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

164 lines
3.1 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_AT_H
namespace ircd {
namespace json {
template<size_t hash,
class tuple>
inline enable_if_tuple<tuple, const tuple_value_type<tuple, indexof<tuple, hash>()> &>
at(const tuple &t)
{
constexpr size_t idx
{
indexof<tuple, hash>()
};
const auto &ret
{
val<idx>(t)
};
if(unlikely(!defined(json::value(ret))))
throw not_found
{
"%s", key<idx>(t)
};
return ret;
}
template<size_t hash,
class tuple>
inline enable_if_tuple<tuple, tuple_value_type<tuple, indexof<tuple, hash>()> &>
at(tuple &t)
{
constexpr size_t idx
{
indexof<tuple, hash>()
};
auto &ret
{
val<idx>(t)
};
if(unlikely(!defined(json::value(ret))))
throw not_found
{
"%s", key<idx>(t)
};
return ret;
}
template<const char *const &name,
class tuple>
inline enable_if_tuple<tuple, const tuple_value_type<tuple, indexof<tuple, name>()> &>
at(const tuple &t)
{
return at<name_hash(name), tuple>(t);
}
template<const char *const &name,
class tuple>
inline enable_if_tuple<tuple, tuple_value_type<tuple, indexof<tuple, name>()> &>
at(tuple &t)
{
return at<name_hash(name), tuple>(t);
}
template<class tuple,
class function,
size_t i = 0>
inline enable_if_tuple<tuple, void>
at(tuple &t,
const string_view &name,
function&& f)
{
if constexpr(i < size<tuple>())
{
if(_constexpr_equal(name, key<tuple, i>()))
f(val<i>(t));
else
at<tuple, function, i + 1>(t, name, std::forward<function>(f));
}
else throw not_found
{
"%s", name
};
}
template<class tuple,
class function,
size_t i = 0>
inline enable_if_tuple<tuple, void>
at(const tuple &t,
const string_view &name,
function&& f)
{
if constexpr(i < size<tuple>())
{
if(_constexpr_equal(name, key<tuple, i>()))
f(val<i>(t));
else
at<tuple, function, i + 1>(t, name, std::forward<function>(f));
}
else throw not_found
{
"%s", name
};
}
template<class R,
class tuple>
inline enable_if_tuple<tuple, const R &>
at(const tuple &t,
const string_view &name)
{
const R *ret;
at(t, name, [&ret](auto&& val) noexcept
{
//XXX is_pointer_interconvertible_base_of? (C++20)
if constexpr(std::is_assignable<R, decltype(val)>())
ret = std::addressof(val);
else
assert(false);
});
return *ret;
}
template<class R,
class tuple>
inline enable_if_tuple<tuple, R &>
at(tuple &t,
const string_view &name)
{
R *ret;
at(t, name, [&ret]
(auto &val)
noexcept
{
//XXX is_pointer_interconvertible_base_of? (C++20)
if constexpr(std::is_assignable<R, decltype(val)>())
ret = std::addressof(val);
else
assert(false);
});
return *ret;
}
} // namespace json
} // namespace ircd