Add support for reading .gypi files.

tools/gn/parse_tree.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/parse_tree.h"
 
 #include <string>
 
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 35 matching lines @@
 }
 
 AccessorNode::~AccessorNode() {
 }
 
 const AccessorNode* AccessorNode::AsAccessor() const {
   return this;
 }
 
 Value AccessorNode::Execute(Scope* scope, Err* err) const {
-  if (index_)
+  if (index_) {
     return ExecuteArrayAccess(scope, err);
-  else if (member_)
-    return ExecuteScopeAccess(scope, err);
+  } else if (member_) {
+    const Value* value = scope->GetValue(base_.value(), true);
+    if (!value) {
+      *err = MakeErrorDescribing("Undefined identifier.");
+      return Value();
+    }
+    if (value->type() == Value::SCOPE) {
+      return ExecuteScopeAccess(scope, err);
+    } else if (value->type() == Value::DICT) {
+      return ExecuteDictAccess(value, err);
+    } else {
+      *err = MakeErrorDescribing(
+          std::string("Type \"") + Value::DescribeType(value->type()) +
+          "\" is not usable with the '.' operator.");
+      return Value();
+    }
+  }
   NOTREACHED();
   return Value();
 }
 
 LocationRange AccessorNode::GetRange() const {
   if (index_)
     return LocationRange(base_.location(), index_->GetRange().end());
   else if (member_)
     return LocationRange(base_.location(), member_->GetRange().end());
   NOTREACHED();
@@ skipping 88 matching lines @@
   }
 
   if (!result) {
     *err = Err(member_.get(), "No value named \"" +
         member_->value().value() + "\" in scope \"" + base_.value() + "\"");
     return Value();
   }
   return *result;
 }
 
+Value AccessorNode::ExecuteDictAccess(const Value* dict, Err* err) const {
+  std::map<std::string, Value>::const_iterator found =
+      dict->dict_value().find(member_->value().value().as_string());
+  if (found == dict->dict_value().end()) {
+    *err = Err(member_.get(), "No value named \"" +
+        member_->value().value() + "\" in scope \"" + base_.value() + "\"");
+    return Value();
+  }
+  return found->second;
+}
+
 // BinaryOpNode ---------------------------------------------------------------
 
 BinaryOpNode::BinaryOpNode() {
 }
 
 BinaryOpNode::~BinaryOpNode() {
 }
 
 const BinaryOpNode* BinaryOpNode::AsBinaryOp() const {
   return this;
@@ skipping 342 matching lines @@
 
 Err UnaryOpNode::MakeErrorDescribing(const std::string& msg,
                                      const std::string& help) const {
   return Err(op_, msg, help);
 }
 
 void UnaryOpNode::Print(std::ostream& out, int indent) const {
   out << IndentFor(indent) << "UNARY(" << op_.value() << ")\n";
   operand_->Print(out, indent + 1);
 }