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      1 // The template and inlines for the -*- C++ -*- mask_array class.
      2 
      3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2004, 2005, 2009, 2010
      4 //  Free Software Foundation, Inc.
      5 //
      6 // This file is part of the GNU ISO C++ Library.  This library is free
      7 // software; you can redistribute it and/or modify it under the
      8 // terms of the GNU General Public License as published by the
      9 // Free Software Foundation; either version 3, or (at your option)
     10 // any later version.
     11 
     12 // This library is distributed in the hope that it will be useful,
     13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
     14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     15 // GNU General Public License for more details.
     16 
     17 // Under Section 7 of GPL version 3, you are granted additional
     18 // permissions described in the GCC Runtime Library Exception, version
     19 // 3.1, as published by the Free Software Foundation.
     20 
     21 // You should have received a copy of the GNU General Public License and
     22 // a copy of the GCC Runtime Library Exception along with this program;
     23 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
     24 // <http://www.gnu.org/licenses/>.
     25 
     26 /** @file bits/mask_array.h
     27  *  This is an internal header file, included by other library headers.
     28  *  Do not attempt to use it directly. @headername{valarray}
     29  */
     30 
     31 // Written by Gabriel Dos Reis <Gabriel.Dos-Reis (at) DPTMaths.ENS-Cachan.Fr>
     32 
     33 #ifndef _MASK_ARRAY_H
     34 #define _MASK_ARRAY_H 1
     35 
     36 #pragma GCC system_header
     37 
     38 namespace std _GLIBCXX_VISIBILITY(default)
     39 {
     40 _GLIBCXX_BEGIN_NAMESPACE_VERSION
     41 
     42   /**
     43    * @addtogroup numeric_arrays
     44    * @{
     45    */
     46 
     47   /**
     48    *  @brief  Reference to selected subset of an array.
     49    *
     50    *  A mask_array is a reference to the actual elements of an array specified
     51    *  by a bitmask in the form of an array of bool.  The way to get a
     52    *  mask_array is to call operator[](valarray<bool>) on a valarray.  The
     53    *  returned mask_array then permits carrying operations out on the
     54    *  referenced subset of elements in the original valarray.
     55    *
     56    *  For example, if a mask_array is obtained using the array (false, true,
     57    *  false, true) as an argument, the mask array has two elements referring
     58    *  to array[1] and array[3] in the underlying array.
     59    *
     60    *  @param  Tp  Element type.
     61    */
     62   template <class _Tp>
     63     class mask_array
     64     {
     65     public:
     66       typedef _Tp value_type;
     67 
     68       // _GLIBCXX_RESOLVE_LIB_DEFECTS
     69       // 253. valarray helper functions are almost entirely useless
     70 
     71       ///  Copy constructor.  Both slices refer to the same underlying array.
     72       mask_array (const mask_array&);
     73 
     74       ///  Assignment operator.  Assigns elements to corresponding elements
     75       ///  of @a a.
     76       mask_array& operator=(const mask_array&);
     77 
     78       void operator=(const valarray<_Tp>&) const;
     79       ///  Multiply slice elements by corresponding elements of @a v.
     80       void operator*=(const valarray<_Tp>&) const;
     81       ///  Divide slice elements by corresponding elements of @a v.
     82       void operator/=(const valarray<_Tp>&) const;
     83       ///  Modulo slice elements by corresponding elements of @a v.
     84       void operator%=(const valarray<_Tp>&) const;
     85       ///  Add corresponding elements of @a v to slice elements.
     86       void operator+=(const valarray<_Tp>&) const;
     87       ///  Subtract corresponding elements of @a v from slice elements.
     88       void operator-=(const valarray<_Tp>&) const;
     89       ///  Logical xor slice elements with corresponding elements of @a v.
     90       void operator^=(const valarray<_Tp>&) const;
     91       ///  Logical and slice elements with corresponding elements of @a v.
     92       void operator&=(const valarray<_Tp>&) const;
     93       ///  Logical or slice elements with corresponding elements of @a v.
     94       void operator|=(const valarray<_Tp>&) const;
     95       ///  Left shift slice elements by corresponding elements of @a v.
     96       void operator<<=(const valarray<_Tp>&) const;
     97       ///  Right shift slice elements by corresponding elements of @a v.
     98       void operator>>=(const valarray<_Tp>&) const;
     99       ///  Assign all slice elements to @a t.
