85 lines
2.1 KiB
C++
85 lines
2.1 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef MOZILLA_AUTO_MAPPABLE_H
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#define MOZILLA_AUTO_MAPPABLE_H
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// Here be dragons.
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#include <functional>
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#include <tuple>
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namespace mozilla {
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template <class T>
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size_t StdHash(const T& t) {
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return std::hash<T>()(t);
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}
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//-
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// From Boost:
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// https://www.boost.org/doc/libs/1_37_0/doc/html/hash/reference.html#boost.hash_combine
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inline size_t HashCombine(size_t seed, const size_t hash) {
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seed ^= hash + 0x9e3779b9 + (seed << 6) + (seed >> 2);
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return seed;
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}
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// -
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namespace detail {
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template <class... Args, size_t... Ids>
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size_t StdHashTupleN(const std::tuple<Args...>& tup,
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const std::index_sequence<Ids...>&) {
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size_t seed = 0;
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for (const auto& hash : {StdHash(std::get<Ids>(tup))...}) {
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seed = HashCombine(seed, hash);
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}
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return seed;
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}
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} // namespace detail
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// -
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template <class T>
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struct StdHashMembers {
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size_t operator()(const T& t) const {
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const auto members = t.Members();
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return StdHash(members);
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}
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};
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// -
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#define MOZ_MIXIN_DERIVE_CMP_OP_BY_MEMBERS(OP, T) \
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bool operator OP(const T& rhs) const { return Members() OP rhs.Members(); }
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#define MOZ_MIXIN_DERIVE_CMP_OPS_BY_MEMBERS(T) \
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MOZ_MIXIN_DERIVE_CMP_OP_BY_MEMBERS(==, T) \
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MOZ_MIXIN_DERIVE_CMP_OP_BY_MEMBERS(!=, T) \
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MOZ_MIXIN_DERIVE_CMP_OP_BY_MEMBERS(<, T) \
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MOZ_MIXIN_DERIVE_CMP_OP_BY_MEMBERS(<=, T) \
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MOZ_MIXIN_DERIVE_CMP_OP_BY_MEMBERS(>, T) \
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MOZ_MIXIN_DERIVE_CMP_OP_BY_MEMBERS(>=, T)
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template <class T>
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struct DeriveCmpOpMembers {
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private:
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auto Members() const { return reinterpret_cast<const T*>(this)->Members(); }
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public:
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MOZ_MIXIN_DERIVE_CMP_OPS_BY_MEMBERS(T)
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};
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} // namespace mozilla
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template <class... Args>
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struct std::hash<std::tuple<Args...>> {
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size_t operator()(const std::tuple<Args...>& t) const {
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return mozilla::detail::StdHashTupleN(
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t, std::make_index_sequence<sizeof...(Args)>());
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}
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};
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#endif // MOZILLA_AUTO_MAPPABLE_H
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