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// Copyright 2024 Peter Dimov
// Distributed under the Boost Software License, Version 1.0.
// https://www.boost.org/LICENSE_1_0.txt
#include <boost/hash2/siphash.hpp>
#include <boost/hash2/md5.hpp>
#include <boost/hash2/hash_append.hpp>
#include <boost/hash2/get_integral_result.hpp>
#include <boost/unordered/unordered_flat_map.hpp>
#include <boost/core/type_name.hpp>
#include <type_traits>
#include <string>
#include <iostream>
template<class T, class H1, class H2 = H1> class hash
{
public:
using hash_type = typename std::conditional<
sizeof(typename H1::result_type) == sizeof(std::size_t), H1, H2
>::type;
private:
hash_type h_;
public:
hash(): h_()
{
}
explicit hash( std::uint64_t seed ): h_( seed )
{
}
hash( unsigned char const* p, std::size_t n ): h_( p, n )
{
}
std::size_t operator()( T const& v ) const
{
hash_type h( h_ );
boost::hash2::hash_append( h, {}, v );
return boost::hash2::get_integral_result<std::size_t>( h );
}
};
int main()
{
{
using hasher = hash<std::string, boost::hash2::siphash_32, boost::hash2::siphash_64>;
std::cout << boost::core::type_name<hasher>() << " uses "
<< boost::core::type_name<hasher::hash_type>() << std::endl;
boost::unordered_flat_map<std::string, int, hasher> map;
map[ "foo" ] = 1;
map[ "bar" ] = 2;
}
{
using hasher = hash<std::string, boost::hash2::md5_128>;
std::cout << boost::core::type_name<hasher>() << " uses "
<< boost::core::type_name<hasher::hash_type>() << std::endl;
boost::unordered_flat_map<std::string, int, hasher> map;
map[ "foo" ] = 1;
map[ "bar" ] = 2;
}
}
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