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construct/include/ircd/json/tuple/key.h

57 lines
1.2 KiB
C++

// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.
#pragma once
#define HAVE_IRCD_JSON_TUPLE_KEY_H
namespace ircd {
namespace json {
template<class tuple,
size_t i>
constexpr enable_if_tuple<tuple, const char *>
key()
noexcept
{
return tuple_element<tuple, i>::key;
}
template<size_t i,
class tuple>
inline enable_if_tuple<tuple, const char *>
key(const tuple &t)
noexcept
{
return std::get<i>(t).key;
}
template<class tuple,
size_t i>
inline typename std::enable_if<i == tuple::size(), const char *>::type
key(const size_t &j)
noexcept
{
return nullptr;
}
template<class tuple,
size_t i = 0>
inline typename std::enable_if<i < tuple::size(), const char *>::type
key(const size_t &j)
noexcept
{
if(likely(j != i))
return key<tuple, i + 1>(j);
return tuple_element<tuple, i>::key;
}
} // namespace json
} // namespace ircd