101 lines
2.5 KiB
C++
101 lines
2.5 KiB
C++
/** \file
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* Implements a class that maintains a reference count.
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*/
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/*
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* Copyright © 2000, 2001 Sofus Mortensen, Paul Hollingsworth
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*
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* This material is provided "as is", with absolutely no warranty
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* expressed or implied. Any use is at your own risk. Permission to
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* use or copy this software for any purpose is hereby granted without
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* fee, provided the above notices are retained on all copies.
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* Permission to modify the code and to distribute modified code is
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* granted, provided the above notices are retained, and a notice that
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* the code was modified is included with the above copyright notice.
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*
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* This header is part of Comet version 2.
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* https://github.com/alamaison/comet
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*/
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#ifndef COMET_REFERENCE_COUNT_H
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#define COMET_REFERENCE_COUNT_H
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#include <comet/config.h>
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#include <algorithm>
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namespace comet {
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/*! \addtogroup Misc
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*/
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//@{
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/// Simple reference counter.
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class reference_count
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{
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public:
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reference_count() : rc_(0) {};
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explicit reference_count(size_t x) : rc_(reinterpret_cast<size_t*>(x)) {};
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reference_count(const reference_count& x) : rc_(x.rc_) {};
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enum { FLAGVALUE = 1 };
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bool is_flag() const {
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return reinterpret_cast<size_t>(rc_) == 1;
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}
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// is_null
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/** Implies that the there are currently no outstanding references
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* to this object.
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*/
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bool is_null() const {
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return rc_ == 0;
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}
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/// Increment count.
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size_t operator++() {
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if (!rc_) {
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rc_ = new size_t(1);
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}
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return ++*rc_;
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}
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/// Decrement count.
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size_t operator--() {
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if (rc_) {
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if (--*rc_ == 0) {
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delete rc_;
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rc_ = 0;
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return 0;
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}
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return *rc_;
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}
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return 0;
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}
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void clear() {
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rc_ = 0;
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}
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void swap(reference_count &rhs) throw() {
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std::swap(rc_, rhs.rc_);
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}
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reference_count& operator=(reference_count& x)
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{
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rc_ = x.rc_;
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return *this;
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}
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private:
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size_t* rc_;
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}; // class reference_count
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//@}
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} // namespace comet
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namespace std {
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//! Specialisation of std::swap for reference_count.
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template<> inline void swap(comet::reference_count &lhs, comet::reference_count &rhs) COMET_STD_SWAP_NOTHROW
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{
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lhs.swap(rhs);
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}
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}
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#endif
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