text: // The template and inlines for the -*- C++ -*- mask_array class.
  
  // Copyright (C) 1997-2014 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 3, 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.
  
  // Under Section 7 of GPL version 3, you are granted additional
  // permissions described in the GCC Runtime Library Exception, version
  // 3.1, as published by the Free Software Foundation.
  
  // You should have received a copy of the GNU General Public License and
  // a copy of the GCC Runtime Library Exception along with this program;
  // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  // <http://www.gnu.org/licenses/>.
  
  /** @file bits/mask_array.h
   *  This is an internal header file, included by other library headers.
   *  Do not attempt to use it directly. @headername{valarray}
   */
  
  // Written by Gabriel Dos Reis <Gabriel.Dos-Reis@DPTMaths.ENS-Cachan.Fr>
  
  #ifndef _MASK_ARRAY_H
  #define _MASK_ARRAY_H 1
  
  #pragma GCC system_header
  
  namespace std _GLIBCXX_VISIBILITY(default)
  {
  _GLIBCXX_BEGIN_NAMESPACE_VERSION
  
    /**
     * @addtogroup numeric_arrays
     * @{
     */
  
    /**
     *  @brief  Reference to selected subset of an array.
     *
     *  A mask_array is a reference to the actual elements of an array specified
     *  by a bitmask in the form of an array of bool.  The way to get a
     *  mask_array is to call operator[](valarray<bool>) on a valarray.  The
     *  returned mask_array then permits carrying operations out on the
     *  referenced subset of elements in the original valarray.
     *
     *  For example, if a mask_array is obtained using the array (false, true,
     *  false, true) as an argument, the mask array has two elements referring
     *  to array[1] and array[3] in the underlying array.
     *
     *  @param  Tp  Element type.
     */
    template <class _Tp>
      class mask_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.
        mask_array (const mask_array&);
        
        ///  Assignment operator.  Assigns elements to corresponding elements
        ///  of @a a.
        mask_array& operator=(const mask_array&);
  
        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;
  
          //        ~mask_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:
        mask_array(_Array<_Tp>, size_t, _Array<bool>);
        friend class valarray<_Tp>;
  
        const size_t       _M_sz;
        const _Array<bool> _M_mask;
        const _Array<_Tp>  _M_array;
  
        // not implemented
        mask_array();
      };
  
    template<typename _Tp>
      inline mask_array<_Tp>::mask_array(const mask_array<_Tp>& a)
      : _M_sz(a._M_sz), _M_mask(a._M_mask), _M_array(a._M_array) {}
  
    template<typename _Tp>
      inline
      mask_array<_Tp>::mask_array(_Array<_Tp> __a, size_t __s, _Array<bool> __m)
      : _M_sz(__s), _M_mask(__m), _M_array(__a) {}
  
    template<typename _Tp>
      inline mask_array<_Tp>&
      mask_array<_Tp>::operator=(const mask_array<_Tp>& __a)
      {
        std::__valarray_copy(__a._M_array, __a._M_mask,
  			   _M_sz, _M_array, _M_mask);
        return *this;
      }
  
    template<typename _Tp>
      inline void
      mask_array<_Tp>::operator=(const _Tp& __t) const
      { std::__valarray_fill(_M_array, _M_sz, _M_mask, __t); }
  
    template<typename _Tp>
      inline void
      mask_array<_Tp>::operator=(const valarray<_Tp>& __v) const
      { std::__valarray_copy(_Array<_Tp>(__v), __v.size(), _M_array, _M_mask); }
  
    template<typename _Tp>
      template<class _Ex>
        inline void
        mask_array<_Tp>::operator=(const _Expr<_Ex, _Tp>& __e) const
        { std::__valarray_copy(__e, __e.size(), _M_array, _M_mask); }
  
  #undef _DEFINE_VALARRAY_OPERATOR
  #define _DEFINE_VALARRAY_OPERATOR(_Op, _Name)				\
    template<typename _Tp>						\
      inline void								\
      mask_array<_Tp>::operator _Op##=(const valarray<_Tp>& __v) const	\
      {									\
        _Array_augmented_##_Name(_M_array, _M_mask,			\
  			       _Array<_Tp>(__v), __v.size());		\
      }									\
  									\
    template<typename _Tp>                                                \
      template<class _Dom>			                        \
        inline void							\
        mask_array<_Tp>::operator _Op##=(const _Expr<_Dom, _Tp>& __e) const\
        {									\
  	_Array_augmented_##_Name(_M_array, _M_mask, __e, __e.size());   \
        }
  
  _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
  
    // @} group numeric_arrays
  
  _GLIBCXX_END_NAMESPACE_VERSION
  } // namespace
  
  #endif /* _MASK_ARRAY_H */
  