1 //-----------------------------------------------------------------------------
2 // boost variant/detail/hash_variant.hpp header file
3 // See http://www.boost.org for updates, documentation, and revision history.
4 //-----------------------------------------------------------------------------
5 //
6 // Copyright (c) 2011-2021 Antony Polukhin
7 //
8 // Distributed under the Boost Software License, Version 1.0. (See
9 // accompanying file LICENSE_1_0.txt or copy at
10 // http://www.boost.org/LICENSE_1_0.txt)
11 
12 
13 #ifndef BOOST_HASH_VARIANT_FUNCTION_HPP
14 #define BOOST_HASH_VARIANT_FUNCTION_HPP
15 
16 #if defined(_MSC_VER)
17 # pragma once
18 #endif
19 
20 #include <boost/variant/variant_fwd.hpp>
21 #include <boost/variant/static_visitor.hpp>
22 #include <boost/variant/apply_visitor.hpp>
23 #include <boost/functional/hash_fwd.hpp>
24 
25 namespace boost {
26 
27     namespace detail { namespace variant {
28         struct variant_hasher: public boost::static_visitor<std::size_t> {
29             template <class T>
operator ()boost::detail::variant::variant_hasher30             std::size_t operator()(T const& val) const {
31                 boost::hash<T> hasher;
32                 return hasher(val);
33             }
34         };
35     }}
36 
37     template < BOOST_VARIANT_ENUM_PARAMS(typename T) >
hash_value(variant<BOOST_VARIANT_ENUM_PARAMS (T)> const & val)38     std::size_t hash_value(variant< BOOST_VARIANT_ENUM_PARAMS(T) > const& val) {
39         std::size_t seed = boost::apply_visitor(detail::variant::variant_hasher(), val);
40         hash_combine(seed, val.which());
41         return seed;
42     }
43 }
44 
45 #endif
46 
47