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      1 // The template and inlines for the -*- C++ -*- mask_array class.
      2 
      3 // Copyright (C) 1997-2013 Free Software Foundation, Inc.
      4 //
      5 // This file is part of the GNU ISO C++ Library.  This library is free
      6 // software; you can redistribute it and/or modify it under the
      7 // terms of the GNU General Public License as published by the
      8 // Free Software Foundation; either version 3, or (at your option)
      9 // any later version.
     10 
     11 // This library is distributed in the hope that it will be useful,
     12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
     13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     14 // GNU General Public License for more details.
     15 
     16 // Under Section 7 of GPL version 3, you are granted additional
     17 // permissions described in the GCC Runtime Library Exception, version
     18 // 3.1, as published by the Free Software Foundation.
     19 
     20 // You should have received a copy of the GNU General Public License and
     21 // a copy of the GCC Runtime Library Exception along with this program;
     22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
     23 // <http://www.gnu.org/licenses/>.
     24 
     25 /** @file bits/mask_array.h
     26  *  This is an internal header file, included by other library headers.
     27  *  Do not attempt to use it directly. @headername{valarray}
     28  */
     29 
     30 // Written by Gabriel Dos Reis <Gabriel.Dos-Reis (at) DPTMaths.ENS-Cachan.Fr>
     31 
     32 #ifndef _MASK_ARRAY_H
     33 #define _MASK_ARRAY_H 1
     34 
     35 #pragma GCC system_header
     36 
     37 namespace std _GLIBCXX_VISIBILITY(default)
     38 {
     39 _GLIBCXX_BEGIN_NAMESPACE_VERSION
     40 
     41   /**
     42    * @addtogroup numeric_arrays
     43    * @{
     44    */
     45 
     46   /**
     47    *  @brief  Reference to selected subset of an array.
     48    *
     49    *  A mask_array is a reference to the actual elements of an array specified
     50    *  by a bitmask in the form of an array of bool.  The way to get a
     51    *  mask_array is to call operator[](valarray<bool>) on a valarray.  The
     52    *  returned mask_array then permits carrying operations out on the
     53    *  referenced subset of elements in the original valarray.
     54    *
     55    *  For example, if a mask_array is obtained using the array (false, true,
     56    *  false, true) as an argument, the mask array has two elements referring
     57    *  to array[1] and array[3] in the underlying array.
     58    *
     59    *  @param  Tp  Element type.
     60    */
     61   template <class _Tp>
     62     class mask_array
     63     {
     64     public:
     65       typedef _Tp value_type;
     66 
     67       // _GLIBCXX_RESOLVE_LIB_DEFECTS
     68       // 253. valarray helper functions are almost entirely useless
     69 
     70       ///  Copy constructor.  Both slices refer to the same underlying array.
     71       mask_array (const mask_array&);
     72 
     73       ///  Assignment operator.  Assigns elements to corresponding elements
     74       ///  of @a a.
     75       mask_array& operator=(const mask_array&);
     76 
     77       void operator=(const valarray<_Tp>&) const;
     78       ///  Multiply slice elements by corresponding elements of @a v.
     79       void operator*=(const valarray<_Tp>&) const;
     80       ///  Divide slice elements by corresponding elements of @a v.
     81       void operator/=(const valarray<_Tp>&) const;
     82       ///  Modulo slice elements by corresponding elements of @a v.
     83       void operator%=(const valarray<_Tp>&) const;
     84       ///  Add corresponding elements of @a v to slice elements.
     85       void operator+=(const valarray<_Tp>&) const;
     86       ///  Subtract corresponding elements of @a v from slice elements.
     87       void operator-=(const valarray<_Tp>&) const;
     88       ///  Logical xor slice elements with corresponding elements of @a v.
     89       void operator^=(const valarray<_Tp>&) const;
     90       ///  Logical and slice elements with corresponding elements of @a v.
     91       void operator&=(const valarray<_Tp>&) const;
     92       ///  Logical or slice elements with corresponding elements of @a v.
     93       void operator|=(const valarray<_Tp>&) const;
     94       ///  Left shift slice elements by corresponding elements of @a v.
     95       void operator<<=(const valarray<_Tp>&) const;
     96       ///  Right shift slice elements by corresponding elements of @a v.
     97       void operator>>=(const valarray<_Tp>&) const;
     98       ///  Assign all slice elements to @a t.
