Unpack Tuple

[maierlars]

This adds a new function unpackTuple<T_1, T_2, ..., T_n> to Slice and ArrayIterator. It can be used to unpack values from an array given their types. Given a type a Extractor<T> is used to extract the type from a slice. Thus we can easily add more types and even user code can provide specializations for their types to extract them.

unpackTuple extracts the first n elements from a Slice and reads n elements from an ArrayIterator.

auto t = s.unpackTuple<std::string, int, bool, Slice>();
static_assert(std::is_same_v<decltype(t), std::tuple<std::string, int, bool, Slice>>);

Supported types are:

• std::string
• arithmetic types (std::is_artihmetic)
• bool
• StringRef
• Slice
• std::string_view (c++17 only)

As by-product it also adds extract<T> to slice.

[coveralls]

Coverage decreased (-0.02%) to 96.409% when pulling 6ad6cf2c77ce6fcd41f65a93d0168fcd0007a499 on feature/unpack-tuple into 390fc4c8dfec7c70704b22b0eafafc5d1f08b44a on main.