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