Partial solution to analyze potentially constant expressions

runtime/vm/ast.h

 // 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.
 
 #ifndef VM_AST_H_
 #define VM_AST_H_
 
 #include "platform/assert.h"
 #include "vm/allocation.h"
 #include "vm/growable_array.h"
@@ skipping 110 matching lines @@
   // parsing as the assignment context was not known yet at that time.
   virtual AstNode* MakeAssignmentNode(AstNode* rhs) {
     return NULL;  // By default all nodes are not assignable.
   }
 
   // Return NULL if 'unary_op_kind' can't be applied.
   virtual AstNode* ApplyUnaryOp(Token::Kind unary_op_kind) {
     return NULL;
   }
 
+  virtual bool IsPotentiallyConst() const { return false; }
+
   // Analyzes an expression to determine whether it is a compile time
   // constant or not. Returns NULL if the expression is not a compile time
   // constant. Otherwise, the return value is an approximation of the
   // actual value of the const expression. The type of the returned value
   // corresponds to the type of the const expression and is either
   // Number, Integer, String, Bool, or anything else (not a subtype of
   // the former).
   virtual const Instance* EvalConstExpr() const { return NULL; }
 
  protected:
@@ skipping 179 matching lines @@
       ASSERT(String::Cast(literal_).IsSymbol());
     }
 #endif  // defined(DEBUG)
     ASSERT(literal_.IsNull() ||
            Class::Handle(literal_.clazz()).is_finalized() ||
            Class::Handle(literal_.clazz()).is_prefinalized());
   }
 
   const Instance& literal() const { return literal_; }
 
+  virtual bool IsPotentiallyConst() const;
   virtual const Instance* EvalConstExpr() const {
     return &literal();
   }
 
   virtual void VisitChildren(AstNodeVisitor* visitor) const { }
 
   virtual AstNode* ApplyUnaryOp(Token::Kind unary_op_kind);
 
   DECLARE_COMMON_NODE_FUNCTIONS(LiteralNode);
 
@@ skipping 89 matching lines @@
   AstNode* receiver() const { return receiver_; }
   LocalScope* scope() const { return scope_; }
 
   virtual void VisitChildren(AstNodeVisitor* visitor) const {
     if (receiver() != NULL) {
       receiver()->Visit(visitor);
     }
   }
 
   virtual AstNode* MakeAssignmentNode(AstNode* rhs);
-
+  virtual bool IsPotentiallyConst() const;
   virtual const Instance* EvalConstExpr() const;
 
   DECLARE_COMMON_NODE_FUNCTIONS(ClosureNode);
 
  private:
   const Function& function_;
   AstNode* receiver_;
   LocalScope* scope_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(ClosureNode);
@@ skipping 85 matching lines @@
   Token::Kind kind() const { return kind_; }
   AstNode* left() const { return left_; }
   AstNode* right() const { return right_; }
 
   virtual void VisitChildren(AstNodeVisitor* visitor) const {
     left()->Visit(visitor);
     right()->Visit(visitor);
   }
 
   virtual const char* Name() const;
+  virtual bool IsPotentiallyConst() const;
   virtual const Instance* EvalConstExpr() const;
 
   DECLARE_COMMON_NODE_FUNCTIONS(ComparisonNode);
 
  private:
   const Token::Kind kind_;
   AstNode* left_;
   AstNode* right_;
 
   bool IsKindValid() const;
@@ skipping 17 matching lines @@
   Token::Kind kind() const { return kind_; }
   AstNode* left() const { return left_; }
   AstNode* right() const { return right_; }
 
   virtual void VisitChildren(AstNodeVisitor* visitor) const {
     left()->Visit(visitor);
     right()->Visit(visitor);
   }
 
   virtual const char* Name() const;
+  virtual bool IsPotentiallyConst() const;
   virtual const Instance* EvalConstExpr() const;
 
   DECLARE_COMMON_NODE_FUNCTIONS(BinaryOpNode);
 
  private:
   const Token::Kind kind_;
   AstNode* left_;
   AstNode* right_;
 
   bool IsKindValid() const;
@@ skipping 17 matching lines @@
   }
 
   Token::Kind kind() const { return kind_; }
   AstNode* operand() const { return operand_; }
 
   virtual void VisitChildren(AstNodeVisitor* visitor) const {
     operand()->Visit(visitor);
   }
 
   virtual const char* Name() const;
+  virtual bool IsPotentiallyConst() const;
   virtual const Instance* EvalConstExpr() const;
 
   DECLARE_COMMON_NODE_FUNCTIONS(UnaryOpNode);
 
  private:
   const Token::Kind kind_;
   AstNode* operand_;
 
   bool IsKindValid() const;
 
@@ skipping 322 matching lines @@
   LoadLocalNode(intptr_t token_pos, const LocalVariable* local)
       : AstNode(token_pos), local_(*local) {
     ASSERT(local != NULL);
   }
 
   const LocalVariable& local() const { return local_; }
 
   virtual void VisitChildren(AstNodeVisitor* visitor) const { }
 
   virtual const Instance* EvalConstExpr() const;
+  virtual bool IsPotentiallyConst() const;
   virtual AstNode* MakeAssignmentNode(AstNode* rhs);
 
   DECLARE_COMMON_NODE_FUNCTIONS(LoadLocalNode);
 
  private:
   const LocalVariable& local_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(LoadLocalNode);
 };
 
@@ skipping 345 matching lines @@
   //    static getter, but no field and no static setter are declared.
   AstNode* receiver() const { return receiver_; }
   const Class& cls() const { return cls_; }
   const String& field_name() const { return field_name_; }
   bool is_super_getter() const { return is_super_getter_; }
 
   virtual void VisitChildren(AstNodeVisitor* visitor) const { }
 
   virtual AstNode* MakeAssignmentNode(AstNode* rhs);
 
+  virtual bool IsPotentiallyConst() const;
   virtual const Instance* EvalConstExpr() const;
 
   DECLARE_COMMON_NODE_FUNCTIONS(StaticGetterNode);
 
  private:
   AstNode* receiver_;
   const Class& cls_;
   const String& field_name_;
   const bool is_super_getter_;
 
@@ skipping 347 matching lines @@
   const LocalVariable& context_var_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(InlinedFinallyNode);
 };
 
 }  // namespace dart
 
 #undef DECLARE_COMMON_NODE_FUNCTIONS
 
 #endif  // VM_AST_H_