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construct/include/ircd/json/tuple/_key_transform.h
2019-01-17 14:38:18 -08:00

85 lines
1.8 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_TRANSFORM_H
namespace ircd {
namespace json {
template<class tuple,
class it_a,
class it_b,
size_t i,
class closure>
constexpr typename std::enable_if<i == tuple::size(), it_a>::type
_key_transform(it_a it,
const it_b &end,
closure&& lambda)
{
return it;
}
template<class tuple,
class it_a,
class it_b,
size_t i = 0,
class closure>
constexpr typename std::enable_if<i < tuple::size(), it_a>::type
_key_transform(it_a it,
const it_b &end,
closure&& lambda)
{
if(it != end)
{
*it = lambda(key<tuple, i>());
++it;
}
return _key_transform<tuple, it_a, it_b, i + 1>(it, end, std::forward<closure>(lambda));
}
template<class tuple,
class it_a,
class it_b>
constexpr auto
_key_transform(it_a it,
const it_b &end)
{
return _key_transform<tuple>(it, end, []
(auto&& key)
{
return key;
});
}
template<class it_a,
class it_b,
class... T>
auto
_key_transform(const tuple<T...> &tuple,
it_a it,
const it_b &end)
{
for_each(tuple, [&it, &end]
(const auto &key, const auto &val)
{
if(it != end)
{
*it = key;
++it;
}
});
return it;
}
} // namespace json
} // namespace ircd