115 lines
3.6 KiB
C++
115 lines
3.6 KiB
C++
/*!
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@file
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Defines `boost::hana::hash`.
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@copyright Jason Rice 2016
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
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*/
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#ifndef BOOST_HANA_HASH_HPP
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#define BOOST_HANA_HASH_HPP
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#include <boost/hana/fwd/hash.hpp>
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#include <boost/hana/concept/hashable.hpp>
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#include <boost/hana/concept/integral_constant.hpp>
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#include <boost/hana/config.hpp>
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#include <boost/hana/core/dispatch.hpp>
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#include <boost/hana/fwd/integral_constant.hpp>
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#include <boost/hana/type.hpp>
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#include <type_traits>
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BOOST_HANA_NAMESPACE_BEGIN
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//! @cond
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template <typename X>
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constexpr auto hash_t::operator()(X const& x) const {
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using Tag = typename hana::tag_of<X>::type;
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using Hash = BOOST_HANA_DISPATCH_IF(hash_impl<Tag>,
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hana::Hashable<Tag>::value
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);
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#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
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static_assert(hana::Hashable<Tag>::value,
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"hana::hash(x) requires 'x' to be Hashable");
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#endif
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return Hash::apply(x);
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}
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//! @endcond
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template <typename Tag, bool condition>
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struct hash_impl<Tag, when<condition>> : default_ {
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template <typename X>
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static constexpr auto apply(X const&) = delete;
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};
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namespace detail {
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template <typename T, typename = void>
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struct hash_integral_helper;
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template <typename Member, typename T>
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struct hash_integral_helper<Member T::*> {
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template <typename X>
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static constexpr auto apply(X const&) {
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return hana::type_c<hana::integral_constant<Member T::*, X::value>>;
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}
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};
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template <typename T>
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struct hash_integral_helper<T,
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typename std::enable_if<std::is_signed<T>::value>::type
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> {
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template <typename X>
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static constexpr auto apply(X const&) {
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constexpr signed long long x = X::value;
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return hana::type_c<hana::integral_constant<signed long long, x>>;
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}
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};
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template <typename T>
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struct hash_integral_helper<T,
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typename std::enable_if<std::is_unsigned<T>::value>::type
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> {
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template <typename X>
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static constexpr auto apply(X const&) {
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constexpr unsigned long long x = X::value;
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return hana::type_c<hana::integral_constant<unsigned long long, x>>;
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}
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};
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template <>
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struct hash_integral_helper<bool> {
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template <typename X>
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static constexpr auto apply(X const&) {
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return hana::type_c<hana::integral_constant<bool, X::value>>;
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}
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};
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template <>
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struct hash_integral_helper<char> {
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template <typename X>
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static constexpr auto apply(X const&) {
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using T = std::conditional<std::is_signed<char>::value,
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signed long long, unsigned long long
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>::type;
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constexpr T x = X::value;
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return hana::type_c<hana::integral_constant<T, x>>;
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}
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};
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}
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template <typename Tag>
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struct hash_impl<Tag, when<hana::IntegralConstant<Tag>::value>> {
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template <typename X>
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static constexpr auto apply(X const& x) {
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using T = typename std::remove_cv<decltype(X::value)>::type;
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return detail::hash_integral_helper<T>::apply(x);
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}
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};
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BOOST_HANA_NAMESPACE_END
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#endif // !BOOST_HANA_HASH_HPP
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