    100       void operator=(const _Tp&) const;
    101 
    102         //        ~mask_array ();
    103 
    104       template<class _Dom>
    105         void operator=(const _Expr<_Dom,_Tp>&) const;
    106       template<class _Dom>
    107         void operator*=(const _Expr<_Dom,_Tp>&) const;
    108       template<class _Dom>
    109         void operator/=(const _Expr<_Dom,_Tp>&) const;
    110       template<class _Dom>
    111         void operator%=(const _Expr<_Dom,_Tp>&) const;
    112       template<class _Dom>
    113         void operator+=(const _Expr<_Dom,_Tp>&) const;
    114       template<class _Dom>
    115         void operator-=(const _Expr<_Dom,_Tp>&) const;
    116       template<class _Dom>
    117         void operator^=(const _Expr<_Dom,_Tp>&) const;
    118       template<class _Dom>
    119         void operator&=(const _Expr<_Dom,_Tp>&) const;
    120       template<class _Dom>
    121         void operator|=(const _Expr<_Dom,_Tp>&) const;
    122       template<class _Dom>
    123         void operator<<=(const _Expr<_Dom,_Tp>&) const;
    124       template<class _Dom>
    125         void operator>>=(const _Expr<_Dom,_Tp>&) const;
    126 
    127     private:
    128       mask_array(_Array<_Tp>, size_t, _Array<bool>);
    129       friend class valarray<_Tp>;
    130 
    131       const size_t       _M_sz;
    132       const _Array<bool> _M_mask;
    133       const _Array<_Tp>  _M_array;
    134 
    135       // not implemented
    136       mask_array();
    137     };
    138 
    139   template<typename _Tp>
    140     inline mask_array<_Tp>::mask_array(const mask_array<_Tp>& a)
    141     : _M_sz(a._M_sz), _M_mask(a._M_mask), _M_array(a._M_array) {}
    142 
    143   template<typename _Tp>
    144     inline
    145     mask_array<_Tp>::mask_array(_Array<_Tp> __a, size_t __s, _Array<bool> __m)
    146     : _M_sz(__s), _M_mask(__m), _M_array(__a) {}
    147 
    148   template<typename _Tp>
    149     inline mask_array<_Tp>&
    150     mask_array<_Tp>::operator=(const mask_array<_Tp>& __a)
    151     {
    152       std::__valarray_copy(__a._M_array, __a._M_mask,
    153 			   _M_sz, _M_array, _M_mask);
    154       return *this;
    155     }
    156 
    157   template<typename _Tp>
    158     inline void
    159     mask_array<_Tp>::operator=(const _Tp& __t) const
    160     { std::__valarray_fill(_M_array, _M_sz, _M_mask, __t); }
    161 
    162   template<typename _Tp>
    163     inline void
    164     mask_array<_Tp>::operator=(const valarray<_Tp>& __v) const
    165     { std::__valarray_copy(_Array<_Tp>(__v), __v.size(), _M_array, _M_mask); }
    166 
    167   template<typename _Tp>
    168     template<class _Ex>
    169       inline void
    170       mask_array<_Tp>::operator=(const _Expr<_Ex, _Tp>& __e) const
    171       { std::__valarray_copy(__e, __e.size(), _M_array, _M_mask); }
    172 
    173 #undef _DEFINE_VALARRAY_OPERATOR
    174 #define _DEFINE_VALARRAY_OPERATOR(_Op, _Name)				\
    175   template<typename _Tp>						\
    176     inline void								\
    177     mask_array<_Tp>::operator _Op##=(const valarray<_Tp>& __v) const	\
    178     {									\
    179       _Array_augmented_##_Name(_M_array, _M_mask,			\
    180 			       _Array<_Tp>(__v), __v.size());		\
    181     }									\
    182 									\
    183   template<typename _Tp>                                                \
    184     template<class _Dom>			                        \
    185       inline void							\
    186       mask_array<_Tp>::operator _Op##=(const _Expr<_Dom, _Tp>& __e) const\
    187       {									\
    188 	_Array_augmented_##_Name(_M_array, _M_mask, __e, __e.size());   \
    189       }
    190 
    191 _DEFINE_VALARRAY_OPERATOR(*, __multiplies)
    192 _DEFINE_VALARRAY_OPERATOR(/, __divides)
    193 _DEFINE_VALARRAY_OPERATOR(%, __modulus)
    194 _DEFINE_VALARRAY_OPERATOR(+, __plus)
    195 _DEFINE_VALARRAY_OPERATOR(-, __minus)
    196 _DEFINE_VALARRAY_OPERATOR(^, __bitwise_xor)
    197 _DEFINE_VALARRAY_OPERATOR(&, __bitwise_and)
    198 _DEFINE_VALARRAY_OPERATOR(|, __bitwise_or)
    199 _DEFINE_VALARRAY_OPERATOR(<<, __shift_left)
    200 _DEFINE_VALARRAY_OPERATOR(>>, __shift_right)
    201 
    202 #undef _DEFINE_VALARRAY_OPERATOR
    203 
    204   // @} group numeric_arrays
    205 
    206 _GLIBCXX_END_NAMESPACE_VERSION
    207 } // namespace
    208 
    209 #endif /* _MASK_ARRAY_H */
    210