native_client_sdk/src/libraries/sdk_util/scoped_ref.h

   1 // Copyright 2013 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 LIBRARIES_SDK_UTIL_SCOPED_REF_H_
   6 #define LIBRARIES_SDK_UTIL_SCOPED_REF_H_
   7
   8 #include <stdlib.h>
   9
  10 #include "sdk_util/macros.h"
  11 #include "sdk_util/ref_object.h"
  12
  13 namespace sdk_util {
  14
  15 class ScopedRefBase {
  16  protected:
  17   ScopedRefBase() : ptr_(NULL) {}
  18   ~ScopedRefBase() { reset(NULL); }
  19
  20   void reset(RefObject* obj) {
  21     if (obj) {
  22       obj->Acquire();
  23     }
  24     if (ptr_) {
  25       ptr_->Release();
  26     }
  27     ptr_ = obj;
  28   }
  29
  30  protected:
  31   RefObject* ptr_;
  32 };
  33
  34 template <class T>
  35 class ScopedRef : public ScopedRefBase {
  36  public:
  37   ScopedRef() {}
  38   ScopedRef(const ScopedRef& ptr) { reset(ptr.get()); }
  39   explicit ScopedRef(T* ptr) { reset(ptr); }
  40
  41   ScopedRef& operator=(const ScopedRef& ptr) {
  42     reset(ptr.get());
  43     return *this;
  44   }
  45
  46   template <typename U>
  47   ScopedRef(const ScopedRef<U>& ptr) {
  48     reset(ptr.get());
  49   }
  50
  51   template <typename U>
  52   ScopedRef& operator=(const ScopedRef<U>& ptr) {
  53     reset(ptr.get());
  54     return *this;
  55   }
  56
  57   void reset(T* obj = NULL) { ScopedRefBase::reset(obj); }
  58   T* get() const { return static_cast<T*>(ptr_); }
  59
  60   template <typename U>
  61   bool operator==(const ScopedRef<U>& p) const {
  62     return get() == p.get();
  63   }
  64
  65   template <typename U>
  66   bool operator!=(const ScopedRef<U>& p) const {
  67     return get() != p.get();
  68   }
  69
  70  public:
  71   T& operator*() const { return *get(); }
  72   T* operator->() const { return get(); }
  73
  74  private:
  75   typedef void (ScopedRef::*bool_as_func_ptr)() const;
  76   void bool_as_func_impl() const {};
  77
  78  public:
  79   operator bool_as_func_ptr() const {
  80     return (ptr_ != NULL) ? &ScopedRef::bool_as_func_impl : 0;
  81   }
  82 };
  83
  84 template <typename U, typename T>
  85 ScopedRef<U> static_scoped_ref_cast(const ScopedRef<T>& ptr) {
  86   return ScopedRef<U>(static_cast<U*>(ptr.get()));
  87 }
  88
  89 }  // namespace sdk_util
  90
  91 #endif  // LIBRARIES_SDK_UTIL_SCOPED_REF_H_