base/win/scoped_co_mem.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_WIN_SCOPED_CO_MEM_H_
   6 #define BASE_WIN_SCOPED_CO_MEM_H_
   7
   8 #include <objbase.h>
   9
  10 #include "base/basictypes.h"
  11 #include "base/logging.h"
  12
  13 namespace base {
  14 namespace win {
  15
  16 // Simple scoped memory releaser class for COM allocated memory.
  17 // Example:
  18 //   base::win::ScopedCoMem<ITEMIDLIST> file_item;
  19 //   SHGetSomeInfo(&file_item, ...);
  20 //   ...
  21 //   return;  <-- memory released
  22 template<typename T>
  23 class ScopedCoMem {
  24  public:
  25   ScopedCoMem() : mem_ptr_(NULL) {}
  26   ~ScopedCoMem() {
  27     Reset(NULL);
  28   }
  29
  30   T** operator&() {  // NOLINT
  31     DCHECK(mem_ptr_ == NULL);  // To catch memory leaks.
  32     return &mem_ptr_;
  33   }
  34
  35   operator T*() {
  36     return mem_ptr_;
  37   }
  38
  39   T* operator->() {
  40     DCHECK(mem_ptr_ != NULL);
  41     return mem_ptr_;
  42   }
  43
  44   const T* operator->() const {
  45     DCHECK(mem_ptr_ != NULL);
  46     return mem_ptr_;
  47   }
  48
  49   void Reset(T* ptr) {
  50     if (mem_ptr_)
  51       CoTaskMemFree(mem_ptr_);
  52     mem_ptr_ = ptr;
  53   }
  54
  55   T* get() const {
  56     return mem_ptr_;
  57   }
  58
  59  private:
  60   T* mem_ptr_;
  61
  62   DISALLOW_COPY_AND_ASSIGN(ScopedCoMem);
  63 };
  64
  65 }  // namespace win
  66 }  // namespace base
  67
  68 #endif  // BASE_WIN_SCOPED_CO_MEM_H_