372 lines
11 KiB
C++
372 lines
11 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 "../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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#include <functional>
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namespace cruft::tuple::type {
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///////////////////////////////////////////////////////////////////////////
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/// Invoke a provided FunctorT with the provided arguments and a
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/// type_tag<T> for each type in the tuple-like type TupleT.
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///
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/// The order of invocation is low-index to high-index (left to right).
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///
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/// \tparam TupleT A tuple-like type
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/// \tparam FunctorT An invokable type
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/// \tparam S The index to be invoked; this is private.
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/// \tparam ArgsT User supplied arguments
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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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typename ...ArgsT
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>
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void
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each (FunctorT &&func, ArgsT &&...args)
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{
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/// Get a handle on the type we need to forward.
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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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/// Call the user's invokable.
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std::invoke (func, args..., cruft::type_tag<value_type> {});
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/// Recurse into ourselves with a higher index if we haven't reached
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/// the end.
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if constexpr (S + 1 < std::tuple_size_v<TupleT>) {
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each<TupleT,FunctorT,S+1> (
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std::forward<FunctorT> (func),
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std::forward<ArgsT> (args)...
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);
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}
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}
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///////////////////////////////////////////////////////////////////////////////
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/// Convert a tuple-type holding an initial set of types into a tuple-type
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/// holding a different set of types using the supplied transform:
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/// `FieldT<...>`.
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///
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/// \tparam TupleT The initial tuple-type
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/// \tparam FieldT The type-transform type.
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/// The conversion uses FieldT<...>::type to perform the
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/// conversions.
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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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///
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/// \tparam TupleT The tuple-type to be queried
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/// \tparam ValueT The value-type we are searching for
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///
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/// The index will be defined as the size_t `::value` if it has been found.
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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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/// Remove duplicate types from the list of held types in a tuple
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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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/// Convenience accessor for the 'nth' type of a tuple.
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template <typename TupleT, std::size_t IndexV>
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struct nth;
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//-------------------------------------------------------------------------
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template <typename HeadT, typename ...TailT>
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struct nth<std::tuple<HeadT,TailT...>,0> {
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using type = HeadT;
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};
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//-------------------------------------------------------------------------
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template <typename HeadT, typename ...TailT, std::size_t IndexV>
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struct nth<std::tuple<HeadT,TailT...>,IndexV> : nth<std::tuple<TailT...>,IndexV-1> { };
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//-------------------------------------------------------------------------
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template <typename TupleT, std::size_t IndexV>
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using nth_t = typename nth<TupleT, IndexV>::type;
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///////////////////////////////////////////////////////////////////////////
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/// Extract the first CountV types of the tuple-like-object and store them
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/// in a tuple definition.
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template <
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std::size_t CountV,
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typename TupleT,
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typename Indices = std::make_index_sequence<CountV>
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>
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struct prefix;
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//-------------------------------------------------------------------------
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template <
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std::size_t CountV,
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typename TupleT,
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std::size_t ...IndexV
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>
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struct prefix<
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CountV,
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TupleT,
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std::index_sequence<IndexV...>
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> {
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using type = std::tuple<
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std::tuple_element_t<IndexV, TupleT>...
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>;
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};
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//-------------------------------------------------------------------------
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template <std::size_t CountV, typename TupleT>
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using prefix_t = typename prefix<CountV, TupleT>::type;
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};
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