/17 12:20:39]

Added a TODO.

   const Constant();
 
   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;
@@ skipping 61 matching lines @@
 
   bool operator ==(var other) {
     if (other is !PrimitiveConstant) return false;
     PrimitiveConstant otherPrimitive = other;
     // We use == instead of 'identical' so that DartStrings compare correctly.
     return value == otherPrimitive.value;
   }
 
   int get hashCode => throw new UnsupportedError('PrimitiveConstant.hashCode');
 
-  String toString() => value.toString();
+  String toString() => toSyntax();
   // Primitive constants don't have dependencies.
   List<Constant> getDependencies() => const <Constant>[];
   DartString toDartString();
+
+  /// This value in Dart syntax.
+  // TODO(johnniwinther): Move this to [Constant].
+  String toSyntax() => value.toString();

[sigurdm, 2014/09/17 10:29:41]

maybe call it `unparse` or something similar. `toSyntax` indicates we have a
type `Syntax`.

[Johnni Winther, 2014/09/17 12:20:39]

Done.

 }
 
 class NullConstant extends PrimitiveConstant {
   /** The value a Dart null is compiled to in JavaScript. */
   static const String JsNull = "null";
 
   factory NullConstant() => const NullConstant._internal();
   const NullConstant._internal();
   bool get isNull => true;
   get value => null;
@@ skipping 212 matching lines @@
     if (other is !StringConstant) return false;
     StringConstant otherString = other;
     return (hashCode == otherString.hashCode) && (value == otherString.value);
   }
 
   DartString toDartString() => value;
   int get length => value.length;
 
   accept(ConstantVisitor visitor) => visitor.visitString(this);
 
+  // TODO(johnniwinther): Ensure correct escaping.
+  String toSyntax() => '"${value.slowToString()}"';
+
   String toString() {
-    return 'StringConstant("${value.slowToString()}")';
+    return 'StringConstant(${toSyntax()})';
   }
 }
 
 abstract class ObjectConstant extends Constant {
   final DartType type;
 
   ObjectConstant(this.type);
 
   bool get isObject => true;
 
@@ skipping 206 matching lines @@
 
   String toString() {
     return 'DummyConstant($typeMask)';
   }
 }
 
 class ConstructedConstant extends ObjectConstant {
   final List<Constant> fields;
   final int hashCode;
 
-  ConstructedConstant(DartType type, List<Constant> fields,
-      {this.isLiteralSymbol: false})
+  ConstructedConstant(DartType type, List<Constant> fields)
     : this.fields = fields,
       hashCode = computeHash(type, fields),
       super(type) {
     assert(type != null);
   }
+
   bool get isConstructedObject => true;
 
-  /// True if this constant is constructed as a literal symbol.
-  final bool isLiteralSymbol;
-
   static int computeHash(DartType type, List<Constant> fields) {
     // TODO(floitsch): create a better hash.
     int hash = 0;
     for (Constant field in fields) {
       hash ^= field.hashCode;
     }
     hash ^= type.hashCode;
     return hash;
   }
 
@@ skipping 74 matching lines @@
   DartType computeType(Compiler compiler) => referenced.computeType(compiler);
 
   ti.TypeMask computeMask(Compiler compiler) {
     return referenced.computeMask(compiler);
   }
 
   String toString() {
     return 'DeferredConstant($referenced)';
   }
 }