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update internal detect code, add is_explicitly_convertible and is_complete (#316)

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This commit is contained in:
Hans Dembinski
2021-04-23 14:58:54 +02:00
committed by GitHub
parent 7902c851b2
commit 5d671b4ffc
2 changed files with 76 additions and 40 deletions
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84
include/boost/histogram/detail/detect.hpp
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@@ -27,33 +27,40 @@ namespace boost {
namespace histogram {
namespace detail {
#define BOOST_HISTOGRAM_DETAIL_DETECT(name, cond) \
template <class U> \
struct name##_impl { \
typedef char yes[1]; \
typedef char no[2]; \
template <class T> \
static yes& test(T& t, decltype(cond, 0)); \
template <class T> \
static no& test(T&, float); \
using type = \
std::integral_constant<bool, (sizeof(test(std::declval<U&>(), 0)) == 1)>; \
}; \
template <class T> \
template <class...>
using void_t = void;
struct detect_base {
template <class T>
static T&& val();
template <class T>
static T& ref();
template <class T>
static T const& cref();
};
#define BOOST_HISTOGRAM_DETAIL_DETECT(name, cond) \
template <class U> \
struct name##_impl : detect_base { \
template <class T> \
static mp11::mp_true test(T& t, decltype(cond, 0)); \
template <class T> \
static mp11::mp_false test(T&, float); \
using type = decltype(test<U>(ref<U>(), 0)); \
}; \
template <class T> \
using name = typename name##_impl<T>::type
#define BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(name, cond) \
template <class V, class W> \
struct name##_impl { \
typedef char yes[1]; \
typedef char no[2]; \
template <class T, class U> \
static yes& test(decltype(cond, 0)); \
template <class, class> \
static no& test(float); \
using type = std::integral_constant<bool, (sizeof(test<V, W>(0)) == 1)>; \
}; \
template <class T, class U = T> \
#define BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(name, cond) \
template <class V, class W> \
struct name##_impl : detect_base { \
template <class T, class U> \
static mp11::mp_true test(T& t, U& u, decltype(cond, 0)); \
template <class T, class U> \
static mp11::mp_false test(T&, U&, float); \
using type = decltype(test<V, W>(ref<V>(), ref<W>(), 0)); \
}; \
template <class T, class U = T> \
using name = typename name##_impl<T, U>::type
// reset has overloads, trying to get pmf in this case always fails
@@ -61,9 +68,7 @@ BOOST_HISTOGRAM_DETAIL_DETECT(has_method_reset, t.reset(0));
BOOST_HISTOGRAM_DETAIL_DETECT(is_indexable, t[0]);
BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(
is_transform,
(std::declval<T&>().inverse(std::declval<T&>().forward(std::declval<U>()))));
BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(is_transform, (t.inverse(t.forward(u))));
BOOST_HISTOGRAM_DETAIL_DETECT(is_indexable_container,
(t[0], t.size(), std::begin(t), std::end(t)));
@@ -90,26 +95,25 @@ BOOST_HISTOGRAM_DETAIL_DETECT(is_streamable, (std::declval<std::ostream&>() << t
BOOST_HISTOGRAM_DETAIL_DETECT(has_operator_preincrement, ++t);
BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(has_operator_equal, (std::declval<const T&>() ==
std::declval<const U&>()));
BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(has_operator_equal, (cref<T>() == u));
BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(has_operator_radd,
(std::declval<T&>() += std::declval<U>()));
BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(has_operator_radd, (t += u));
BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(has_operator_rsub,
(std::declval<T&>() -= std::declval<U>()));
BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(has_operator_rsub, (t -= u));
BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(has_operator_rmul,
(std::declval<T&>() *= std::declval<U>()));
BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(has_operator_rmul, (t *= u));
BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(has_operator_rdiv,
(std::declval<T&>() /= std::declval<U>()));
BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(has_operator_rdiv, (t /= u));
BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(
has_method_eq, (std::declval<const T&>().operator==(std::declval<const U&>())));
BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(has_method_eq, (cref<T>().operator==(u)));
BOOST_HISTOGRAM_DETAIL_DETECT(has_threading_support, (T::has_threading_support));
// stronger form of std::is_convertible that works with explicit operator T and ctors
BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(is_explicitly_convertible, static_cast<U>(t));
BOOST_HISTOGRAM_DETAIL_DETECT(is_complete, sizeof(T));
template <class T>
using is_storage = mp11::mp_and<is_indexable_container<T>, has_method_reset<T>,
has_threading_support<T>>;

32
test/detail_detect_test.cpp
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@@ -197,5 +197,37 @@ int main() {
BOOST_TEST_TRAIT_TRUE((has_operator_radd<B&, const B&>));
}
// is_explicitly_convertible
{
struct A {};
struct B {
operator A() { return A{}; }
};
struct C {
explicit operator A();
};
struct D {
D(A);
};
struct E {
explicit E(A);
};
BOOST_TEST_TRAIT_TRUE((is_explicitly_convertible<A, A>));
BOOST_TEST_TRAIT_FALSE((is_explicitly_convertible<A, B>));
BOOST_TEST_TRAIT_TRUE((is_explicitly_convertible<B, A>));
BOOST_TEST_TRAIT_TRUE((is_explicitly_convertible<C, A>));
BOOST_TEST_TRAIT_TRUE((is_explicitly_convertible<A, D>));
BOOST_TEST_TRAIT_TRUE((is_explicitly_convertible<A, E>));
}
// is_complete
{
struct A;
struct B {};
BOOST_TEST_TRAIT_FALSE((is_complete<A>));
BOOST_TEST_TRAIT_TRUE((is_complete<B>));
}
return boost::report_errors();
}