tuple/index: add some index sequence generators and manipulators

This commit is contained in:
Danny Robson 2018-04-05 15:18:30 +10:00
parent c570d6ad2f
commit d69a567431
3 changed files with 162 additions and 0 deletions

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@ -384,6 +384,7 @@ list (
time.hpp time.hpp
time/parse.hpp time/parse.hpp
time/parse8601.cpp time/parse8601.cpp
tuple/index.hpp
tuple/type.hpp tuple/type.hpp
tuple/value.hpp tuple/value.hpp
typeidx.cpp typeidx.cpp
@ -537,6 +538,7 @@ if (TESTS)
thread/ticketlock thread/ticketlock
time/8601 time/8601
traits traits
tuple/index
tuple/value tuple/value
tuple/type tuple/type
typeidx typeidx

34
test/tuple/index.cpp Normal file
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@ -0,0 +1,34 @@
#include "tap.hpp"
#include "tuple/index.hpp"
int
main ()
{
util::TAP::logger tap;
{
using a_t = util::tuple::index::indices<0,1,2>;
using b_t = util::tuple::index::indices<4,3>;
using result_t = util::tuple::index::cat<a_t,b_t>::type;
using expected_t = util::tuple::index::indices<0,1,2,4,3>;
tap.expect (std::is_same_v<result_t, expected_t>, "index concatenation");
}
{
using indices_t = util::tuple::index::make_indices<4>::type;
using expected_t = util::tuple::index::indices<0,1,2,3>;
tap.expect (std::is_same_v<indices_t,expected_t>, "index sequence creation");
}
{
using indices_t = util::tuple::index::make_reverse_t<4>;
using expected_t = util::tuple::index::indices<3,2,1,0>;
tap.expect (std::is_same_v<indices_t,expected_t>, "reverse index sequence creation");
}
return tap.status ();
}

126
tuple/index.hpp Normal file
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@ -0,0 +1,126 @@
/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Copyright 2018 Danny Robson <danny@nerdcruft.net>
*/
#ifndef CRUFT_UTIL_TUPLE_VALUE_HPP
#define CRUFT_UTIL_TUPLE_VALUE_HPP
#include <cstddef>
///////////////////////////////////////////////////////////////////////////
// the implementation of all the below must be standalone as they are a
// potential building block in other algorithms and we can't be sure we
// won't create a dependency loop somewhere.
namespace util::tuple::index {
///////////////////////////////////////////////////////////////////////////
template <size_t ...Indices>
struct indices {};
///////////////////////////////////////////////////////////////////////////
template <typename A, typename B>
struct cat;
//-------------------------------------------------------------------------
template <
size_t ...A,
size_t ...B
>
struct cat<
indices<A...>,
indices<B...>
> {
using type = indices<A..., B...>;
};
//-------------------------------------------------------------------------
template <typename A, typename B>
using cat_t = typename cat<A,B>::type;
///////////////////////////////////////////////////////////////////////////
namespace detail {
template <size_t N>
struct make_indices {
using type = cat_t<
typename make_indices<N-1>::type,
indices<N-1>
>;
};
template <>
struct make_indices<0> {
using type = indices<>;
};
};
//-------------------------------------------------------------------------
// create a monotonically increasing index sequence over the range [0,N)
template <size_t N>
struct make_indices {
using type = typename detail::make_indices<N>::type;
};
//-------------------------------------------------------------------------
template <size_t N>
using make_indices_t = typename make_indices<N>::type;
///////////////////////////////////////////////////////////////////////////
namespace detail {
template <typename Indices>
struct make_reverse;
template <size_t Head, size_t ...Tail>
struct make_reverse<
indices<Head,Tail...>
> {
using type = cat_t<
typename make_reverse<indices<Tail...>>::type,
indices<Head>
>;
};
template <>
struct make_reverse<
indices<>
> {
using type = indices<>;
};
};
//-------------------------------------------------------------------------
// create a montonically decreasing index sequence over the range (N-1, 0].
//
// eg, make_reverse<3> is indices<3,2,1,0>
template <size_t N>
struct make_reverse {
using type = typename detail::make_reverse<
make_indices_t<N>
>::type;
};
//-------------------------------------------------------------------------
template <size_t N>
using make_reverse_t = typename make_reverse<N>::type;
};
#endif