headers/cpp/std/gslice.h

   1 // The template and inlines for the -*- C++ -*- gslice class.
   2
   3 // Copyright (C) 1997-1999 Cygnus Solutions
   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 #ifndef __GSLICE__
  33 #define __GSLICE__
  34
  35 extern "C++" {
  36
  37 struct _Indexer {
  38     size_t _M_count;
  39     size_t _M_start;
  40     valarray<size_t> _M_size;
  41     valarray<size_t> _M_stride;
  42     valarray<size_t> _M_index;
  43     _Indexer(size_t, const valarray<size_t>&, const valarray<size_t>&);
  44     void _M_increment_use() { ++_M_count; }
  45     size_t _M_decrement_use() { return --_M_count; }
  46 };
  47
  48
  49 class gslice
  50 {
  51 public:
  52     gslice ();
  53     gslice (size_t, const valarray<size_t>&, const valarray<size_t>&);
  54     gslice(const gslice&);
  55     ~gslice();
  56
  57     gslice& operator= (const gslice&);
  58     size_t           start () const;
  59     valarray<size_t> size () const;
  60     valarray<size_t> stride () const;
  61
  62 private:
  63     _Indexer* _M_index;
  64
  65     template<typename _Tp> friend class valarray;
  66 };
  67
  68 inline size_t
  69 gslice::start () const
  70 { return _M_index ? _M_index->_M_start : 0; }
  71
  72 inline valarray<size_t>
  73 gslice::size () const
  74 { return _M_index ? _M_index->_M_size : valarray<size_t>(); }
  75
  76 inline valarray<size_t>
  77 gslice::stride () const
  78 { return _M_index ? _M_index->_M_stride : valarray<size_t>(); }
  79
  80 inline gslice::gslice () : _M_index(0) {}
  81
  82 inline
  83 gslice::gslice(size_t __o, const valarray<size_t>& __l,
  84                const valarray<size_t>& __s)
  85         : _M_index(new _Indexer(__o, __l, __s)) {}
  86
  87 inline
  88 gslice::gslice(const gslice& __g) : _M_index(__g._M_index)
  89 { if (_M_index) _M_index->_M_increment_use(); }
  90
  91 inline
  92 gslice::~gslice()
  93 { if (_M_index && _M_index->_M_decrement_use() == 0) delete _M_index; }
  94
  95 inline gslice&
  96 gslice::operator= (const gslice& __g)
  97 {
  98     if (__g._M_index) __g._M_index->_M_increment_use();
  99     if (_M_index && _M_index->_M_decrement_use() == 0) delete _M_index;
 100     _M_index = __g._M_index;
 101     return *this;
 102 }
 103
 104
 105 } // extern "C++"
 106
 107 #endif // __GSLICE__
 108
 109 // Local Variables:
 110 // mode:c++
 111 // End: