gslice.h

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// The template and inlines for the -*- C++ -*- gslice class.

// Copyright (C) 1997-1999 Cygnus Solutions
//
// This file is part of the GNU ISO C++ Library.  This library 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, or (at your option)
// any later version.

// This library 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 library; see the file COPYING.  If not, write to the Free
// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
// USA.

// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License.  This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.

// Written by Gabriel Dos Reis <[e-mail]>

#ifndef __GSLICE__
#define __GSLICE__

extern "C++" {

struct _Indexer {
    size_t _M_count;
    size_t _M_start;
    valarray<size_t> _M_size;
    valarray<size_t> _M_stride;
    valarray<size_t> _M_index;
    _Indexer(size_t, const valarray<size_t>&, const valarray<size_t>&);
    void _M_increment_use() { ++_M_count; }
    size_t _M_decrement_use() { return --_M_count; }
};

    
class gslice
{
public:
    gslice ();
    gslice (size_t, const valarray<size_t>&, const valarray<size_t>&);
    gslice(const gslice&);
    ~gslice();

    gslice& operator= (const gslice&);
    size_t           start () const;
    valarray<size_t> size () const;
    valarray<size_t> stride () const;
    
private:
    _Indexer* _M_index;
    
    template<typename _Tp> friend class valarray;
};
    
inline size_t
gslice::start () const
{ return _M_index ? _M_index->_M_start : 0; }

inline valarray<size_t>
gslice::size () const
{ return _M_index ? _M_index->_M_size : valarray<size_t>(); }

inline valarray<size_t>
gslice::stride () const
{ return _M_index ? _M_index->_M_stride : valarray<size_t>(); }

inline gslice::gslice () : _M_index(0) {}

inline
gslice::gslice(size_t __o, const valarray<size_t>& __l,
               const valarray<size_t>& __s)
        : _M_index(new _Indexer(__o, __l, __s)) {}

inline
gslice::gslice(const gslice& __g) : _M_index(__g._M_index)
{ if (_M_index) _M_index->_M_increment_use(); }

inline
gslice::~gslice()
{ if (_M_index && _M_index->_M_decrement_use() == 0) delete _M_index; }

inline gslice&
gslice::operator= (const gslice& __g)
{
    if (__g._M_index) __g._M_index->_M_increment_use();
    if (_M_index && _M_index->_M_decrement_use() == 0) delete _M_index;
    _M_index = __g._M_index;
    return *this;
}


} // extern "C++"

#endif // __GSLICE__

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// mode:c++
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