Add support for reading .gypi files.

tools/gn/value.h

 // 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.
 
 #ifndef TOOLS_GN_VALUE_H_
 #define TOOLS_GN_VALUE_H_
 
+#include <map>
+
 #include "base/basictypes.h"
 #include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/strings/string_piece.h"
 #include "tools/gn/err.h"
 
 class ParseNode;
 class Scope;
 
 // Represents a variable value in the interpreter.
 class Value {
  public:
   enum Type {
     NONE = 0,
     BOOLEAN,
     INTEGER,
     STRING,
     LIST,
-    SCOPE
+    SCOPE,
   };
 
   Value();
   Value(const ParseNode* origin, Type t);
   Value(const ParseNode* origin, bool bool_val);
   Value(const ParseNode* origin, int64 int_val);
   Value(const ParseNode* origin, std::string str_val);
   Value(const ParseNode* origin, const char* str_val);
-  Value(const ParseNode* origin, Scope* scope);  // Non-owning ptr.
-                                                 // (must outlive Value.)
+  // Values "shouldn't" have null scopes when type == Scope, so be sure to
+  // always set one. However, this is not asserted since there are some
+  // use-cases for creating values and immediately setting the scope on it. So
+  // you can pass a null scope here if you promise to set it before any other
+  // code gets it (code will generally assume the scope is not null).
+  Value(const ParseNode* origin, scoped_ptr<Scope> scope);
+
+  Value(const Value& other);
   ~Value();
 
+  Value& operator=(const Value& other);
+
   Type type() const { return type_; }
 
   // Returns a string describing the given type.
   static const char* DescribeType(Type t);
 
   // Returns the node that made this. May be NULL.
   const ParseNode* origin() const { return origin_; }
   void set_origin(const ParseNode* o) { origin_ = o; }
 
   // Sets the origin of this value, recursively going into list child
@@ skipping 31 matching lines @@
     DCHECK(type_ == LIST);
     return list_value_;
   }
   const std::vector<Value>& list_value() const {
     DCHECK(type_ == LIST);
     return list_value_;
   }
 
   Scope* scope_value() {
     DCHECK(type_ == SCOPE);
-    return scope_value_;
+    return scope_value_.get();
   }
   const Scope* scope_value() const {
     DCHECK(type_ == SCOPE);
-    return scope_value_;
+    return scope_value_.get();
   }
+  void SetScopeValue(scoped_ptr<Scope> scope);
 
   // Converts the given value to a string. Returns true if strings should be
   // quoted or the ToString of a string should be the string itself.
   std::string ToString(bool quote_strings) const;
 
   // Verifies that the value is of the given type. If it isn't, returns
   // false and sets the error.
   bool VerifyTypeIs(Type t, Err* err) const;
 
   // Compares values. Only the "value" is compared, not the origin.
   bool operator==(const Value& other) const;
   bool operator!=(const Value& other) const;
 
  private:
+  // This are a lot of objects associated with every Value that need
+  // initialization and tear down every time. It might be more efficient to
+  // create a union of ManualConstructor objects (see SmallMap) and only
+  // use the one we care about.
   Type type_;
   std::string string_value_;
   bool boolean_value_;
   int64 int_value_;
   std::vector<Value> list_value_;
-  Scope* scope_value_;  // Non-owning.
+  scoped_ptr<Scope> scope_value_;
 
   const ParseNode* origin_;
 };
 
 #endif  // TOOLS_GN_VALUE_H_