gslice.h revision 97403 
1// The template and inlines for the -*- C++ -*- gslice class.
2
3// Copyright (C) 1997, 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library.  This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 2, or (at your option)
9// any later version.
10
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14// GNU General Public License for more details.
15
16// You should have received a copy of the GNU General Public License along
17// with this library; see the file COPYING.  If not, write to the Free
18// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
19// USA.
20
21// As a special exception, you may use this file as part of a free software
22// library without restriction.  Specifically, if other files instantiate
23// templates or use macros or inline functions from this file, or you compile
24// this file and link it with other files to produce an executable, this
25// file does not by itself cause the resulting executable to be covered by
26// the GNU General Public License.  This exception does not however
27// invalidate any other reasons why the executable file might be covered by
28// the GNU General Public License.
29
30// Written by Gabriel Dos Reis <Gabriel.Dos-Reis@DPTMaths.ENS-Cachan.Fr>
31
32/** @file gslice.h
33 *  This is an internal header file, included by other library headers.
34 *  You should not attempt to use it directly.
35 */
36
37#ifndef _CPP_BITS_GSLICE_H
38#define _CPP_BITS_GSLICE_H 1
39
40#pragma GCC system_header
41
42namespace std {
43
44    class gslice
45    {
46    public:
47        gslice ();
48        gslice (size_t, const valarray<size_t>&, const valarray<size_t>&);
49        // XXX: the IS says the copy-ctor and copy-assignment operators are
50        //      synthetized by the compiler but they are just unsuitable
51        //      for a ref-counted semantic
52        gslice(const gslice&);
53        ~gslice();
54
55        // XXX: See the note above.
56        gslice& operator= (const gslice&);
57
58        size_t           start () const;
59        valarray<size_t> size () const;
60        valarray<size_t> stride () const;
61
62    private:
63        struct _Indexer {
64            size_t _M_count;
65            size_t _M_start;
66            valarray<size_t> _M_size;
67            valarray<size_t> _M_stride;
68            valarray<size_t> _M_index;
69            _Indexer(size_t, const valarray<size_t>&,
70                     const valarray<size_t>&);
71            void _M_increment_use() { ++_M_count; }
72            size_t _M_decrement_use() { return --_M_count; }
73        };
74
75        _Indexer* _M_index;
76
77        template<typename _Tp> friend class valarray;
78    };
79
80    inline size_t
81    gslice::start () const
82    { return _M_index ? _M_index->_M_start : 0; }
83
84    inline valarray<size_t>
85    gslice::size () const
86    { return _M_index ? _M_index->_M_size : valarray<size_t>(); }
87
88    inline valarray<size_t>
89    gslice::stride () const
90    { return _M_index ? _M_index->_M_stride : valarray<size_t>(); }
91
92    inline gslice::gslice () : _M_index(0) {}
93
94    inline
95    gslice::gslice(size_t __o, const valarray<size_t>& __l,
96                   const valarray<size_t>& __s)
97            : _M_index(new gslice::_Indexer(__o, __l, __s)) {}
98
99    inline
100    gslice::gslice(const gslice& __g) : _M_index(__g._M_index)
101    { if (_M_index) _M_index->_M_increment_use(); }
102
103    inline
104    gslice::~gslice()
105    { if (_M_index && _M_index->_M_decrement_use() == 0) delete _M_index; }
106
107    inline gslice&
108    gslice::operator= (const gslice& __g)
109    {
110        if (__g._M_index) __g._M_index->_M_increment_use();
111        if (_M_index && _M_index->_M_decrement_use() == 0) delete _M_index;
112        _M_index = __g._M_index;
113        return *this;
114    }
115
116
117} // std::
118
119
120#endif /* _CPP_BITS_GSLICE_H */
121
122// Local Variables:
123// mode:c++
124// End:
125