base/mac/scoped_cftyperef.h

   1 // Copyright (c) 2012 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_MAC_SCOPED_CFTYPEREF_H_
   6 #define BASE_MAC_SCOPED_CFTYPEREF_H_
   7
   8 #include <CoreFoundation/CoreFoundation.h>
   9
  10 #include "base/mac/scoped_typeref.h"
  11
  12 namespace base {
  13
  14 // ScopedCFTypeRef<> is patterned after scoped_ptr<>, but maintains ownership
  15 // of a CoreFoundation object: any object that can be represented as a
  16 // CFTypeRef.  Style deviations here are solely for compatibility with
  17 // scoped_ptr<>'s interface, with which everyone is already familiar.
  18 //
  19 // By default, ScopedCFTypeRef<> takes ownership of an object (in the
  20 // constructor or in reset()) by taking over the caller's existing ownership
  21 // claim.  The caller must own the object it gives to ScopedCFTypeRef<>, and
  22 // relinquishes an ownership claim to that object.  ScopedCFTypeRef<> does not
  23 // call CFRetain(). This behavior is parameterized by the |OwnershipPolicy|
  24 // enum. If the value |RETAIN| is passed (in the constructor or in reset()),
  25 // then ScopedCFTypeRef<> will call CFRetain() on the object, and the initial
  26 // ownership is not changed.
  27
  28 namespace internal {
  29
  30 struct ScopedCFTypeRefTraits {
  31   static void Retain(CFTypeRef object) {
  32     CFRetain(object);
  33   }
  34   static void Release(CFTypeRef object) {
  35     CFRelease(object);
  36   }
  37 };
  38
  39 }  // namespace internal
  40
  41 template<typename CFT>
  42 class ScopedCFTypeRef
  43     : public ScopedTypeRef<CFT, internal::ScopedCFTypeRefTraits> {
  44  public:
  45   typedef CFT element_type;
  46
  47   explicit ScopedCFTypeRef(
  48       CFT object = NULL,
  49       base::scoped_policy::OwnershipPolicy policy = base::scoped_policy::ASSUME)
  50       : ScopedTypeRef<CFT,
  51                       internal::ScopedCFTypeRefTraits>(object, policy) {}
  52
  53   ScopedCFTypeRef(const ScopedCFTypeRef<CFT>& that)
  54       : ScopedTypeRef<CFT, internal::ScopedCFTypeRefTraits>(that) {}
  55 };
  56
  57 }  // namespace base
  58
  59 #endif  // BASE_MAC_SCOPED_CFTYPEREF_H_