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//
// Copyright 2013 Francisco Jerez
//
// 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 CLOVER_UTIL_POINTER_HPP
#define CLOVER_UTIL_POINTER_HPP
#include <atomic>
namespace clover {
///
/// Base class for objects that support reference counting.
///
class ref_counter {
public:
ref_counter() : _ref_count(1) {}
unsigned
ref_count() {
return _ref_count;
}
void
retain() {
_ref_count++;
}
bool
release() {
return (--_ref_count) == 0;
}
private:
std::atomic<unsigned> _ref_count;
};
///
/// Intrusive smart pointer for objects that implement the
/// clover::ref_counter interface.
///
template<typename T>
class intrusive_ptr {
public:
intrusive_ptr(T *q = NULL) : p(q) {
if (p)
p->retain();
}
intrusive_ptr(const intrusive_ptr &ptr) :
intrusive_ptr(ptr.p) {
}
intrusive_ptr(intrusive_ptr &&ptr) :
p(ptr.p) {
ptr.p = NULL;
}
~intrusive_ptr() {
if (p && p->release())
delete p;
}
intrusive_ptr &
operator=(intrusive_ptr ptr) {
std::swap(ptr.p, p);
return *this;
}
bool
operator==(const intrusive_ptr &ref) const {
return p == ref.p;
}
bool
operator!=(const intrusive_ptr &ref) const {
return p != ref.p;
}
T &
operator*() const {
return *p;
}
T *
operator->() const {
return p;
}
T *
operator()() const {
return p;
}
explicit operator bool() const {
return p;
}
explicit operator T *() const {
return p;
}
private:
T *p;
};
///
/// Transfer the caller's ownership of a reference-counted object
/// to a clover::intrusive_ptr smart pointer.
///
template<typename T>
inline intrusive_ptr<T>
transfer(T *p) {
intrusive_ptr<T> ref { p };
p->release();
return ref;
}
///
/// Class that implements the usual pointer interface but in fact
/// contains the object it seems to be pointing to.
///
template<typename T>
class pseudo_ptr {
public:
pseudo_ptr(T x) : x(x) {
}
pseudo_ptr(const pseudo_ptr &p) : x(p.x) {
}
pseudo_ptr &
operator=(const pseudo_ptr &p) {
x = p.x;
return *this;
}
T &
operator*() {
return x;
}
T *
operator->() {
return &x;
}
explicit operator bool() const {
return true;
}
private:
T x;
};
}
#endif
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