/usr/include/ginac/ptr.h is in libginac-dev 1.6.2-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 | /** @file ptr.h
*
* Reference-counted pointer template. */
/*
* GiNaC Copyright (C) 1999-2011 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
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef GINAC_PTR_H
#define GINAC_PTR_H
#include "assertion.h"
#include <cstddef> // for size_t
#include <functional>
#include <iosfwd>
namespace GiNaC {
/** Base class for reference-counted objects. */
class refcounted {
public:
refcounted() throw() : refcount(0) {}
unsigned int add_reference() throw() { return ++refcount; }
unsigned int remove_reference() throw() { return --refcount; }
unsigned int get_refcount() const throw() { return refcount; }
void set_refcount(unsigned int r) throw() { refcount = r; }
private:
unsigned int refcount; ///< reference counter
};
/** Class of (intrusively) reference-counted pointers that support
* copy-on-write semantics.
*
* Requirements for T:
* 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> >;
// NB: This implementation of reference counting is not thread-safe.
// The reference counter needs to be incremented/decremented atomically,
// and makewritable() requires locking.
public:
// no default ctor: a ptr is never unbound
/** Bind ptr to newly created object, start reference counting. */
ptr(T *t) throw() : p(t) { GINAC_ASSERT(p); p->set_refcount(1); }
/** Bind ptr to existing reference-counted object. */
explicit ptr(T &t) throw() : p(&t) { p->add_reference(); }
ptr(const ptr & other) throw() : p(other.p) { p->add_reference(); }
~ptr()
{
if (p->remove_reference() == 0)
delete p;
}
ptr &operator=(const ptr & other)
{
// 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 = otherp;
return *this;
}
T &operator*() const throw() { return *p; }
T *operator->() const throw() { return p; }
friend inline T *get_pointer(const ptr & x) throw() { 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->get_refcount() > 1) {
T *p2 = p->duplicate();
p2->set_refcount(1);
p->remove_reference();
p = p2;
}
}
/** Swap the bound object of this ptr with another ptr. */
void swap(ptr & other) throw()
{
T *t = p;
p = other.p;
other.p = t;
}
// ptr<>s are always supposed to be bound to a valid object, so we don't
// provide support for "if (p)", "if (!p)", "if (p==0)" and "if (p!=0)".
// We do, however, provide support for comparing ptr<>s with other ptr<>s
// to different (probably derived) types and raw pointers.
template <class U>
bool operator==(const ptr<U> & rhs) const throw() { return p == get_pointer(rhs); }
template <class U>
bool operator!=(const ptr<U> & rhs) const throw() { return p != get_pointer(rhs); }
template <class U>
inline friend bool operator==(const ptr & lhs, const U * rhs) throw() { return lhs.p == rhs; }
template <class U>
inline friend bool operator!=(const ptr & lhs, const U * rhs) throw() { return lhs.p != rhs; }
template <class U>
inline friend bool operator==(const U * lhs, const ptr & rhs) throw() { return lhs == rhs.p; }
template <class U>
inline friend bool operator!=(const U * lhs, const ptr & rhs) throw() { return lhs != rhs.p; }
inline friend std::ostream & operator<<(std::ostream & os, const ptr<T> & rhs)
{
os << rhs.p;
return os;
}
private:
T *p;
};
} // 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> >
: public binary_function<GiNaC::ptr<T>, GiNaC::ptr<T>, bool> {
bool operator()(const GiNaC::ptr<T> &lhs, const GiNaC::ptr<T> &rhs) const
{
return less<T*>()(lhs.p, rhs.p);
}
};
} // namespace std
#endif // ndef GINAC_PTR_H
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