Add "." accessors to GN.

tools/gn/scope.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "tools/gn/scope.h"
 
 #include "base/logging.h"
 #include "base/stl_util.h"
 #include "tools/gn/parse_tree.h"
 
@@ skipping 50 matching lines @@
   }
 
   // Search in the parent scope.
   if (const_containing_)
     return const_containing_->GetValue(ident);
   if (mutable_containing_)
     return mutable_containing_->GetValue(ident, counts_as_used);
   return NULL;
 }
 
+Value* Scope::GetMutableValue(const base::StringPiece& ident,
+                              bool counts_as_used) {
+  // Don't do programatic values, which are not mutable.
+  RecordMap::iterator found = values_.find(ident);
+  if (found != values_.end()) {
+    if (counts_as_used)
+      found->second.used = true;
+    return &found->second.value;
+  }
+
+  // Search in the parent mutable scope, but not const one.
+  if (mutable_containing_)
+    return mutable_containing_->GetMutableValue(ident, counts_as_used);
+  return NULL;
+}
+
 Value* Scope::GetValueForcedToCurrentScope(const base::StringPiece& ident,
                                            const ParseNode* set_node) {
   RecordMap::iterator found = values_.find(ident);
   if (found != values_.end())
     return &found->second.value;  // Already have in the current scope.
 
   // Search in the parent scope.
   if (containing()) {
     const Value* in_containing = containing()->GetValue(ident);
     if (in_containing) {
@@ skipping 270 matching lines @@
 }
 
 void Scope::AddProvider(ProgrammaticProvider* p) {
   programmatic_providers_.insert(p);
 }
 
 void Scope::RemoveProvider(ProgrammaticProvider* p) {
   DCHECK(programmatic_providers_.find(p) != programmatic_providers_.end());
   programmatic_providers_.erase(p);
 }