151 lines
4.2 KiB
C++
151 lines
4.2 KiB
C++
/*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* Copyright 2015-2018 Danny Robson <danny@nerdcruft.net>
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*/
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#pragma once
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#include "index.hpp"
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#include "../types.hpp"
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#include <cstddef>
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#include <functional>
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#include <tuple>
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#include <utility>
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namespace cruft::tuple::value {
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///////////////////////////////////////////////////////////////////////////
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/// Call a provided functor of type FunctionT with each value in a
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/// provided tuple-like object TupleT
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template<
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typename FunctionT,
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typename TupleT,
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std::size_t S = 0
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>
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void
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each (FunctionT &&func, TupleT &&value)
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{
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using tuple_t = std::decay_t<TupleT>;
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static_assert (S < std::tuple_size_v<tuple_t>);
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std::invoke (func, std::get<S> (value));
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if constexpr (S + 1 < std::tuple_size_v<tuple_t>) {
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each<FunctionT,TupleT,S+1> (std::forward<FunctionT> (func), std::forward<TupleT> (value));
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}
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}
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///////////////////////////////////////////////////////////////////////////
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namespace detail {
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template <typename FuncT, typename ArgT, std::size_t ...Indices>
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auto
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map (std::index_sequence<Indices...>, FuncT &&func, ArgT &&arg)
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{
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return std::tuple (
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std::invoke (func, std::get<Indices> (arg))...
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);
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}
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};
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/// returns a tuple of the result of applying the provided function to
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/// each value of the supplied tuple.
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template <
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typename FuncT,
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typename ArgT,
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typename IndicesV = std::make_index_sequence<
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std::tuple_size_v<std::decay_t<ArgT>>
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>
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>
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auto map (FuncT &&func, ArgT &&arg)
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{
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return detail::map (
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IndicesV{},
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std::forward<FuncT> (func),
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std::forward<ArgT> (arg)
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);
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}
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///////////////////////////////////////////////////////////////////////////
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// return a tuple that contains the 'nth' element from each of the supplied
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// tuple-like arguments
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template <size_t N, typename ...TupleT>
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auto
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nth (TupleT&&...args)
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{
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return std::make_tuple (
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std::get<N> (args)...
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);
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}
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///////////////////////////////////////////////////////////////////////////
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namespace detail {
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template <typename ...TupleT, size_t ...Elements>
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auto
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zip (std::index_sequence<Elements...>, TupleT &&...args)
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{
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return std::make_tuple (
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nth<Elements> (args...)...
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);
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}
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};
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/// converts m arguments of n-tuples into one m-tuple of n-tuples by taking
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/// successive elements from each argument tuple.
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///
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/// eg, zip (('a', 1.f), (0, nullptr)) becomes (('a', 0), (1.f, nullptr))
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template <typename ...Args >
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auto
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zip (Args &&...args)
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{
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static_assert (sizeof...(args) > 0);
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// ensure all the types have the same static size
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using all_t = std::tuple<std::decay_t<Args>...>;
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using first_t = std::tuple_element_t<0,all_t>;
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static constexpr auto arity = std::tuple_size_v<first_t>;
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static_assert ((
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(arity == std::tuple_size_v<std::decay_t<Args>>) && ...
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));
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return detail::zip (
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std::make_index_sequence<arity> {},
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std::forward<Args> (args)...
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);
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}
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///////////////////////////////////////////////////////////////////////////
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namespace detail {
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template <typename TupleT, size_t ...Indices>
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auto
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reverse (index::indices<Indices...>, TupleT &&val)
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{
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return std::make_tuple (
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std::get<Indices> (val)...
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);
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}
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};
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//-------------------------------------------------------------------------
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template <typename TupleT>
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auto
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reverse (TupleT &&val)
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{
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return detail::reverse (
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index::make_reverse_t<
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std::tuple_size_v<std::decay_t<TupleT>>
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> {},
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std::forward<TupleT> (val)
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);
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}
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}
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