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| author | Adrian Kummerlaender | 2015-02-16 16:29:50 +0100 |
|---|---|---|
| committer | Adrian Kummerlaender | 2015-02-16 16:29:50 +0100 |
| commit | 45c63c95293e42860ee17368ab24cc65cc60d378 (patch) | |
| tree | d8fb63e2f75726ed369322faf9323fe1325a7765 | |
| parent | 324988569183e38e9c5e42318571693a6fcd9569 (diff) | |
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Reimplemented `Nth` in terms of `Drop`
| -rw-r--r-- | src/list/operation/nth.h | 37 |
1 files changed, 6 insertions, 31 deletions
diff --git a/src/list/operation/nth.h b/src/list/operation/nth.h index 5a604f4..0a56ba3 100644 --- a/src/list/operation/nth.h +++ b/src/list/operation/nth.h @@ -2,44 +2,19 @@ #define TYPEASVALUE_SRC_LIST_OPERATION_NTH_H_ #include "operation/math.h" +#include "drop.h" namespace tav { -namespace detail { - -template < - typename Index, - typename List -> -struct Nth { - typedef Eval<Nth< - Substract<Index, Size<1>>, - Tail<List> - >> type; -}; - -template <typename List> -struct Nth<Size<0>, List> { - typedef Head<List> type; -}; - -template <typename Index> -struct Nth<Index, void> { - typedef void type; -}; - -template <> -struct Nth<Size<0>, void> { - typedef void type; -}; - -} - template < typename Index, typename List > -using Nth = Eval<detail::Nth<Index, List>>; +using Nth = If< + IsPair<Drop<Index, List>>, + Head<Drop<Index, List>>, + void +>; template <typename List> using First = Nth<Size<0>, List>; |