nerdcruft/libcruft-util
1
0
Fork 0
Code Issues Releases Activity

tuple: add `index' type query for tuple types

Browse Source 
util::tuple::index finds the first occurence of a type in a tuple and
gives the index of this type.
This commit is contained in:
Danny Robson 2017-07-11 11:07:48 +10:00
parent af3dcbb418
commit b9ca3f6969
1 changed files with 25 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
tuple.hpp
View File

@ -185,7 +185,31 @@ namespace util::tuple {
{
ignore (std::forward<Args> (args)...);
};
}
///////////////////////////////////////////////////////////////////////////
/// query the index of the first occurrence of type `T' in the tuple type
/// `TupleT'.
///
/// if the query type does not occur in the tuple type a compiler error
/// should be generated.
template <class T, class TupleT>
struct index;
//-------------------------------------------------------------------------
template <class T, class ...Types>
struct index<T, std::tuple<T, Types...>> {
static constexpr std::size_t value = 0;
};
//-------------------------------------------------------------------------
template <class T, class U, class ...Types>
struct index<T,std::tuple<U, Types...>> {
static constexpr std::size_t value = 1 + index<T, std::tuple<Types...>>::value;
};
};
#endif