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