exercise-4-2.hpp

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// ===-- chapter-4/exercise-4-2.hpp ----------------------- -*- C++ -*- --=== //
#ifndef EXERCISE_4_2
#define EXERCISE_4_2
 
#include "chapter-4-undefined_bool.hpp"
 
#include <boost/static_assert.hpp>
#include <boost/mpl/bool.hpp>
 
 
namespace exercise_4_2 {
using namespace chapter4;
 
template <
    typename E1,
    typename E2,
    typename E3 = boost::mpl::false_,
    typename E4 = boost::mpl::false_,
    typename E5 = boost::mpl::false_>
struct logical_or5
    : logical_or5<boost::mpl::bool_<E1::value>, E2, E3, E4, E5> { };
 
template <typename E2, typename E3, typename E4, typename E5>
struct logical_or5<boost::mpl::true_, E2, E3, E4, E5>
{
    static bool const value = true;
};
template <typename E2, typename E3, typename E4, typename E5>
struct logical_or5<boost::mpl::false_, E2, E3, E4, E5>
    : logical_or5<
        boost::mpl::bool_<E2::value>, E2, E3, E4, boost::mpl::false_> { };
 
template <typename E5>
struct logical_or5<
    boost::mpl::false_,
    boost::mpl::false_,
    boost::mpl::false_,
    boost::mpl::false_,
    E5>
{
    static bool const value = E5::value;
};
 
} // namespace exercise_4_2
 
#endif // EXERCISE_4_2