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3rdparty/boost_1_81_0/libs/hana/test/repeat.cpp 1.27 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/fwd/concept/integral_constant.hpp>
  #include <boost/hana/repeat.hpp>
  namespace hana = boost::hana;
  
  
  //////////////////////////////////////////////////////////////////////////////
  // Define a simple model of IntegralConstant for use below
  template <int i>
  struct constant {
      static constexpr int value = i;
      using value_type = int;
  };
  
  namespace boost { namespace hana {
      template <int i>
      struct IntegralConstant<constant<i>> {
          static constexpr bool value = true;
      };
  
      // definition of `to<>` omitted
  }}
  //////////////////////////////////////////////////////////////////////////////
  
  void function() { }
  
  int main() {
      int counter = 0;
      hana::repeat(constant<3>{}, [&] { ++counter; });
      BOOST_HANA_RUNTIME_CHECK(counter == 3);
  
      // Try with a normal function.
      hana::repeat(constant<3>{}, function);
  
      // Try with a function pointer.
      hana::repeat(constant<3>{}, static_cast<void(*)()>(function));
  
      // Make sure we don't read from a non-constexpr variable.
      constant<3> three{};
      hana::repeat(three, []{});
  }