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No longer use fold expressions for mp_count to avoid compiler limits

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Peter Dimov
2021-03-22 18:37:46 +02:00
parent b6451c4ae4
commit 0348adbed9
1 changed files with 16 additions and 2 deletions
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18
include/boost/mp11/detail/mp_count.hpp
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@ -43,11 +43,25 @@ constexpr std::size_t cx_plus(T1 t1, T2 t2, T3 t3, T4 t4, T5 t5, T6 t6, T7 t7, T
template<class L, class V> struct mp_count_impl;
#if defined( BOOST_MP11_HAS_FOLD_EXPRESSIONS ) && !BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, < 1930 )
#if defined( BOOST_MP11_HAS_CXX14_CONSTEXPR )
template<class V, class... T> constexpr std::size_t cx_count()
{
constexpr bool a[] = { false, std::is_same<T, V>::value... };
std::size_t r = 0;
for( std::size_t i = 0; i < sizeof...(T); ++i )
{
r += a[ i+1 ];
}
return r;
}
template<template<class...> class L, class... T, class V> struct mp_count_impl<L<T...>, V>
{
using type = mp_size_t<(std::is_same<T, V>::value + ... + 0)>;
using type = mp_size_t<cx_count<V, T...>()>;
};
#elif !defined( BOOST_MP11_NO_CONSTEXPR )