1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
|
// 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/hash_append.hpp>
#include <boost/hash2/get_integral_result.hpp>
#include <boost/unordered/unordered_flat_map.hpp>
#include <string>
template<class T, class H> class hash
{
private:
H 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
{
H 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_64>;
{
boost::unordered_flat_map<std::string, int, hasher> map;
map[ "foo" ] = 1;
map[ "bar" ] = 2;
}
{
std::uint64_t seed = 0x0102030405060708ull;
boost::unordered_flat_map<std::string, int, hasher> map( 0, hasher( seed ) );
map[ "foo" ] = 1;
map[ "bar" ] = 2;
}
{
unsigned char const seed[ 16 ] =
{
0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x10
};
boost::unordered_flat_map<std::string, int, hasher> map( 0, hasher(seed, sizeof(seed)) );
map[ "foo" ] = 1;
map[ "bar" ] = 2;
}
}
|
