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