Partial solution to analyze potentially constant expressions

runtime/vm/ast.cc

 // Copyright (c) 2011, 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.
 
 #include "vm/ast.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
 #include "vm/isolate.h"
 #include "vm/object_store.h"
 #include "vm/resolver.h"
@@ skipping 92 matching lines @@
 }
 
 
 void ArrayNode::VisitChildren(AstNodeVisitor* visitor) const {
   for (intptr_t i = 0; i < this->length(); i++) {
     ElementAt(i)->Visit(visitor);
   }
 }
 
 
+bool LiteralNode::IsPotentiallyConst() const {
+  return true;
+}
+
+
 // TODO(srdjan): Add code for logical negation.
 AstNode* LiteralNode::ApplyUnaryOp(Token::Kind unary_op_kind) {
   if (unary_op_kind == Token::kNEGATE) {
     if (literal().IsSmi()) {
       const Smi& smi = Smi::Cast(literal());
       const Instance& literal =
           Instance::ZoneHandle(Integer::New(-smi.Value()));
       return new LiteralNode(this->token_pos(), literal);
     }
     if (literal().IsDouble()) {
@@ skipping 15 matching lines @@
       || Token::IsTypeTestOperator(kind_)
       || Token::IsTypeCastOperator(kind_);
 }
 
 
 const char* ComparisonNode::Name() const {
   return Token::Str(kind_);
 }
 
 
+bool ComparisonNode::IsPotentiallyConst() const {
+  switch (kind_) {
+    case Token::kLT:
+    case Token::kGT:
+    case Token::kLTE:
+    case Token::kGTE:
+    case Token::kEQ:
+    case Token::kNE:
+    case Token::kEQ_STRICT:
+    case Token::kNE_STRICT:
+      return this->left()->IsPotentiallyConst() &&
+          this->right()->IsPotentiallyConst();
+    default:
+      return false;
+  }
+}
+
+
 const Instance* ComparisonNode::EvalConstExpr() const {
   const Instance* left_val = this->left()->EvalConstExpr();
   if (left_val == NULL) {
     return NULL;
   }
   const Instance* right_val = this->right()->EvalConstExpr();
   if (right_val == NULL) {
     return NULL;
   }
   switch (kind_) {
@@ skipping 51 matching lines @@
       return false;
   }
 }
 
 
 const char* BinaryOpNode::Name() const {
   return Token::Str(kind_);
 }
 
 
+bool BinaryOpNode::IsPotentiallyConst() const {
+  switch (kind_) {
+    case Token::kADD:
+    case Token::kSUB:
+    case Token::kMUL:
+    case Token::kDIV:
+    case Token::kMOD:
+    case Token::kTRUNCDIV:
+    case Token::kBIT_OR:
+    case Token::kBIT_XOR:
+    case Token::kBIT_AND:
+    case Token::kSHL:
+    case Token::kSHR:
+    case Token::kOR:
+    case Token::kAND:
+      return this->left()->IsPotentiallyConst() &&
+          this->right()->IsPotentiallyConst();
+    default:
+      UNREACHABLE();
+      return false;
+  }
+}
+
+
 const Instance* BinaryOpNode::EvalConstExpr() const {
   const Instance* left_val = this->left()->EvalConstExpr();
   if (left_val == NULL) {
     return NULL;
   }
   if (!left_val->IsNumber() && !left_val->IsBool()) {
     return NULL;
   }
   const Instance* right_val = this->right()->EvalConstExpr();
   if (right_val == NULL) {
@@ skipping 47 matching lines @@
   AstNode* new_operand = operand->ApplyUnaryOp(kind);
   if (new_operand != NULL) {
     return new_operand;
   }
   return new UnaryOpNode(token_pos, kind, operand);
 }
 
 
 bool UnaryOpNode::IsKindValid() const {
   switch (kind_) {
-    case Token::kADD:
     case Token::kNEGATE:
     case Token::kNOT:
     case Token::kBIT_NOT:
       return true;
     default:
       return false;
   }
 }
 
 
+bool UnaryOpNode::IsPotentiallyConst() const {
+  return this->operand()->IsPotentiallyConst();
+}
+
+
 const Instance* UnaryOpNode::EvalConstExpr() const {
   const Instance* val = this->operand()->EvalConstExpr();
   if (val == NULL) {
     return NULL;
   }
   switch (kind_) {
-    case Token::kADD:
     case Token::kNEGATE:
       return val->IsNumber() ? val : NULL;
     case Token::kNOT:
       return val->IsBool() ? val : NULL;
     case Token::kBIT_NOT:
       return val->IsInteger() ? val : NULL;
     default:
       return NULL;
   }
 }
 
 
+bool ClosureNode::IsPotentiallyConst() const {
+  if (function().IsImplicitStaticClosureFunction()) {
+    return true;
+  }
+  return false;
+}
+
+
 const Instance* ClosureNode::EvalConstExpr() const {
   if (function().IsImplicitStaticClosureFunction()) {
     // Return a value that represents an instance. Only the type is relevant.
     return &Instance::Handle();
   }
   return NULL;
 }
 
 
 AstNode* ClosureNode::MakeAssignmentNode(AstNode* rhs) {
@@ skipping 14 matching lines @@
 const char* UnaryOpNode::Name() const {
   return Token::Str(kind_);
 }
 
 
 const char* JumpNode::Name() const {
   return Token::Str(kind_);
 }
 
 
+bool LoadLocalNode::IsPotentiallyConst() const {
+  // Parameters of const constructors are implicitly final and can be
+  // used in initializer expressions.
+  // We can't check here whether the local variable is indeed a parameter,
+  // but this code is executed before any other local variables are
+  // added to the scope.
+  return local().is_final();
+}
+
+
 const Instance* LoadLocalNode::EvalConstExpr() const {
   if (local().IsConst()) {
     return local().ConstValue();
   }
   return NULL;
 }
 
 
 AstNode* LoadLocalNode::MakeAssignmentNode(AstNode* rhs) {
   if (local().is_final()) {
@@ skipping 80 matching lines @@
   const String& cls_name = String::Handle(cls.Name());
   const String& func_name = String::Handle(function().name());
   if (cls_name.Equals(Symbols::NoSuchMethodError()) &&
       func_name.StartsWith(Symbols::ThrowNew())) {
     return this;
   }
   return NULL;
 }
 
 
+bool StaticGetterNode::IsPotentiallyConst() const {
+  const String& getter_name =
+      String::Handle(Field::GetterName(this->field_name()));
+  const Function& getter_func =
+      Function::Handle(this->cls().LookupStaticFunction(getter_name));
+  if (getter_func.IsNull() || !getter_func.is_const()) {
+    return false;
+  }
+  return true;
+}
+
+
 const Instance* StaticGetterNode::EvalConstExpr() const {
   const String& getter_name =
       String::Handle(Field::GetterName(this->field_name()));
   const Function& getter_func =
       Function::Handle(this->cls().LookupStaticFunction(getter_name));
   if (getter_func.IsNull() || !getter_func.is_const()) {
     return NULL;
   }
   const Object& result = Object::Handle(
       DartEntry::InvokeFunction(getter_func, Object::empty_array()));
   if (result.IsError() || result.IsNull()) {
     // TODO(turnidge): We could get better error messages by returning
     // the Error object directly to the parser.  This will involve
     // replumbing all of the EvalConstExpr methods.
     return NULL;
   }
   return &Instance::ZoneHandle(Instance::Cast(result).raw());
 }
 
 }  // namespace dart