* Reference-counted pointer template. */
/*
- * GiNaC Copyright (C) 1999-2003 Johannes Gutenberg University Mainz, Germany
+ * GiNaC Copyright (C) 1999-2015 Johannes Gutenberg University Mainz, Germany
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
-#ifndef __GINAC_PTR_H__
-#define __GINAC_PTR_H__
+#ifndef GINAC_PTR_H
+#define GINAC_PTR_H
+#include "assertion.h"
+
+#include <cstddef> // for size_t
#include <functional>
#include <iosfwd>
-#include "assertion.h"
-
namespace GiNaC {
+/** Base class for reference-counted objects. */
+class refcounted {
+public:
+ refcounted() noexcept : refcount(0) {}
+
+ unsigned int add_reference() noexcept { return ++refcount; }
+ unsigned int remove_reference() noexcept { return --refcount; }
+ unsigned int get_refcount() const noexcept { return refcount; }
+ void set_refcount(unsigned int r) noexcept { refcount = r; }
+
+private:
+ unsigned int refcount; ///< reference counter
+};
+
+
/** Class of (intrusively) reference-counted pointers that support
* copy-on-write semantics.
*
* Requirements for T:
- * T::refcount member that supports ++refcount, --refcount, refcount = 1,
- * refcount == 0 and refcount > 1
+ * must support the refcounted interface (usually by being derived
+ * from refcounted)
* T* T::duplicate() member function (only if makewriteable() is used) */
template <class T> class ptr {
- friend class std::less< ptr<T> >;
+ friend struct std::less<ptr<T>>;
// NB: This implementation of reference counting is not thread-safe.
// The reference counter needs to be incremented/decremented atomically,
// no default ctor: a ptr is never unbound
/** Bind ptr to newly created object, start reference counting. */
- ptr(T *t) : p(t) { GINAC_ASSERT(p); p->refcount = 1; }
+ ptr(T *t) noexcept : p(t) { GINAC_ASSERT(p); p->set_refcount(1); }
/** Bind ptr to existing reference-counted object. */
- explicit ptr(T &t) : p(&t) { ++p->refcount; }
+ explicit ptr(T &t) noexcept : p(&t) { p->add_reference(); }
- ptr(const ptr & other) : p(other.p) { ++p->refcount; }
+ ptr(const ptr & other) noexcept : p(other.p) { p->add_reference(); }
~ptr()
{
- if (--p->refcount == 0)
+ if (p->remove_reference() == 0)
delete p;
}
ptr &operator=(const ptr & other)
{
- // NB: must first increment other.p->refcount, since other might be *this.
- ++other.p->refcount;
- if (--p->refcount == 0)
+ // NB1: Must first add reference to "other", since other might be *this.
+ // NB2: Cache other.p, because if "other" is a subexpression of p,
+ // deleting p will also invalidate "other".
+ T *otherp = other.p;
+ otherp->add_reference();
+ if (p->remove_reference() == 0)
delete p;
- p = other.p;
+ p = otherp;
return *this;
}
- T &operator*() const { return *p; }
- T *operator->() const { return p; }
+ T &operator*() const noexcept { return *p; }
+ T *operator->() const noexcept { return p; }
- friend inline T *get_pointer(const ptr & x) { return x.p; }
+ friend inline T *get_pointer(const ptr & x) noexcept { return x.p; }
/** Announce your intention to modify the object bound to this ptr.
* This ensures that the object is not shared by any other ptrs. */
void makewritable()
{
- if (p->refcount > 1) {
+ if (p->get_refcount() > 1) {
T *p2 = p->duplicate();
- p2->refcount = 1;
- --p->refcount;
+ p2->set_refcount(1);
+ p->remove_reference();
p = p2;
}
}
/** Swap the bound object of this ptr with another ptr. */
- void swap(ptr & other)
+ void swap(ptr & other) noexcept
{
T *t = p;
p = other.p;
// to different (probably derived) types and raw pointers.
template <class U>
- bool operator==(const ptr<U> & rhs) const { return p == get_pointer(rhs); }
+ bool operator==(const ptr<U> & rhs) const noexcept { return p == get_pointer(rhs); }
template <class U>
- bool operator!=(const ptr<U> & rhs) const { return p != get_pointer(rhs); }
+ bool operator!=(const ptr<U> & rhs) const noexcept { return p != get_pointer(rhs); }
template <class U>
- inline friend bool operator==(const ptr & lhs, const U * rhs) { return lhs.p == rhs; }
+ inline friend bool operator==(const ptr & lhs, const U * rhs) noexcept { return lhs.p == rhs; }
template <class U>
- inline friend bool operator!=(const ptr & lhs, const U * rhs) { return lhs.p != rhs; }
+ inline friend bool operator!=(const ptr & lhs, const U * rhs) noexcept { return lhs.p != rhs; }
template <class U>
- inline friend bool operator==(const U * lhs, const ptr & rhs) { return lhs == rhs.p; }
+ inline friend bool operator==(const U * lhs, const ptr & rhs) noexcept { return lhs == rhs.p; }
template <class U>
- inline friend bool operator!=(const U * lhs, const ptr & rhs) { return lhs != rhs.p; }
+ inline friend bool operator!=(const U * lhs, const ptr & rhs) noexcept { return lhs != rhs.p; }
inline friend std::ostream & operator<<(std::ostream & os, const ptr<T> & rhs)
{
os << rhs.p;
+ return os;
}
private:
} // namespace GiNaC
+
namespace std {
/** Specialization of std::less for ptr<T> to enable ordering of ptr<T>
* objects (e.g. for the use as std::map keys). */
-template <class T> struct less< GiNaC::ptr<T> >
+template <class T> struct less<GiNaC::ptr<T>>
: public binary_function<GiNaC::ptr<T>, GiNaC::ptr<T>, bool> {
bool operator()(const GiNaC::ptr<T> &lhs, const GiNaC::ptr<T> &rhs) const
{
} // namespace std
-#endif // ndef __GINAC_UTILS_H__
+#endif // ndef GINAC_PTR_H
git://www.ginac.de / ginac.git / blobdiff