__polymorphic_hasher.hpp

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#pragma once
#if !defined(__XTD_CORE_INTERNAL__)
#error "Do not include this file: Internal use only"
#endif
 
#include "../object.hpp"
#include "../ihashable.hpp"
#include <functional>
#include <type_traits>
 
template<typename key_t>
using __is_hashable__ = std::is_invocable<std::hash<key_t>, const key_t&>;
 
template<typename key_t, typename bool_t>
struct __value_hasher__ {};
 
template<typename key_t>
struct __value_hasher__<key_t, std::true_type> {
  xtd::size operator()(const key_t& key) const {return std::hash<key_t> {}(key);}
};
 
template<typename key_t>
struct __value_hasher__<key_t, std::false_type> {
  xtd::size operator()(const key_t& key) const {
    return std::hash<std::intptr_t> {}(reinterpret_cast<std::intptr_t>(&key));
    //return std::hash<std::string_view>{}(typeid(key).name());
  }
};
 
template<typename key_t, typename bool_t>
struct __object_hasher__ {};
 
template<typename key_t>
struct __object_hasher__<key_t, std::true_type> {
  xtd::size operator()(const key_t& key) const {return static_cast<const xtd::object&>(key).get_hash_code();}
};
 
template<typename key_t>
struct __object_hasher__<key_t, std::false_type> {
  xtd::size operator()(const key_t& key) const {return __value_hasher__<key_t, typename __is_hashable__<key_t>::type> {}(key);}
};
 
template<typename key_t, typename bool_t>
struct __ihashable_hasher__ {};
 
template<typename key_t>
struct __ihashable_hasher__<key_t, std::true_type> {
  xtd::size operator()(const key_t& key) const {return static_cast<const xtd::ihashable&>(key).get_hash_code();}
};
 
template<typename key_t>
struct __ihashable_hasher__<key_t, std::false_type> {
  xtd::size operator()(const key_t& key) const {return __object_hasher__<key_t, typename std::is_base_of<xtd::object, key_t>::type> {}(key);}
};
 
template<typename key_t, typename bool_t>
struct __polymorphic_hasher__ {};
 
template<typename key_t>
struct __polymorphic_hasher__<key_t, std::true_type> {
  xtd::size operator()(const key_t& key) const {return __ihashable_hasher__<key_t, typename std::is_base_of<xtd::ihashable, key_t>::type> {}(key);}
};
 
template<typename key_t>
struct __polymorphic_hasher__<key_t, std::false_type> {
  xtd::size operator()(const key_t& key) const {return __value_hasher__<key_t, typename __is_hashable__<key_t>::type> {}(key);}
};