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1// -*- Mode: C++; -*-
2/*
3 This file is part of the Opie Project
4 Copyright (C) 2004 Rajko Albrecht <alwin@handhelds.org>
5 Copyright (C) The Opie Team <opie-devel@handhelds.org>
6 =.
7 .=l.
8 .>+-=
9_;:, .> :=|. This program is free software; you can
10.> <`_, > . <= redistribute it and/or modify it under
11:`=1 )Y*s>-.-- : the terms of the GNU Library General Public
12.="- .-=="i, .._ License as published by the Free Software
13- . .-<_> .<> Foundation; either version 2 of the License,
14 ._= =} : or (at your option) any later version.
15 .%`+i> _;_.
16 .i_,=:_. -<s. This program is distributed in the hope that
17 + . -:. = it will be useful, but WITHOUT ANY WARRANTY;
18 : .. .:, . . . without even the implied warranty of
19 =_ + =;=|` MERCHANTABILITY or FITNESS FOR A
20 _.=:. : :=>`: PARTICULAR PURPOSE. See the GNU
21..}^=.= = ; Library General Public License for more
22++= -. .` .: details.
23: = ...= . :.=-
24-. .:....=;==+<; You should have received a copy of the GNU
25 -_. . . )=. = Library General Public License along with
26 -- :-=` this library; see the file COPYING.LIB.
27 If not, write to the Free Software Foundation,
28 Inc., 59 Temple Place - Suite 330,
29 Boston, MA 02111-1307, USA.
30*/
31
32#ifndef _OSmartPointer_h
33#define _OSmartPointer_h
34
35/*!
36 * \file OSmartPointer.h
37 * \brief smart pointer and reference counter
38 * \author Rajko Albrecht
39 *
40 */
41
42namespace Opie {
43
44//! simple reference counter class
45class ORefCount {
46protected:
47 //! reference count member
48 long m_RefCount;
49public:
50 //! first reference must be added after "new" via Pointer()
51 ORefCount() : m_RefCount(0)
52 {}
53 virtual ~ORefCount() {}
54 //! add a reference
55 void Incr() {
56 ++m_RefCount;
57 }
58 //! delete a reference
59 void Decr() {
60 --m_RefCount;
61 }
62 //! is it referenced
63 bool Shared() { return (m_RefCount > 0); }
64};
65
66//! reference counting wrapper class
67template<class T> class OSmartPointer {
68 //! pointer to object
69 /*!
70 * this object must contain Incr(), Decr() and Shared()
71 * methode as public members. The best way is, that it will be a child
72 * class of RefCount
73 */
74 T *ptr;
75public:
76 //! standart constructor
77 OSmartPointer() { ptr = NULL; }
78 //! standart destructor
79 /*!
80 * release the reference, if it were the last reference, destroys
81 * ptr
82 */
83 ~OSmartPointer()
84 {
85 if (ptr){
86 ptr->Decr();
87 if (!ptr->Shared())
88 delete ptr;
89 }
90 }
91 //! construction
92 OSmartPointer(T* t) { if (ptr = t) ptr->Incr(); }
93 //! Pointer copy
94 OSmartPointer(const OSmartPointer<T>& p)
95 { if (ptr = p.ptr) ptr->Incr(); }
96 //! pointer copy by assignment
97 OSmartPointer<T>& operator= (const OSmartPointer<T>& p)
98 {
99 // already same: nothing to do
100 if (ptr == p.ptr) return *this;
101 // decouple reference
102 if (ptr) { ptr->Decr(); if (!ptr->Shared()) delete ptr; }
103 // establish new reference
104 if (ptr = p.ptr) ptr->Incr();
105 return *this;
106 }
107 OSmartPointer<T>& operator= (T*p)
108 {
109 if (ptr==p)return *this;
110 if (ptr) {
111 ptr->Decr();
112 if (!ptr->Shared()) delete ptr;
113 }
114 if (ptr=p) ptr->Incr();
115 return *this;
116 }
117
118 //! cast to conventional pointer
119 operator T* () const { return ptr; }
120
121 //! deref: fails for NULL pointer
122 T& operator* () {return *ptr; }
123 //! deref: fails for NULL pointer
124 const T& operator* ()const {return *ptr; }
125
126 //! deref with method call
127 T* operator-> () {return ptr; }
128 //! deref with const method call
129 const T* operator-> ()const {return ptr; }
130
131 //! supports "if (pointer)"
132 operator bool () const { return (ptr != NULL); }
133 //! "if (pointer)" as non const
134 operator bool () { return ptr != NULL;}
135
136 //! support if (!pointer)"
137 bool operator! () const { return (ptr == NULL); }
138 //! support if (!pointer)" as non const
139 bool operator! () { return (ptr == NULL); }
140};
141
142}
143
144#endif
145