base/scoped_cftyperef.h

   1 // Copyright (c) 2006-2008 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_SCOPED_CFTYPEREF_H_
   6 #define BASE_SCOPED_CFTYPEREF_H_
   7
   8 #include <CoreFoundation/CoreFoundation.h>
   9 #include "base/basictypes.h"
  10 #include "base/compiler_specific.h"
  11
  12 // scoped_cftyperef<> is patterned after scoped_ptr<>, but maintains ownership
  13 // of a CoreFoundation object: any object that can be represented as a
  14 // CFTypeRef.  Style deviations here are solely for compatibility with
  15 // scoped_ptr<>'s interface, with which everyone is already familiar.
  16 //
  17 // When scoped_cftyperef<> takes ownership of an object (in the constructor or
  18 // in reset()), it takes over the caller's existing ownership claim.  The
  19 // caller must own the object it gives to scoped_cftyperef<>, and relinquishes
  20 // an ownership claim to that object.  scoped_cftyperef<> does not call
  21 // CFRetain().
  22 template<typename CFT>
  23 class scoped_cftyperef {
  24  public:
  25   typedef CFT element_type;
  26
  27   explicit scoped_cftyperef(CFT object = NULL)
  28       : object_(object) {
  29   }
  30
  31   ~scoped_cftyperef() {
  32     if (object_)
  33       CFRelease(object_);
  34   }
  35
  36   void reset(CFT object = NULL) {
  37     if (object_)
  38       CFRelease(object_);
  39     object_ = object;
  40   }
  41
  42   bool operator==(CFT that) const {
  43     return object_ == that;
  44   }
  45
  46   bool operator!=(CFT that) const {
  47     return object_ != that;
  48   }
  49
  50   operator CFT() const {
  51     return object_;
  52   }
  53
  54   CFT get() const {
  55     return object_;
  56   }
  57
  58   void swap(scoped_cftyperef& that) {
  59     CFT temp = that.object_;
  60     that.object_ = object_;
  61     object_ = temp;
  62   }
  63
  64   // scoped_cftyperef<>::release() is like scoped_ptr<>::release.  It is NOT
  65   // a wrapper for CFRelease().  To force a scoped_cftyperef<> object to call
  66   // CFRelease(), use scoped_cftyperef<>::reset().
  67   CFT release() WARN_UNUSED_RESULT {
  68     CFT temp = object_;
  69     object_ = NULL;
  70     return temp;
  71   }
  72
  73  private:
  74   CFT object_;
  75
  76   DISALLOW_COPY_AND_ASSIGN(scoped_cftyperef);
  77 };
  78
  79 #endif  // BASE_SCOPED_CFTYPEREF_H_