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// RefCount.hh for FbTk - Fluxbox Toolkit
// Copyright (c) 2002 Henrik Kinnunen (fluxgen at fluxbox dot org)
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
#ifndef FBTK_REFCOUNT_HH
#define FBTK_REFCOUNT_HH
namespace FbTk {
/// holds a pointer with reference counting, similar to std:auto_ptr
template <typename Pointer>
class RefCount {
typedef Pointer* RefCount::*bool_type;
public:
RefCount();
explicit RefCount(Pointer *p);
RefCount(const RefCount<Pointer> ©);
template<typename Pointer2>
RefCount(const RefCount<Pointer2> ©);
~RefCount();
RefCount<Pointer> &operator = (const RefCount<Pointer> ©);
RefCount<Pointer> &operator = (Pointer *p);
Pointer &operator * () const { return *get(); }
Pointer *operator -> () const { return get(); }
Pointer *get() const { return m_data; }
/// conversion to "bool"
operator bool_type() const { return m_data ? &RefCount::m_data : 0; }
private:
/// increase reference count
void incRefCount();
/// decrease reference count
void decRefCount();
Pointer *m_data; ///< data holder
unsigned int *m_refcount; ///< holds reference counting
// we need this for the template copy constructor
template<typename Pointer2>
friend class RefCount;
};
// implementation
template <typename Pointer>
RefCount<Pointer>::RefCount():m_data(0), m_refcount(new unsigned int(0)) {
incRefCount(); // it really counts how many things are storing m_refcount
}
template <typename Pointer>
template <typename Pointer2>
RefCount<Pointer>::RefCount(const RefCount<Pointer2> ©):
m_data(copy.m_data),
m_refcount(copy.m_refcount) {
incRefCount();
}
template <typename Pointer>
RefCount<Pointer>::RefCount(Pointer *p):m_data(p), m_refcount(new unsigned int(0)) {
incRefCount();
}
template <typename Pointer>
RefCount<Pointer>::RefCount(const RefCount<Pointer> ©):
m_data(copy.m_data),
m_refcount(copy.m_refcount) {
incRefCount();
}
template <typename Pointer>
RefCount<Pointer>::~RefCount() {
decRefCount();
}
template <typename Pointer>
RefCount<Pointer> &RefCount<Pointer>::operator = (const RefCount<Pointer> ©) {
decRefCount(); // dec current ref count
m_refcount = copy.m_refcount; // set new ref count
m_data = copy.m_data; // set new data pointer
incRefCount(); // inc new ref count
return *this;
}
template <typename Pointer>
RefCount<Pointer> &RefCount<Pointer>::operator = (Pointer *p) {
decRefCount();
m_data = p; // set data pointer
m_refcount = new unsigned int(0); // create new counter
incRefCount();
return *this;
}
template <typename Pointer>
void RefCount<Pointer>::decRefCount() {
if (m_refcount == 0)
return;
if (*m_refcount == 0) { // already zero, then delete refcount
delete m_refcount;
m_refcount = 0;
return;
}
(*m_refcount)--;
if (*m_refcount == 0) { // destroy m_data and m_refcount if nobody else is using this
if (m_data != 0)
delete m_data;
m_data = 0;
delete m_refcount;
m_refcount = 0;
}
}
template <typename Pointer>
void RefCount<Pointer>::incRefCount() {
if (m_refcount == 0)
return;
(*m_refcount)++;
}
} // end namespace FbTk
#endif // FBTK_REFCOUNT_HH
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