302 lines
8.2 KiB
C++
302 lines
8.2 KiB
C++
/*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* Copyright 2015-2018 Danny Robson <danny@nerdcruft.net>
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*/
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#ifndef CRUFT_UTIL_TUPLE_TYPE_HPP
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#define CRUFT_UTIL_TUPLE_TYPE_HPP
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#include "../types.hpp"
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#include "../types/traits.hpp"
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#include <cstddef>
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#include <tuple>
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namespace util::tuple::type {
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///////////////////////////////////////////////////////////////////////////
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/// call a provided FunctorT with type_tag<T> for each type in the
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/// tuple-like type TupleT.
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template<
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typename TupleT,
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typename FunctorT,
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size_t S = 0
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>
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void
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each (FunctorT &&func)
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{
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static_assert (S < std::tuple_size_v<TupleT>);
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using value_type = typename std::tuple_element<S,TupleT>::type;
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func (util::type_tag<value_type> {});
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if constexpr (S + 1 < std::tuple_size_v<TupleT>) {
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each<TupleT,FunctorT,S+1> (std::forward<FunctorT> (func));
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}
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}
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///////////////////////////////////////////////////////////////////////////////
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/// Statically map the member types of a tuple via F<>::type
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///
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/// TupleT: tuple type
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/// FieldT: type mapping object, conversion uses FieldT<>::type
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/// Indices: tuple indexing helper
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template <
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typename TupleT,
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template <
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typename
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> class FieldT,
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typename Indices = std::make_index_sequence<
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std::tuple_size<TupleT>::value
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>
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>
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struct map;
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//-----------------------------------------------------------------------------
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template <
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typename TupleT,
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template <
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typename
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> class FieldT,
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size_t ...Indices
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>
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struct map<
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TupleT,
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FieldT,
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std::index_sequence<Indices...>
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> {
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typedef std::tuple<
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typename FieldT<
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typename std::tuple_element<Indices, TupleT>::type
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>::type...
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> type;
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};
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///////////////////////////////////////////////////////////////////////////
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/// query the index of the first occurrence of type `T' in the tuple-like
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/// type `TupleT'.
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///
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/// if the query type does not occur in the tuple type a compiler error
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/// should be generated.
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template<
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typename TupleT,
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typename ValueT,
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typename = std::make_index_sequence<
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std::tuple_size_v<TupleT>
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>
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>
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struct index { };
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//-------------------------------------------------------------------------
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// specialisation for tuples with matching first elements. the index is 0.
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template<
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typename ValueT,
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typename ...TailT,
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size_t ...Indices
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>
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struct index<
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std::tuple<ValueT, TailT...>,
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ValueT,
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std::index_sequence<Indices...>
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> {
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static constexpr std::size_t value = 0;
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};
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//-------------------------------------------------------------------------
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// specialisation for tuples with non-matching first elements.
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// increment and recurse.
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template<
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typename ValueT,
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typename HeadT,
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typename ...TailT,
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size_t ...Indices
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>
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struct index<
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std::tuple<HeadT, TailT...>,
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ValueT,
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std::index_sequence<Indices...>
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> {
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static constexpr std::size_t value = 1u + index<std::tuple<TailT...>,ValueT>::value;
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};
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//-------------------------------------------------------------------------
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// convert the tuple type (which is not a tuple or it would have matched
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// the tuple specialisation, into the equivalent std::tuple and requery
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// against that.
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template <
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typename TupleT,
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typename ValueT,
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size_t ...Indices
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> struct index<
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TupleT,
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ValueT,
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std::index_sequence<Indices...>
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> {
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static constexpr std::size_t value = index<
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std::tuple<std::tuple_element_t<Indices,TupleT>...>,
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ValueT,
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std::index_sequence<Indices...>
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>::value;
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};
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///////////////////////////////////////////////////////////////////////////
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// transform a tuple-like type (ie, something that responds to
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// tuple_element) into a tuple
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template <
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typename TupleT,
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typename Indices = std::make_index_sequence<
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std::tuple_size_v<TupleT>
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>
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> struct entuple;
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//-------------------------------------------------------------------------
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template <
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typename TupleT,
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size_t ...Indices
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> struct entuple<
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TupleT,
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std::index_sequence<Indices...>
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> {
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using type = std::tuple<
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std::tuple_element_t<Indices,TupleT>...
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>;
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};
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//-------------------------------------------------------------------------
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template <typename T>
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using entuple_t = typename entuple<T>::type;
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///////////////////////////////////////////////////////////////////////////
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// concatenate a variadic collection of tuple-like types
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template <typename ...Args>
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struct cat;
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//-------------------------------------------------------------------------
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template <>
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struct cat<> { using type = std::tuple<>; };
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//-------------------------------------------------------------------------
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template <typename HeadT, typename ...TailT>
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struct cat<HeadT,TailT...> {
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using type = decltype(
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std::tuple_cat (
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std::declval<
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entuple_t<HeadT>
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> (),
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std::declval<
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typename cat<TailT...>::type
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> ()
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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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using cat_t = typename cat<TupleT...>::type;
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///////////////////////////////////////////////////////////////////////////
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// remove a type from a tuple-like type
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template <
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typename DoomedT,
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typename TupleT
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>
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struct remove;
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//-------------------------------------------------------------------------
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template <
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typename DoomedT
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> struct remove<
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DoomedT,
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std::tuple<>
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> {
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using type = std::tuple<>;
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};
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//-------------------------------------------------------------------------
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template <
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typename DoomedT,
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typename HeadT,
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typename ...TailT
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>
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struct remove<
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DoomedT,
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std::tuple<HeadT,TailT...>
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> {
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using type = cat_t<
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std::conditional_t<
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std::is_same_v<DoomedT,HeadT>,
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std::tuple< >,
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std::tuple<HeadT>
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>,
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typename remove<DoomedT,std::tuple<TailT...>>::type
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>;
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};
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//-------------------------------------------------------------------------
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template <typename DoomedT, typename TupleT>
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using remove_t = typename remove<DoomedT,TupleT>::type;
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///////////////////////////////////////////////////////////////////////////
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template <typename TupleT>
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struct unique;
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//-------------------------------------------------------------------------
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template <>
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struct unique<std::tuple<>> { using type = std::tuple<>; };
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//-------------------------------------------------------------------------
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template <typename HeadT, typename ...TailT>
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struct unique<
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std::tuple<HeadT, TailT...>
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> {
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using type = cat_t<
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std::tuple<HeadT>,
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typename unique<
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typename remove<
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HeadT,
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std::tuple<TailT...>
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>::type
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>::type
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>;
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};
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//-------------------------------------------------------------------------
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template <typename T>
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using unique_t = typename unique<T>::type;
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}
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#endif
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