81 lines
1.6 KiB
C++
81 lines
1.6 KiB
C++
//
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// Intrusive reference counting smart pointer
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//
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// Copyright (C) 2016-2018 Andreas Gustafsson. This file is part of
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// the Gaborator library source distribution. See the file LICENSE at
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// the top level of the distribution for license information.
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//
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#ifndef _GABORATOR_REF_H
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#define _GABORATOR_REF_H
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namespace gaborator {
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template <class T> struct ref;
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struct refcounted {
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refcounted() { refcount = 0; }
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unsigned int refcount;
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};
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// Template functions for manual reference counting, without using the
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// ref<> class. It would be tempting to make these methods of struct
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// refcounted, but that won't work because it would lose the full
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// object type and invoke operator delete on the base class.
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template <class T>
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void incref(T &r) {
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r.refcount++;
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}
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template <class T>
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void decref(T &r) {
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r.refcount--;
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if (r.refcount == 0)
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delete &r;
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}
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template <class T>
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struct ref {
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ref(): p(0) { }
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ref(T *p_): p(p_) {
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_incref();
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}
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ref(const ref &o): p(o.p) {
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_incref();
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}
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ref &operator=(const ref &o) { reset(o.p); return *this; }
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~ref() { reset(); }
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void reset() {
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_decref();
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p = 0;
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}
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void reset(T *n) {
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if (n == p)
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return;
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_decref();
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p = n;
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_incref();
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}
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T *get() const { return p; }
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T *operator->() const { return p; }
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T &operator*() const { return *p; }
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operator bool() const { return p; }
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private:
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void _incref() {
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if (! p)
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return;
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incref(*p);
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}
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void _decref() {
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if (! p)
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return;
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decref(*p);
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}
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T *p;
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};
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} // namespace
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#endif
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