null-aware operators in the VM

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 244 matching lines @@
 bool BinaryOpNode::IsKindValid() const {
   switch (kind_) {
     case Token::kADD:
     case Token::kSUB:
     case Token::kMUL:
     case Token::kDIV:
     case Token::kTRUNCDIV:
     case Token::kMOD:
     case Token::kOR:
     case Token::kAND:
+    case Token::kIFNULL:
     case Token::kBIT_OR:
     case Token::kBIT_XOR:
     case Token::kBIT_AND:
     case Token::kSHL:
     case Token::kSHR:
       return true;
     default:
       return false;
   }
 }
@@ skipping 247 matching lines @@
         field().token_pos(),
         rhs,
         AbstractType::ZoneHandle(field().type()),
         String::ZoneHandle(field().name()));
   }
   return new StoreStaticFieldNode(token_pos(), field(), rhs);
 }
 
 
 AstNode* InstanceGetterNode::MakeAssignmentNode(AstNode* rhs) {
-  return new InstanceSetterNode(token_pos(), receiver(), field_name(), rhs);
+  return new InstanceSetterNode(token_pos(),
+                                receiver(),
+                                field_name(),
+                                rhs,
+                                is_conditional());
 }
 
 
 bool InstanceGetterNode::IsPotentiallyConst() const {
   return field_name().Equals(Symbols::Length()) &&
+    !is_conditional() &&
     receiver()->IsPotentiallyConst();
 }
 
 
 const Instance* InstanceGetterNode::EvalConstExpr() const {
-  if (field_name().Equals(Symbols::Length())) {
+  if (field_name().Equals(Symbols::Length()) && !is_conditional()) {
     const Instance* receiver_val = receiver()->EvalConstExpr();
     if ((receiver_val != NULL) && receiver_val->IsString()) {
       return &Instance::ZoneHandle(Smi::New(1));
     }
   }
   return NULL;
 }
 
 
 AstNode* LoadIndexedNode::MakeAssignmentNode(AstNode* rhs) {
@@ skipping 189 matching lines @@
   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