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https://github.com/SerenityOS/serenity
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3bf77f01a7
Also add IndexSequence and associated helpers. The TypeList class can be queried for what type is at a certain index, and there are two helper functions: for_each_type, and for_each_type_zipped. for_each_type will invoke a lambda with a TypeWrapper object for each type in the type list. The original type can be obtained by extracting the ::Type from the type of your generic lambda's one argument. for_each_type_zipped will walk two TypeLists in lockstep and pass a TypeWrapper object for the current index in each list to a generic lambda. The original type from the TypeList can again be extracted via the ::Type of the generic lambda's two parameters.
94 lines
3.1 KiB
C++
94 lines
3.1 KiB
C++
/*
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* Copyright (c) 2020, the SerenityOS developers.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include <AK/StdLibExtras.h>
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namespace AK {
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template<typename... Types>
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struct TypeList;
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template<unsigned Index, typename List>
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struct TypeListElement;
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template<unsigned Index, typename Head, typename... Tail>
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struct TypeListElement<Index, TypeList<Head, Tail...>>
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: TypeListElement<Index - 1, TypeList<Tail...>> {
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};
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template<typename Head, typename... Tail>
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struct TypeListElement<0, TypeList<Head, Tail...>> {
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using Type = Head;
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};
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template<typename... Types>
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struct TypeList {
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static constexpr unsigned size = sizeof...(Types);
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template<unsigned N>
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using Type = typename TypeListElement<N, TypeList<Types...>>::Type;
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};
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template<typename T>
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struct TypeWrapper {
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using Type = T;
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};
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template<typename List, typename F, unsigned... Indexes>
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constexpr void for_each_type_impl(F&& f, IndexSequence<Indexes...>)
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{
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(forward<F>(f)(TypeWrapper<typename List::Type<Indexes>> {}), ...);
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}
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template<typename List, typename F>
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constexpr void for_each_type(F&& f)
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{
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for_each_type_impl<List>(forward<F>(f), MakeIndexSequence<List::size> {});
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}
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template<typename ListA, typename ListB, typename F, unsigned... Indexes>
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constexpr void for_each_type_zipped_impl(F&& f, IndexSequence<Indexes...>)
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{
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(forward<F>(f)(TypeWrapper<typename ListA::Type<Indexes>> {}, TypeWrapper<typename ListB::Type<Indexes>> {}), ...);
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}
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template<typename ListA, typename ListB, typename F>
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constexpr void for_each_type_zipped(F&& f)
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{
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static_assert(ListA::size == ListB::size, "Can't zip TypeLists that aren't the same size!");
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for_each_type_zipped_impl<ListA, ListB>(forward<F>(f), MakeIndexSequence<ListA::size> {});
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}
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}
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using AK::for_each_type;
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using AK::for_each_type_zipped;
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using AK::TypeList;
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using AK::TypeListElement;
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using AK::TypeWrapper;
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