indirect_array.h

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

// Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2004
//  Free Software Foundation, Inc.
//
// 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]>

/** @file indirect_array.h
 *  This is an internal header file, included by other library headers.
 *  You should not attempt to use it directly.
 */

#ifndef _INDIRECT_ARRAY_H
#define _INDIRECT_ARRAY_H 1

//#pragma GCC system_header

namespace std
{
    /**
     *  @brief  Reference to arbitrary subset of an array.
     *
     *  An indirect_array is a reference to the actual elements of an array
     *  specified by an ordered array of indices.  The way to get an indirect_array is to
     *  call operator[](valarray<size_t>) on a valarray.  The returned
     *  indirect_array then permits carrying operations out on the referenced
     *  subset of elements in the original valarray.
     *
     *  For example, if an indirect_array is obtained using the array (4,2,0) as
     *  an argument, and then assigned to an array containing (1,2,3), then the
     *  underlying array will have array[0]==3, array[2]==2, and array[4]==1.
     *
     *  @param  Tp  Element type.
     */
    template <class _Tp>
        class indirect_array
        {
            public:
                typedef _Tp value_type;

                // _GLIBCXX_RESOLVE_LIB_DEFECTS
                // 253. valarray helper functions are almost entirely useless

                ///  Copy constructor.  Both slices refer to the same underlying array.
                indirect_array(const indirect_array&);

                ///  Assignment operator.  Assigns elements to corresponding elements
                ///  of @a a.
                indirect_array& operator=(const indirect_array&);

                ///  Assign slice elements to corresponding elements of @a v.
                void operator=(const valarray<_Tp>&) const;
                ///  Multiply slice elements by corresponding elements of @a v.
                void operator*=(const valarray<_Tp>&) const;
                ///  Divide slice elements by corresponding elements of @a v.
                void operator/=(const valarray<_Tp>&) const;
                ///  Modulo slice elements by corresponding elements of @a v.
                void operator%=(const valarray<_Tp>&) const;
                ///  Add corresponding elements of @a v to slice elements.
                void operator+=(const valarray<_Tp>&) const;
                ///  Subtract corresponding elements of @a v from slice elements.
                void operator-=(const valarray<_Tp>&) const;
                ///  Logical xor slice elements with corresponding elements of @a v.
                void operator^=(const valarray<_Tp>&) const;
                ///  Logical and slice elements with corresponding elements of @a v.
                void operator&=(const valarray<_Tp>&) const;
                ///  Logical or slice elements with corresponding elements of @a v.
                void operator|=(const valarray<_Tp>&) const;
                ///  Left shift slice elements by corresponding elements of @a v.
                void operator<<=(const valarray<_Tp>&) const;
                ///  Right shift slice elements by corresponding elements of @a v.
                void operator>>=(const valarray<_Tp>&) const;
                ///  Assign all slice elements to @a t.
                void operator= (const _Tp&) const;
                //    ~indirect_array();

                template<class _Dom>
                    void operator=(const _Expr<_Dom, _Tp>&) const;
                template<class _Dom>
                    void operator*=(const _Expr<_Dom, _Tp>&) const;
                template<class _Dom>
                    void operator/=(const _Expr<_Dom, _Tp>&) const;
                template<class _Dom>
                    void operator%=(const _Expr<_Dom, _Tp>&) const;
                template<class _Dom>
                    void operator+=(const _Expr<_Dom, _Tp>&) const;
                template<class _Dom>
                    void operator-=(const _Expr<_Dom, _Tp>&) const;
                template<class _Dom>
                    void operator^=(const _Expr<_Dom, _Tp>&) const;
                template<class _Dom>
                    void operator&=(const _Expr<_Dom, _Tp>&) const;
                template<class _Dom>
                    void operator|=(const _Expr<_Dom, _Tp>&) const;
                template<class _Dom>
                    void operator<<=(const _Expr<_Dom, _Tp>&) const;
                template<class _Dom>
                    void operator>>=(const _Expr<_Dom, _Tp>&) const;

            private:
                ///  Copy constructor.  Both slices refer to the same underlying array.
                indirect_array(_Array<_Tp>, size_t, _Array<size_t>);

                friend class valarray<_Tp>;
                friend class gslice_array<_Tp>;

                const size_t	 _M_sz;
                const _Array<size_t> _M_index;
                const _Array<_Tp>	 _M_array;

                // not implemented
                indirect_array();
        };

    template<typename _Tp>
        inline
        indirect_array<_Tp>::indirect_array(const indirect_array<_Tp>& __a)
        : _M_sz(__a._M_sz), _M_index(__a._M_index), _M_array(__a._M_array) {}

    template<typename _Tp>
        inline
        indirect_array<_Tp>::indirect_array(_Array<_Tp> __a, size_t __s,
                _Array<size_t> __i)
        : _M_sz(__s), _M_index(__i), _M_array(__a) {}

    template<typename _Tp>
        inline indirect_array<_Tp>&
        indirect_array<_Tp>::operator=(const indirect_array<_Tp>& __a)
        {
            std::__valarray_copy(__a._M_array, _M_sz, __a._M_index, _M_array, _M_index);
            return *this;
        }


    template<typename _Tp>
        inline void
        indirect_array<_Tp>::operator=(const _Tp& __t) const
        { std::__valarray_fill(_M_array, _M_index, _M_sz, __t); }

    template<typename _Tp>
        inline void
        indirect_array<_Tp>::operator=(const valarray<_Tp>& __v) const
        { std::__valarray_copy(_Array<_Tp>(__v), _M_sz, _M_array, _M_index); }

    template<typename _Tp>
        template<class _Dom>
        inline void
        indirect_array<_Tp>::operator=(const _Expr<_Dom,_Tp>& __e) const
        { std::__valarray_copy(__e, _M_sz, _M_array, _M_index); }

#undef _DEFINE_VALARRAY_OPERATOR
#define _DEFINE_VALARRAY_OPERATOR(_Op, _Name)				\
    template<typename _Tp>						\
    inline void								\
    indirect_array<_Tp>::operator _Op##=(const valarray<_Tp>& __v) const\
    {									\
        _Array_augmented_##_Name(_M_array, _M_index, _Array<_Tp>(__v), _M_sz); \
    }									\
    \
    template<typename _Tp>                                                \
    template<class _Dom>				                \
    inline void							\
    indirect_array<_Tp>::operator _Op##=(const _Expr<_Dom,_Tp>& __e) const\
    {									\
        _Array_augmented_##_Name(_M_array, _M_index, __e, _M_sz);	\
    }

    _DEFINE_VALARRAY_OPERATOR(*, __multiplies)
        _DEFINE_VALARRAY_OPERATOR(/, __divides)
        _DEFINE_VALARRAY_OPERATOR(%, __modulus)
        _DEFINE_VALARRAY_OPERATOR(+, __plus)
        _DEFINE_VALARRAY_OPERATOR(-, __minus)
        _DEFINE_VALARRAY_OPERATOR(^, __bitwise_xor)
        _DEFINE_VALARRAY_OPERATOR(&, __bitwise_and)
        _DEFINE_VALARRAY_OPERATOR(|, __bitwise_or)
        _DEFINE_VALARRAY_OPERATOR(<<, __shift_left)
        _DEFINE_VALARRAY_OPERATOR(>>, __shift_right)

#undef _DEFINE_VALARRAY_OPERATOR

} // std::

#endif /* _INDIRECT_ARRAY_H */

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