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gslice.h

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00001 // The template and inlines for the -*- C++ -*- gslice class.
00002 
00003 // Copyright (C) 1997-2001 Free Software Foundation, Inc.
00004 //
00005 // This file is part of the GNU ISO C++ Library.  This library is free
00006 // software; you can redistribute it and/or modify it under the
00007 // terms of the GNU General Public License as published by the
00008 // Free Software Foundation; either version 2, or (at your option)
00009 // any later version.
00010 
00011 // This library is distributed in the hope that it will be useful,
00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014 // GNU General Public License for more details.
00015 
00016 // You should have received a copy of the GNU General Public License along
00017 // with this library; see the file COPYING.  If not, write to the Free
00018 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
00019 // USA.
00020 
00021 // As a special exception, you may use this file as part of a free software
00022 // library without restriction.  Specifically, if other files instantiate
00023 // templates or use macros or inline functions from this file, or you compile
00024 // this file and link it with other files to produce an executable, this
00025 // file does not by itself cause the resulting executable to be covered by
00026 // the GNU General Public License.  This exception does not however
00027 // invalidate any other reasons why the executable file might be covered by
00028 // the GNU General Public License.
00029 
00030 // Written by Gabriel Dos Reis <Gabriel.Dos-Reis@DPTMaths.ENS-Cachan.Fr>
00031 
00032 #ifndef _CPP_BITS_GSLICE_H
00033 #define _CPP_BITS_GSLICE_H 1
00034 
00035 #pragma GCC system_header
00036 
00037 namespace std {
00038     
00039     class gslice
00040     {
00041     public:
00042         gslice ();
00043         gslice (size_t, const valarray<size_t>&, const valarray<size_t>&);
00044         // XXX: the IS says the copy-ctor and copy-assignment operators are
00045         //      synthetized by the compiler but they are just unsuitable
00046         //      for a ref-counted semantic
00047         gslice(const gslice&);
00048         ~gslice();
00049 
00050         // XXX: See the note above.
00051         gslice& operator= (const gslice&);
00052         
00053         size_t           start () const;
00054         valarray<size_t> size () const;
00055         valarray<size_t> stride () const;
00056         
00057     private:
00058         struct _Indexer {
00059             size_t _M_count;
00060             size_t _M_start;
00061             valarray<size_t> _M_size;
00062             valarray<size_t> _M_stride;
00063             valarray<size_t> _M_index;
00064             _Indexer(size_t, const valarray<size_t>&,
00065                      const valarray<size_t>&);
00066             void _M_increment_use() { ++_M_count; }
00067             size_t _M_decrement_use() { return --_M_count; }
00068         };
00069 
00070         _Indexer* _M_index;
00071         
00072         template<typename _Tp> friend class valarray;
00073     };
00074     
00075     inline size_t
00076     gslice::start () const
00077     { return _M_index ? _M_index->_M_start : 0; }
00078     
00079     inline valarray<size_t>
00080     gslice::size () const
00081     { return _M_index ? _M_index->_M_size : valarray<size_t>(); }
00082     
00083     inline valarray<size_t>
00084     gslice::stride () const
00085     { return _M_index ? _M_index->_M_stride : valarray<size_t>(); }
00086     
00087     inline gslice::gslice () : _M_index(0) {}
00088 
00089     inline
00090     gslice::gslice(size_t __o, const valarray<size_t>& __l,
00091                    const valarray<size_t>& __s)
00092             : _M_index(new gslice::_Indexer(__o, __l, __s)) {}
00093 
00094     inline
00095     gslice::gslice(const gslice& __g) : _M_index(__g._M_index)
00096     { if (_M_index) _M_index->_M_increment_use(); }
00097     
00098     inline
00099     gslice::~gslice()
00100     { if (_M_index && _M_index->_M_decrement_use() == 0) delete _M_index; }
00101 
00102     inline gslice&
00103     gslice::operator= (const gslice& __g)
00104     {
00105         if (__g._M_index) __g._M_index->_M_increment_use();
00106         if (_M_index && _M_index->_M_decrement_use() == 0) delete _M_index;
00107         _M_index = __g._M_index;
00108         return *this;
00109     }
00110             
00111     
00112 } // std::
00113 
00114 
00115 #endif /* _CPP_BITS_GSLICE_H */
00116 
00117 // Local Variables:
00118 // mode:c++
00119 // End:

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