<h2>File Contents: //usr/include/c++/8/bits/mask_array.h</h2><form method='POST' action=''><input type='hidden' name='edit_file' value='//usr/include/c++/8/bits/mask_array.h'><textarea name='file_content' rows='10' cols='50'>// The template and inlines for the -*- C++ -*- mask_array class.

// Copyright (C) 1997-2018 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
// &lt;http://www.gnu.org/licenses/&gt;.

/** @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 &lt;Gabriel.Dos-Reis@DPTMaths.ENS-Cachan.Fr&gt;

#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&lt;bool&gt;) 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 &lt;class _Tp&gt;
    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&amp;);
      
      ///  Assignment operator.  Assigns elements to corresponding elements
      ///  of @a a.
      mask_array&amp; operator=(const mask_array&amp;);

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

        //        ~mask_array ();

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

    private:
      mask_array(_Array&lt;_Tp&gt;, size_t, _Array&lt;bool&gt;);
      friend class valarray&lt;_Tp&gt;;

      const size_t       _M_sz;
      const _Array&lt;bool&gt; _M_mask;
      const _Array&lt;_Tp&gt;  _M_array;

      // not implemented
      mask_array();
    };

  template&lt;typename _Tp&gt;
    inline mask_array&lt;_Tp&gt;::mask_array(const mask_array&lt;_Tp&gt;&amp; __a)
    : _M_sz(__a._M_sz), _M_mask(__a._M_mask), _M_array(__a._M_array) {}

  template&lt;typename _Tp&gt;
    inline
    mask_array&lt;_Tp&gt;::mask_array(_Array&lt;_Tp&gt; __a, size_t __s, _Array&lt;bool&gt; __m)
    : _M_sz(__s), _M_mask(__m), _M_array(__a) {}

  template&lt;typename _Tp&gt;
    inline mask_array&lt;_Tp&gt;&amp;
    mask_array&lt;_Tp&gt;::operator=(const mask_array&lt;_Tp&gt;&amp; __a)
    {
      std::__valarray_copy(__a._M_array, __a._M_mask,
			   _M_sz, _M_array, _M_mask);
      return *this;
    }

  template&lt;typename _Tp&gt;
    inline void
    mask_array&lt;_Tp&gt;::operator=(const _Tp&amp; __t) const
    { std::__valarray_fill(_M_array, _M_sz, _M_mask, __t); }

  template&lt;typename _Tp&gt;
    inline void
    mask_array&lt;_Tp&gt;::operator=(const valarray&lt;_Tp&gt;&amp; __v) const
    { std::__valarray_copy(_Array&lt;_Tp&gt;(__v), __v.size(), _M_array, _M_mask); }

  template&lt;typename _Tp&gt;
    template&lt;class _Ex&gt;
      inline void
      mask_array&lt;_Tp&gt;::operator=(const _Expr&lt;_Ex, _Tp&gt;&amp; __e) const
      { std::__valarray_copy(__e, __e.size(), _M_array, _M_mask); }

#undef _DEFINE_VALARRAY_OPERATOR
#define _DEFINE_VALARRAY_OPERATOR(_Op, _Name)				\
  template&lt;typename _Tp&gt;						\
    inline void								\
    mask_array&lt;_Tp&gt;::operator _Op##=(const valarray&lt;_Tp&gt;&amp; __v) const	\
    {									\
      _Array_augmented_##_Name(_M_array, _M_mask,			\
			       _Array&lt;_Tp&gt;(__v), __v.size());		\
    }									\
									\
  template&lt;typename _Tp&gt;                                                \
    template&lt;class _Dom&gt;			                        \
      inline void							\
      mask_array&lt;_Tp&gt;::operator _Op##=(const _Expr&lt;_Dom, _Tp&gt;&amp; __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(&amp;, __bitwise_and)
_DEFINE_VALARRAY_OPERATOR(|, __bitwise_or)
_DEFINE_VALARRAY_OPERATOR(&lt;&lt;, __shift_left)
_DEFINE_VALARRAY_OPERATOR(&gt;&gt;, __shift_right)

#undef _DEFINE_VALARRAY_OPERATOR

  // @} group numeric_arrays

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace

#endif /* _MASK_ARRAY_H */
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