boost/pfr/detail/functional.hpp
// Copyright (c) 2016-2024 Antony Polukhin
//
// 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_PFR_DETAIL_FUNCTIONAL_HPP
#define BOOST_PFR_DETAIL_FUNCTIONAL_HPP
#pragma once
#include <boost/pfr/detail/config.hpp>
#include <functional>
#include <cstdint>
#include <boost/pfr/detail/sequence_tuple.hpp>
namespace boost { namespace pfr { namespace detail {
template <std::size_t I, std::size_t N>
struct equal_impl {
template <class T, class U>
constexpr static bool cmp(const T& v1, const U& v2) noexcept {
return ::boost::pfr::detail::sequence_tuple::get<I>(v1) == ::boost::pfr::detail::sequence_tuple::get<I>(v2)
&& equal_impl<I + 1, N>::cmp(v1, v2);
}
};
template <std::size_t N>
struct equal_impl<N, N> {
template <class T, class U>
constexpr static bool cmp(const T&, const U&) noexcept {
return T::size_v == U::size_v;
}
};
template <std::size_t I, std::size_t N>
struct not_equal_impl {
template <class T, class U>
constexpr static bool cmp(const T& v1, const U& v2) noexcept {
return ::boost::pfr::detail::sequence_tuple::get<I>(v1) != ::boost::pfr::detail::sequence_tuple::get<I>(v2)
|| not_equal_impl<I + 1, N>::cmp(v1, v2);
}
};
template <std::size_t N>
struct not_equal_impl<N, N> {
template <class T, class U>
constexpr static bool cmp(const T&, const U&) noexcept {
return T::size_v != U::size_v;
}
};
template <std::size_t I, std::size_t N>
struct less_impl {
template <class T, class U>
constexpr static bool cmp(const T& v1, const U& v2) noexcept {
return sequence_tuple::get<I>(v1) < sequence_tuple::get<I>(v2)
|| (sequence_tuple::get<I>(v1) == sequence_tuple::get<I>(v2) && less_impl<I + 1, N>::cmp(v1, v2));
}
};
template <std::size_t N>
struct less_impl<N, N> {
template <class T, class U>
constexpr static bool cmp(const T&, const U&) noexcept {
return T::size_v < U::size_v;
}
};
template <std::size_t I, std::size_t N>
struct less_equal_impl {
template <class T, class U>
constexpr static bool cmp(const T& v1, const U& v2) noexcept {
return sequence_tuple::get<I>(v1) < sequence_tuple::get<I>(v2)
|| (sequence_tuple::get<I>(v1) == sequence_tuple::get<I>(v2) && less_equal_impl<I + 1, N>::cmp(v1, v2));
}
};
template <std::size_t N>
struct less_equal_impl<N, N> {
template <class T, class U>
constexpr static bool cmp(const T&, const U&) noexcept {
return T::size_v <= U::size_v;
}
};
template <std::size_t I, std::size_t N>
struct greater_impl {
template <class T, class U>
constexpr static bool cmp(const T& v1, const U& v2) noexcept {
return sequence_tuple::get<I>(v1) > sequence_tuple::get<I>(v2)
|| (sequence_tuple::get<I>(v1) == sequence_tuple::get<I>(v2) && greater_impl<I + 1, N>::cmp(v1, v2));
}
};
template <std::size_t N>
struct greater_impl<N, N> {
template <class T, class U>
constexpr static bool cmp(const T&, const U&) noexcept {
return T::size_v > U::size_v;
}
};
template <std::size_t I, std::size_t N>
struct greater_equal_impl {
template <class T, class U>
constexpr static bool cmp(const T& v1, const U& v2) noexcept {
return sequence_tuple::get<I>(v1) > sequence_tuple::get<I>(v2)
|| (sequence_tuple::get<I>(v1) == sequence_tuple::get<I>(v2) && greater_equal_impl<I + 1, N>::cmp(v1, v2));
}
};
template <std::size_t N>
struct greater_equal_impl<N, N> {
template <class T, class U>
constexpr static bool cmp(const T&, const U&) noexcept {
return T::size_v >= U::size_v;
}
};
// Hash combine functions copied from Boost.ContainerHash
// https://github.com/boostorg/container_hash/blob/171c012d4723c5e93cc7cffe42919afdf8b27dfa/include/boost/container_hash/hash.hpp#L311
// that is based on Peter Dimov's proposal
// http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2005/n1756.pdf
// issue 6.18.
