PPAPI: Reduce string copying in SerializedVar.

ppapi/shared_impl/var.h

 // Copyright (c) 2012 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 PPAPI_SHARED_IMPL_VAR_H_
 #define PPAPI_SHARED_IMPL_VAR_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
 #include "ppapi/c/pp_var.h"
 #include "ppapi/shared_impl/ppapi_shared_export.h"
 
 namespace ppapi {
 
 class ArrayBufferVar;
 class NPObjectVar;
 class ProxyObjectVar;
 class StringVar;
 class VarTracker;
@@ skipping 64 matching lines @@
 //
 // Converting a PP_Var to a string:
 //   StringVar* string = StringVar::FromPPVar(var);
 //   if (!string)
 //     return false;  // Not a string or an invalid var.
 //   DoSomethingWithTheString(string->value());
 class PPAPI_SHARED_EXPORT StringVar : public Var {
  public:
   StringVar(const std::string& str);
   StringVar(const char* str, uint32 len);
+  StringVar(scoped_ptr<std::string> str);
   virtual ~StringVar();
 
   const std::string& value() const { return value_; }
+  // Return a pointer to the internal string. This allows other objects to
+  // temporarily store a weak pointer to our internal string. Use with care; the
+  // pointer *will* become invalid if this StringVar is removed from the
+  // tracker. (All of this applies to value(), but this one's even easier to use
+  // dangerously).
+  const std::string* ptr() const { return &value_; }
 
   // Var override.
   virtual StringVar* AsStringVar() OVERRIDE;
   virtual PP_VarType GetType() const OVERRIDE;
 
   // Helper function to create a PP_Var of type string that contains a copy of
   // the given string. The input data must be valid UTF-8 encoded text, if it
   // is not valid UTF-8, a NULL var will be returned.
   //
   // The return value will have a reference count of 1. Internally, this will
   // create a StringVar and return the reference to it in the var.
   static PP_Var StringToPPVar(const std::string& str);
   static PP_Var StringToPPVar(const char* str, uint32 len);
+  static PP_Var StringToPPVar(scoped_ptr<std::string> str);
 
   // Helper function that converts a PP_Var to a string. This will return NULL
   // if the PP_Var is not of string type or the string is invalid.
   static StringVar* FromPPVar(PP_Var var);
 
  private:
   std::string value_;
 
   DISALLOW_COPY_AND_ASSIGN(StringVar);
 };
@@ skipping 29 matching lines @@
   // return NULL if the PP_Var is not of ArrayBuffer type.
   static ArrayBufferVar* FromPPVar(PP_Var var);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ArrayBufferVar);
 };
 
 }  // namespace ppapi
 
 #endif  // PPAPI_SHARED_IMPL_VAR_H_