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| author | Adrian Kummerlaender | 2015-02-08 20:38:00 +0100 |
|---|---|---|
| committer | Adrian Kummerlaender | 2015-02-08 20:38:00 +0100 |
| commit | beb46377c075ccc07a22b45771f8ad993a4e088e (patch) | |
| tree | feffecf2f07b8f672cd1fcee80a63291824b7b04 | |
| parent | dd504e4fcbf73750097024dce397754dc5883386 (diff) | |
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Implemented higher order `Sort` list operation
* _Quicksort_ is the algorithm of choice
** it lends itself quite well to the _TypeAsValue_ approach because of its recursive nature
** this required implementation of a `Drop` counterpart to `Take`
* the middle item of a given list is selected as the _pivot_ element
* the `List` list contructor had to be expanded to allow `void` arguments inside its variadic parameter pack
* added appropriate test cases
| -rw-r--r-- | src/list/list.h | 11 | ||||
| -rw-r--r-- | src/list/operation/higher/sort.h | 46 | ||||
| -rw-r--r-- | test.cc | 72 |
3 files changed, 127 insertions, 2 deletions
diff --git a/src/list/list.h b/src/list/list.h index 2e335e2..d2a5cb0 100644 --- a/src/list/list.h +++ b/src/list/list.h @@ -21,6 +21,16 @@ struct List<Head> { typedef typename Cons<Head, void>::type type; }; +template <typename Head> +struct List<Head, void> { + typedef typename List<Head>::type type; +}; + +template <typename... Tail> +struct List<void, Tail...> { + typedef typename List<Tail...>::type type; +}; + template < typename Type, Type... Values @@ -40,6 +50,7 @@ using Tail = typename Cdr<Cons>::type; #include "operation/basic.h" #include "operation/nth.h" #include "operation/take.h" +#include "operation/drop.h" #include "operation/append.h" #include "operation/concatenate.h" diff --git a/src/list/operation/higher/sort.h b/src/list/operation/higher/sort.h new file mode 100644 index 0000000..0ff5c40 --- /dev/null +++ b/src/list/operation/higher/sort.h @@ -0,0 +1,46 @@ +#ifndef TYPEASVALUE_SRC_LIST_OPERATION_HIGHER_SORT_H_ +#define TYPEASVALUE_SRC_LIST_OPERATION_HIGHER_SORT_H_ + +#include "filter.h" +#include "list/operation/concatenate.h" + +namespace tav { + +template < + template<typename, typename> class Comparator, + typename Sequence +> +class Sort { + private: + using index = Divide<typename Length<Sequence>::type, Size<2>>; + using pivot = typename Nth<index, Sequence>::type; + + using sequence_sans_pivot = typename Append< + typename Take<index, Sequence>::type, + typename Drop<Add<index, Size<1>>, Sequence>::type + >::type; + + template <typename X> + using comparator_wrapper = Comparator<pivot, X>; + + using lhs = typename Filter<comparator_wrapper, sequence_sans_pivot>::type; + using rhs = typename Remove<comparator_wrapper, sequence_sans_pivot>::type; + + public: + typedef typename Concatenate< + typename List< + typename Sort<Comparator, lhs>::type, + typename List<pivot>::type, + typename Sort<Comparator, rhs>::type + >::type + >::type type; +}; + +template <template<typename, typename> class Comparator> +struct Sort<Comparator, void> { + typedef void type; +}; + +} + +#endif // TYPEASVALUE_SRC_LIST_OPERATION_HIGHER_SORT_H_ @@ -14,6 +14,7 @@ #include "list/operation/higher/find.h" #include "list/operation/higher/take_while.h" #include "list/operation/higher/drop_while.h" +#include "list/operation/higher/sort.h" #include "list/generator/iota.h" #include "list/generator/make_list.h" #include "list/generator/higher/list_tabulate.h" @@ -282,7 +283,7 @@ static_assert( tav::Pair<tav::Int<1>, void>, tav::List<tav::Int<1>>::type >::value, - "(list 1) != (cons 1 void)" + "(list 1) != '(1)" ); static_assert( @@ -290,7 +291,15 @@ static_assert( tav::Pair<tav::Int<1>, tav::Pair<tav::Int<2>, void>>, tav::List<tav::Int<1>, tav::Int<2>>::type >::value, - "(list 1 2) != (cons 1 (cons 2 void))" + "(list 1 2) != '(1 . 2)" +); + +static_assert( + std::is_same< + tav::Pair<tav::Int<1>, tav::Pair<tav::Int<2>, void>>, + tav::List<void, tav::Int<1>, void, tav::Int<2>, void>::type + >::value, + "(list void 1 void 2 void) != '(1 . 2)" ); // list of type @@ -403,6 +412,41 @@ static_assert( "(take 3 (list 1 2)) != (list 1 2)" ); +// list drop + +static_assert( + std::is_same< + tav::List<tav::Int<2>>::type, + tav::Drop< + tav::Size<1>, + tav::List<tav::Int<1>, tav::Int<2>>::type + >::type + >::value, + "(drop 1 (list 1 2)) != (list 2)" +); + +static_assert( + std::is_same< + void, + tav::Drop< + tav::Size<2>, + tav::List<tav::Int<1>, tav::Int<2>>::type + >::type + >::value, + "(drop 2 (list 1 2)) != void" +); + +static_assert( + std::is_same< + void, + tav::Drop< + tav::Size<3>, + tav::List<tav::Int<1>, tav::Int<2>>::type + >::type + >::value, + "(drop 3 (list 1 2)) != void" +); + // list append static_assert( @@ -853,6 +897,30 @@ static_assert( "(drop-while even? (list 2 4 6)) != void" ); +// list sort + +static_assert( + std::is_same< + tav::List<tav::Int<1>, tav::Int<2>, tav::Int<3>>::type, + tav::Sort< + tav::GreaterThan, + tav::List<tav::Int<3>, tav::Int<2>, tav::Int<1>>::type + >::type + >::value, + "(sort > (list 3 2 1)) != (list 1 2 3)" +); + +static_assert( + std::is_same< + tav::List<tav::Int<3>, tav::Int<2>, tav::Int<1>>::type, + tav::Sort< + tav::LowerThan, + tav::List<tav::Int<1>, tav::Int<3>, tav::Int<2>>::type + >::type + >::value, + "(sort < (list 1 3 2)) != (list 3 2 1)" +); + // function apply static_assert( |