MapUtils.h

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/*
 * This file is part of the TrinityCore Project. See AUTHORS file for Copyright information
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program. If not, see <http://www.gnu.org/licenses/>.
 */
 
#ifndef TRINITYCORE_MAP_UTILS_H
#define TRINITYCORE_MAP_UTILS_H
 
#include <memory>       // std::to_address, std::addressof
#include <type_traits>
 
namespace Trinity::Containers
{
template <typename M>
concept Map = requires (M)
{
    typename M::key_type;
    typename M::mapped_type;
};
 
template <Map M>
inline auto MapGetValuePtr(M& map, typename M::key_type const& key)
{
    using mapped_type = typename M::mapped_type;
 
    auto itr = map.find(key);
    if constexpr (std::is_pointer_v<mapped_type>)
        return itr != map.end() ? itr->second : nullptr;                        // raw pointer
    else if constexpr (requires(mapped_type const& p) { p.operator->(); })
    {
        // smart pointers
        if constexpr (std::is_copy_constructible_v<mapped_type>)
            return itr != map.end() ? itr->second : nullptr;                    // copyable (like shared_ptr)
        else
            return itr != map.end() ? std::to_address(itr->second) : nullptr;   // non-copyable unique_ptr like, unwrap it to raw pointer
    }
    else
        return itr != map.end() ? std::addressof(itr->second) : nullptr;        // value
}
 
template <Map M>
void MultimapErasePair(M& multimap, typename M::key_type const& key, typename M::mapped_type const& value)
{
    auto range = multimap.equal_range(key);
    for (auto itr = range.first; itr != range.second;)
    {
        if (itr->second == value)
            itr = multimap.erase(itr);
        else
            ++itr;
    }
}
 
inline constexpr auto MapKey = []<typename Pair>(Pair&& pair) constexpr -> decltype(auto) { return (std::forward<Pair>(pair).first); /*Parentheses required for decltype(auto) to deduce a reference*/ };
 
inline constexpr auto MapValue = []<typename Pair>(Pair&& pair) constexpr -> decltype(auto) { return (std::forward<Pair>(pair).second); /*Parentheses required for decltype(auto) to deduce a reference*/
};
}
#endif // TRINITYCORE_MAP_UTILS_H