     99       void operator=(const _Tp&) const;
    100 
    101         //        ~mask_array ();
    102 
    103       template<class _Dom>
    104         void operator=(const _Expr<_Dom,_Tp>&) const;
    105       template<class _Dom>
    106         void operator*=(const _Expr<_Dom,_Tp>&) const;
    107       template<class _Dom>
    108         void operator/=(const _Expr<_Dom,_Tp>&) const;
    109       template<class _Dom>
    110         void operator%=(const _Expr<_Dom,_Tp>&) const;
    111       template<class _Dom>
    112         void operator+=(const _Expr<_Dom,_Tp>&) const;
    113       template<class _Dom>
    114         void operator-=(const _Expr<_Dom,_Tp>&) const;
    115       template<class _Dom>
    116         void operator^=(const _Expr<_Dom,_Tp>&) const;
    117       template<class _Dom>
    118         void operator&=(const _Expr<_Dom,_Tp>&) const;
    119       template<class _Dom>
    120         void operator|=(const _Expr<_Dom,_Tp>&) const;
    121       template<class _Dom>
    122         void operator<<=(const _Expr<_Dom,_Tp>&) const;
    123       template<class _Dom>
    124         void operator>>=(const _Expr<_Dom,_Tp>&) const;
    125 
    126     private:
    127       mask_array(_Array<_Tp>, size_t, _Array<bool>);
    128       friend class valarray<_Tp>;
    129 
    130       const size_t       _M_sz;
    131       const _Array<bool> _M_mask;
    132       const _Array<_Tp>  _M_array;
    133 
    134       // not implemented
    135       mask_array();
    136     };
    137 
    138   template<typename _Tp>
    139     inline mask_array<_Tp>::mask_array(const mask_array<_Tp>& a)
    140     : _M_sz(a._M_sz), _M_mask(a._M_mask), _M_array(a._M_array) {}
    141 
    142   template<typename _Tp>
    143     inline
    144     mask_array<_Tp>::mask_array(_Array<_Tp> __a, size_t __s, _Array<bool> __m)
    145     : _M_sz(__s), _M_mask(__m), _M_array(__a) {}
    146 
    147   template<typename _Tp>
    148     inline mask_array<_Tp>&
    149     mask_array<_Tp>::operator=(const mask_array<_Tp>& __a)
    150     {
    151       std::__valarray_copy(__a._M_array, __a._M_mask,
    152 			   _M_sz, _M_array, _M_mask);
    153       return *this;
    154     }
    155 
    156   template<typename _Tp>
    157     inline void
    158     mask_array<_Tp>::operator=(const _Tp& __t) const
    159     { std::__valarray_fill(_M_array, _M_sz, _M_mask, __t); }
    160 
    161   template<typename _Tp>
    162     inline void
    163     mask_array<_Tp>::operator=(const valarray<_Tp>& __v) const
    164     { std::__valarray_copy(_Array<_Tp>(__v), __v.size(), _M_array, _M_mask); }
    165 
    166   template<typename _Tp>
    167     template<class _Ex>
    168       inline void
    169       mask_array<_Tp>::operator=(const _Expr<_Ex, _Tp>& __e) const
    170       { std::__valarray_copy(__e, __e.size(), _M_array, _M_mask); }
    171 
    172 #undef _DEFINE_VALARRAY_OPERATOR
    173 #define _DEFINE_VALARRAY_OPERATOR(_Op, _Name)				\
    174   template<typename _Tp>						\
    175     inline void								\
    176     mask_array<_Tp>::operator _Op##=(const valarray<_Tp>& __v) const	\
    177     {									\
    178       _Array_augmented_##_Name(_M_array, _M_mask,			\
    179 			       _Array<_Tp>(__v), __v.size());		\
    180     }									\
    181 									\
    182   template<typename _Tp>                                                \
    183     template<class _Dom>			                        \
    184       inline void							\
    185       mask_array<_Tp>::operator _Op##=(const _Expr<_Dom, _Tp>& __e) const\
    186       {									\
    187 	_Array_augmented_##_Name(_M_array, _M_mask, __e, __e.size());   \
    188       }
    189 
    190 _DEFINE_VALARRAY_OPERATOR(*, __multiplies)
    191 _DEFINE_VALARRAY_OPERATOR(/, __divides)
    192 _DEFINE_VALARRAY_OPERATOR(%, __modulus)
    193 _DEFINE_VALARRAY_OPERATOR(+, __plus)
    194 _DEFINE_VALARRAY_OPERATOR(-, __minus)
    195 _DEFINE_VALARRAY_OPERATOR(^, __bitwise_xor)
    196 _DEFINE_VALARRAY_OPERATOR(&, __bitwise_and)
    197 _DEFINE_VALARRAY_OPERATOR(|, __bitwise_or)
    198 _DEFINE_VALARRAY_OPERATOR(<<, __shift_left)
    199 _DEFINE_VALARRAY_OPERATOR(>>, __shift_right)
    200 
    201 #undef _DEFINE_VALARRAY_OPERATOR
    202 
    203   // @} group numeric_arrays
    204 
    205 _GLIBCXX_END_NAMESPACE_VERSION
    206 } // namespace
    207 
    208 #endif /* _MASK_ARRAY_H */
    209