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3rdparty/boost_1_81_0/libs/hana/example/group.cpp 1.84 KB
73ef4ff3   Hu Chunming   提交三方库
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  // Copyright Louis Dionne 2013-2022
  // Distributed under the Boost Software License, Version 1.0.
  // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
  
  #include <boost/hana/assert.hpp>
  #include <boost/hana/comparing.hpp>
  #include <boost/hana/equal.hpp>
  #include <boost/hana/group.hpp>
  #include <boost/hana/integral_constant.hpp>
  #include <boost/hana/length.hpp>
  #include <boost/hana/range.hpp>
  #include <boost/hana/tuple.hpp>
  #include <boost/hana/type.hpp>
  namespace hana = boost::hana;
  
  
  // group without a predicate
  BOOST_HANA_CONSTANT_CHECK(
      hana::group(hana::make_tuple(hana::int_c<1>, hana::long_c<1>, hana::type_c<int>, hana::char_c<'x'>, hana::char_c<'x'>))
          == hana::make_tuple(
              hana::make_tuple(hana::int_c<1>, hana::long_c<1>),
              hana::make_tuple(hana::type_c<int>),
              hana::make_tuple(hana::char_c<'x'>, hana::char_c<'x'>)
          )
  );
  
  
  // group with a predicate
  constexpr auto tuples = hana::make_tuple(
      hana::range_c<int, 0, 1>,
      hana::range_c<int, 0, 2>,
      hana::range_c<int, 1, 3>,
      hana::range_c<int, 2, 6>
  );
  
  BOOST_HANA_CONSTANT_CHECK(
      hana::group(tuples, hana::comparing(hana::length))
          == hana::make_tuple(
              hana::make_tuple(
                  hana::range_c<int, 0, 1>
              ),
              hana::make_tuple(
                  hana::range_c<int, 0, 2>,
                  hana::range_c<int, 1, 3>
              ),
              hana::make_tuple(
                  hana::range_c<int, 2, 6>
              )
          )
  );
  
  
  // group.by is syntactic sugar
  static_assert(
      hana::group.by(hana::comparing(hana::typeid_),
                     hana::make_tuple(1, 2, 3, 'x', 'y', 4.4, 5.5))
          == hana::make_tuple(
              hana::make_tuple(1, 2, 3),
              hana::make_tuple('x', 'y'),
              hana::make_tuple(4.4, 5.5)
          )
  , "");
  
  int main() { }