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construct/include/ircd/util/tuple.h

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// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
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// 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
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// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.
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#pragma once
#define HAVE_IRCD_UTIL_TUPLE_H
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//
// Utilities for std::tuple
//
namespace ircd {
inline namespace util {
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template<class tuple>
constexpr bool
is_tuple()
{
return is_specialization_of<tuple, std::tuple>::value;
}
template<class tuple>
constexpr typename std::enable_if<is_tuple<tuple>(), size_t>::type
size()
{
return std::tuple_size<tuple>::value;
}
template<class... args>
constexpr size_t
size(const std::tuple<args...> &t)
{
return size<std::tuple<args...>>();
}
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//
// Iteration of a tuple
//
// for_each(tuple, [](auto&& elem) { ... });
template<size_t i = 0,
class func,
class... args>
constexpr inline bool
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for_each(const std::tuple<args...> &t,
func&& f)
{
if constexpr(i < size<std::tuple<args...>>())
{
using closure_result = std::invoke_result_t
<
decltype(f), decltype(std::get<i>(t))
>;
constexpr bool terminable
{
std::is_same<closure_result, bool>()
};
if constexpr(terminable)
{
if(!f(std::get<i>(t)))
return false;
}
else f(std::get<i>(t));
return for_each<i + 1, func, args...>(t, std::forward<func>(f));
}
else return true;
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}
template<size_t i = 0,
class func,
class... args>
constexpr inline bool
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for_each(std::tuple<args...> &t,
func&& f)
{
if constexpr(i < size<std::tuple<args...>>())
{
using closure_result = std::invoke_result_t
<
decltype(f), decltype(std::get<i>(t))
>;
constexpr bool terminable
{
std::is_same<closure_result, bool>()
};
if constexpr(terminable)
{
if(!f(std::get<i>(t)))
return false;
}
else f(std::get<i>(t));
return for_each<i + 1, func, args...>(t, std::forward<func>(f));
}
else return true;
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}
//
// Circuits for reverse iteration of a tuple
//
// rfor_each(tuple, [](auto&& elem) { ... });
template<class func,
class... args,
ssize_t i = size<std::tuple<args...>>() - 1>
constexpr inline bool
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rfor_each(const std::tuple<args...> &t,
func&& f)
{
if constexpr(i >= 0)
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{
using closure_result = std::invoke_result_t
<
decltype(f), decltype(std::get<i>(t))
>;
constexpr bool terminable
{
std::is_same<closure_result, bool>()
};
if constexpr(terminable)
{
if(!f(std::get<i>(t)))
return false;
}
else f(std::get<i>(t));
return rfor_each<func, args..., i - 1>(t, std::forward<func>(f));
}
else return true;
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}
template<class func,
class... args,
ssize_t i = size<std::tuple<args...>>() - 1>
constexpr inline bool
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rfor_each(std::tuple<args...> &t,
func&& f)
{
if constexpr(i >= 0)
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{
using closure_result = std::invoke_result_t
<
decltype(f), decltype(std::get<i>(t))
>;
constexpr bool terminable
{
std::is_same<closure_result, bool>()
};
if constexpr(terminable)
{
if(!f(std::get<i>(t)))
return false;
}
else f(std::get<i>(t));
return rfor_each<func, args..., i - 1>(t, std::forward<func>(f));
}
else return true;
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}
//
// test() is a logical inversion of for_each() for intuitive find()-like
// boolean semantics.
//
template<class func,
class... args>
constexpr inline auto
test(const std::tuple<args...> &t,
func&& f)
{
return !for_each(t, [&f](const auto &arg)
{
return !f(arg);
});
}
template<class func,
class... args>
constexpr inline auto
rtest(const std::tuple<args...> &t,
func&& f)
{
return !rfor_each(t, [&f](const auto &arg)
{
return !f(arg);
});
}
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//
// Kronecker delta
//
template<size_t j,
size_t i,
class func,
class... args>
constexpr typename std::enable_if<i == j, void>::type
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kronecker_delta(const std::tuple<args...> &t,
func&& f)
{
using value_type = typename std::tuple_element<i, std::tuple<args...>>::type;
f(static_cast<const value_type &>(std::get<i>(t)));
}
template<size_t i,
size_t j,
class func,
class... args>
constexpr typename std::enable_if<i == j, void>::type
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kronecker_delta(std::tuple<args...> &t,
func&& f)
{
using value_type = typename std::tuple_element<i, std::tuple<args...>>::type;
f(static_cast<value_type &>(std::get<i>(t)));
}
template<size_t j,
size_t i = 0,
class func,
class... args>
constexpr typename std::enable_if<(i < j), void>::type
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kronecker_delta(const std::tuple<args...> &t,
func&& f)
{
kronecker_delta<j, i + 1>(t, std::forward<func>(f));
}
template<size_t j,
size_t i = 0,
class func,
class... args>
constexpr typename std::enable_if<(i < j), void>::type
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kronecker_delta(std::tuple<args...> &t,
func&& f)
{
kronecker_delta<j, i + 1>(t, std::forward<func>(f));
}
/// Get the index of a tuple element by address at runtime
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template<class tuple>
inline size_t
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indexof(tuple &t, const void *const &ptr)
{
size_t ret(0);
const auto closure([&ret, &ptr]
(auto &elem)
{
if(reinterpret_cast<const void *>(std::addressof(elem)) == ptr)
return false;
++ret;
return true;
});
if(unlikely(until(t, closure)))
throw std::out_of_range("no member of this tuple with that address");
return ret;
}
//// Tuple layouts are not standard layouts; we can only do this at runtime
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template<size_t index,
class tuple>
inline off_t
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tuple_offset(const tuple &t)
{
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return off_t
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{
reinterpret_cast<const uint8_t *>(std::addressof(std::get<index>(t))) -
reinterpret_cast<const uint8_t *>(std::addressof(t))
};
}
} // namespace util
} // namespace ircd