183 lines
5.3 KiB
C++
183 lines
5.3 KiB
C++
// The template and inlines for the -*- C++ -*- gslice class.
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// Copyright (C) 1997, 1998, 1999, 2000, 2001, 2004, 2005, 2006, 2009, 2010
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// Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/** @file bits/gslice.h
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* This is an internal header file, included by other library headers.
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* Do not attempt to use it directly. @headername{valarray}
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*/
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// Written by Gabriel Dos Reis <Gabriel.Dos-Reis@DPTMaths.ENS-Cachan.Fr>
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#ifndef _GSLICE_H
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#define _GSLICE_H 1
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#pragma GCC system_header
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_GLIBCXX_BEGIN_NAMESPACE(std)
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/**
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* @addtogroup numeric_arrays
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* @{
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*/
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/**
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* @brief Class defining multi-dimensional subset of an array.
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*
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* The slice class represents a multi-dimensional subset of an array,
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* specified by three parameter sets: start offset, size array, and stride
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* array. The start offset is the index of the first element of the array
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* that is part of the subset. The size and stride array describe each
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* dimension of the slice. Size is the number of elements in that
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* dimension, and stride is the distance in the array between successive
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* elements in that dimension. Each dimension's size and stride is taken
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* to begin at an array element described by the previous dimension. The
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* size array and stride array must be the same size.
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*
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* For example, if you have offset==3, stride[0]==11, size[1]==3,
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* stride[1]==3, then slice[0,0]==array[3], slice[0,1]==array[6],
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* slice[0,2]==array[9], slice[1,0]==array[14], slice[1,1]==array[17],
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* slice[1,2]==array[20].
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*/
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class gslice
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{
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public:
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/// Construct an empty slice.
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gslice();
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/**
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* @brief Construct a slice.
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*
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* Constructs a slice with as many dimensions as the length of the @a l
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* and @a s arrays.
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*
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* @param o Offset in array of first element.
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* @param l Array of dimension lengths.
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* @param s Array of dimension strides between array elements.
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*/
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gslice(size_t, const valarray<size_t>&, const valarray<size_t>&);
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// XXX: the IS says the copy-ctor and copy-assignment operators are
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// synthesized by the compiler but they are just unsuitable
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// for a ref-counted semantic
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/// Copy constructor.
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gslice(const gslice&);
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/// Destructor.
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~gslice();
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// XXX: See the note above.
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/// Assignment operator.
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gslice& operator=(const gslice&);
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/// Return array offset of first slice element.
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size_t start() const;
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/// Return array of sizes of slice dimensions.
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valarray<size_t> size() const;
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/// Return array of array strides for each dimension.
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valarray<size_t> stride() const;
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private:
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struct _Indexer
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{
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size_t _M_count;
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size_t _M_start;
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valarray<size_t> _M_size;
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valarray<size_t> _M_stride;
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valarray<size_t> _M_index; // Linear array of referenced indices
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_Indexer()
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: _M_count(1), _M_start(0), _M_size(), _M_stride(), _M_index() {}
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_Indexer(size_t, const valarray<size_t>&,
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const valarray<size_t>&);
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void
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_M_increment_use()
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{ ++_M_count; }
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size_t
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_M_decrement_use()
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{ return --_M_count; }
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};
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_Indexer* _M_index;
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template<typename _Tp> friend class valarray;
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};
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inline size_t
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gslice::start() const
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{ return _M_index ? _M_index->_M_start : 0; }
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inline valarray<size_t>
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gslice::size() const
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{ return _M_index ? _M_index->_M_size : valarray<size_t>(); }
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inline valarray<size_t>
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gslice::stride() const
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{ return _M_index ? _M_index->_M_stride : valarray<size_t>(); }
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// _GLIBCXX_RESOLVE_LIB_DEFECTS
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// 543. valarray slice default constructor
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inline
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gslice::gslice()
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: _M_index(new gslice::_Indexer()) {}
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inline
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gslice::gslice(size_t __o, const valarray<size_t>& __l,
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const valarray<size_t>& __s)
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: _M_index(new gslice::_Indexer(__o, __l, __s)) {}
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inline
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gslice::gslice(const gslice& __g)
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: _M_index(__g._M_index)
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{ if (_M_index) _M_index->_M_increment_use(); }
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inline
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gslice::~gslice()
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{
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if (_M_index && _M_index->_M_decrement_use() == 0)
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delete _M_index;
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}
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inline gslice&
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gslice::operator=(const gslice& __g)
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{
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if (__g._M_index)
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__g._M_index->_M_increment_use();
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if (_M_index && _M_index->_M_decrement_use() == 0)
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delete _M_index;
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_M_index = __g._M_index;
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return *this;
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}
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// @} group numeric_arrays
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_GLIBCXX_END_NAMESPACE
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#endif /* _GSLICE_H */
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