enumerate.hh

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#ifndef DUMUX_COMMON_ENUMERATE_HH
#define DUMUX_COMMON_ENUMERATE_HH
 
#include <tuple>
 
namespace Dumux {
 
template <typename Range,
          typename RangeIterator = decltype(std::begin(std::declval<Range>())),
          typename = decltype(std::end(std::declval<Range>()))>
constexpr auto enumerate(Range&& iterable)
{
    struct Iterator
    {
        std::size_t i;
        RangeIterator iter;
        bool operator != (const Iterator & other) const { return iter != other.iter; }
        void operator ++ () { ++i; ++iter; }
        auto operator * () const { return std::tie(i, *iter); }
    };
 
    struct Iterable
    {
        Range iterable;
        auto begin() { return Iterator{ 0, std::begin(iterable) }; }
        auto end() { return Iterator{ 0, std::end(iterable) }; }
    };
 
    return Iterable{ std::forward<Range>(iterable) };
}
 
} // end namespace Dumux
 
#endif