//
// This also contains public domain code from MurmurHash. From the
// MurmurHash header:
//
// MurmurHash3 was written by Austin Appleby, and is placed in the public
// domain. The author hereby disclaims copyright to this source code.
template <typename SizeT>
constexpr void hash_combine(SizeT& seed, SizeT value) noexcept {
seed ^= value + 0x9e3779b9 + (seed<<6) + (seed>>2);
}
constexpr auto rotl(std::uint32_t x, std::uint32_t r) noexcept {
return (x << r) | (x >> (32 - r));
}
constexpr void hash_combine(std::uint32_t& h1, std::uint32_t k1) noexcept {
const std::uint32_t c1 = 0xcc9e2d51;
const std::uint32_t c2 = 0x1b873593;
k1 *= c1;
k1 = detail::rotl(k1,15);
k1 *= c2;
h1 ^= k1;
h1 = detail::rotl(h1,13);
h1 = h1*5+0xe6546b64;
}
#if defined(INT64_MIN) && defined(UINT64_MAX)
constexpr void hash_combine(std::uint64_t& h, std::uint64_t k) noexcept {
const std::uint64_t m = 0xc6a4a7935bd1e995ULL;
const int r = 47;
k *= m;
k ^= k >> r;
k *= m;
h ^= k;
h *= m;
// Completely arbitrary number, to prevent 0's
// from hashing to 0.
h += 0xe6546b64;
}
#endif
template <typename T>
auto compute_hash(const T& value, long /*priority*/)
-> decltype(std::hash<T>()(value))
{
return std::hash<T>()(value);
}
template <typename T>
std::size_t compute_hash(const T& /*value*/, int /*priority*/) {
static_assert(sizeof(T) && false, "====================> Boost.PFR: std::hash not specialized for type T");
return 0;
}
template <std::size_t I, std::size_t N>
struct hash_impl {
template <class T>
constexpr static std::size_t compute(const T& val) noexcept {
std::size_t h = detail::compute_hash( ::boost::pfr::detail::sequence_tuple::get<I>(val), 1L );
detail::hash_combine(h, hash_impl<I + 1, N>::compute(val) );
return h;
}
};
template <std::size_t N>
struct hash_impl<N, N> {
template <class T>
constexpr static std::size_t compute(const T&) noexcept {
return 0;
}
};
///////////////////// Define min_element and to avoid inclusion of <algorithm>
constexpr std::size_t min_size(std::size_t x, std::size_t y) noexcept {
return x < y ? x : y;
}
template <template <std::size_t, std::size_t> class Visitor, class T, class U>
constexpr bool binary_visit(const T& x, const U& y) {
constexpr std::size_t fields_count_lhs = detail::fields_count<std::remove_reference_t<T>>();
constexpr std::size_t fields_count_rhs = detail::fields_count<std::remove_reference_t<U>>();
constexpr std::size_t fields_count_min = detail::min_size(fields_count_lhs, fields_count_rhs);
typedef Visitor<0, fields_count_min> visitor_t;
#if BOOST_PFR_USE_CPP17 || BOOST_PFR_USE_LOOPHOLE
return visitor_t::cmp(detail::tie_as_tuple(x), detail::tie_as_tuple(y));
#else
bool result = true;
::boost::pfr::detail::for_each_field_dispatcher(
x,
[&result, &y](const auto& lhs) {
constexpr std::size_t fields_count_rhs_ = detail::fields_count<std::remove_reference_t<U>>();
::boost::pfr::detail::for_each_field_dispatcher(
y,
[&result, &lhs](const auto& rhs) {
result = visitor_t::cmp(lhs, rhs);
},
detail::make_index_sequence<fields_count_rhs_>{}
);
},
detail::make_index_sequence<fields_count_lhs>{}
);
return result;
#endif
}
}}} // namespace boost::pfr::detail
#endif // BOOST_PFR_DETAIL_FUNCTIONAL_HPP