// Copyright 2015-2019 Hans Dembinski
//
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt
// or copy at http://www.boost.org/LICENSE_1_0.txt)
#ifndef BOOST_HISTOGRAM_DETAIL_DETECT_HPP
#define BOOST_HISTOGRAM_DETAIL_DETECT_HPP
#include <boost/histogram/fwd.hpp>
#include <boost/mp11/function.hpp> // mp_and, mp_or
#include <boost/mp11/integral.hpp> // mp_not
#include <boost/mp11/list.hpp> // mp_first
#include <iterator>
#include <tuple>
#include <type_traits>
// forward declaration
namespace boost {
namespace variant2 {
template <class...>
class variant;
} // namespace variant2
} // namespace boost
namespace boost {
namespace histogram {
namespace detail {
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 : 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
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, (t.inverse(t.forward(u))));
BOOST_HISTOGRAM_DETAIL_DETECT(is_indexable_container,
(t[0], t.size(), std::begin(t), std::end(t)));
BOOST_HISTOGRAM_DETAIL_DETECT(is_vector_like,
(t[0], t.size(), t.resize(0), std::begin(t), std::end(t)));
BOOST_HISTOGRAM_DETAIL_DETECT(is_array_like, (t[0], t.size(), std::tuple_size<T>::value,
std::begin(t), std::end(t)));
BOOST_HISTOGRAM_DETAIL_DETECT(is_map_like, ((typename T::key_type*)nullptr,
(typename T::mapped_type*)nullptr,
std::begin(t), std::end(t)));
// ok: is_axis is false for axis::variant, because T::index is templated
BOOST_HISTOGRAM_DETAIL_DETECT(is_axis, (t.size(), &T::index));
BOOST_HISTOGRAM_DETAIL_DETECT(is_iterable, (std::begin(t), std::end(t)));
BOOST_HISTOGRAM_DETAIL_DETECT(is_iterator,
(typename std::iterator_traits<T>::iterator_category{}));
BOOST_HISTOGRAM_DETAIL_DETECT(is_streamable, (std::declval<std::ostream&>() << t));
BOOST_HISTOGRAM_DETAIL_DETECT(is_allocator, (&T::allocate, &T::deallocate));
BOOST_HISTOGRAM_DETAIL_DETECT(has_operator_preincrement, ++t);
BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(has_operator_equal, (cref<T>() == u));
BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(has_operator_radd, (t += u));
BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(has_operator_rsub, (t -= u));
BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(has_operator_rmul, (t *= u));
BOOST_HISTOGRAM_DETAIL_DETECT_BINARY(has_operator_rdiv, (t /= 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>>;
template <class T>
using is_adaptible =
mp11::mp_and<mp11::mp_not<is_storage<T>>,
mp11::mp_or<is_vector_like<T>, is_array_like<T>, is_map_like<T>>>;
template <class T>
struct is_tuple_impl : std::false_type {};
template <class... Ts>
struct is_tuple_impl<std::tuple<Ts...>> : std::true_type {};
template <class T>
using is_tuple = typename is_tuple_impl<T>::type;
template <class T>
struct is_variant_impl : std::false_type {};
template <class... Ts>
struct is_variant_impl<boost::variant2::variant<Ts...>> : std::true_type {};
template <class T>
using is_variant = typename is_variant_impl<T>::type;
template <class T>
struct is_axis_variant_impl : std::false_type {};
template <class... Ts>
struct is_axis_variant_impl<axis::variant<Ts...>> : std::true_type {};
template <class T>
using is_axis_variant = typename is_axis_variant_impl<T>::type;
template <class T>
using is_any_axis = mp11::mp_or<is_axis<T>, is_axis_variant<T>>;
template <class T>
using is_sequence_of_axis = mp11::mp_and<is_iterable<T>, is_axis<mp11::mp_first<T>>>;
template <class T>
using is_sequence_of_axis_variant =
mp11::mp_and<is_iterable<T>, is_axis_variant<mp11::mp_first<T>>>;
template <class T>
using is_sequence_of_any_axis =
mp11::mp_and<is_iterable<T>, is_any_axis<mp11::mp_first<T>>>;
// Poor-mans concept checks.
// These must be structs not aliases, so their names pop up in compiler errors.
template <class T, class = std::enable_if_t<is_storage<std::decay_t<T>>::value>>
struct requires_storage {};
template <class T, class _ = std::decay_t<T>,
class = std::enable_if_t<(is_storage<_>::value || is_adaptible<_>::value)>>
struct requires_storage_or_adaptible {};
template <class T, class = std::enable_if_t<is_iterator<std::decay_t<T>>::value>>
struct requires_iterator {};
template <class T, class = std::enable_if_t<
is_iterable<std::remove_cv_t<std::remove_reference_t<T>>>::value>>
struct requires_iterable {};
template <class T, class = std::enable_if_t<is_axis<std::decay_t<T>>::value>>
struct requires_axis {};
template <class T, class = std::enable_if_t<is_any_axis<std::decay_t<T>>::value>>
struct requires_any_axis {};
template <class T, class = std::enable_if_t<is_sequence_of_axis<std::decay_t<T>>::value>>
struct requires_sequence_of_axis {};
template <class T,
class = std::enable_if_t<is_sequence_of_axis_variant<std::decay_t<T>>::value>>
struct requires_sequence_of_axis_variant {};
template <class T,
class = std::enable_if_t<is_sequence_of_any_axis<std::decay_t<T>>::value>>
struct requires_sequence_of_any_axis {};
template <class T,
class = std::enable_if_t<is_any_axis<mp11::mp_first<std::decay_t<T>>>::value>>
struct requires_axes {};
template <class T, class U,
class = std::enable_if_t<is_transform<std::decay_t<T>, U>::value>>
struct requires_transform {};
template <class T, class = std::enable_if_t<is_allocator<std::decay_t<T>>::value>>
struct requires_allocator {};
} // namespace detail
} // namespace histogram
} // namespace boost
#endif