boost_mp11/doc/mp11/tuple.adoc

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Copyright 2017 Peter Dimov

Distributed under the Boost Software License, Version 1.0.

See accompanying file LICENSE_1_0.txt or copy at
http://www.boost.org/LICENSE_1_0.txt
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[#tuple]
# Tuple Operations, <boost/mp11/tuple.hpp>
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## tuple_apply(f, tp)

    template<class F, class Tp> constexpr /*...*/ tuple_apply(F&& f, Tp&& tp);

`tuple_apply(f, tp)` returns `std::forward<F>(f)(std::get<J>(std::forward<Tp>(tp))...)` for `J` in 0..`N-1`,
where `N` is `std::tuple_size<typename std::remove_reference<Tp>::type>::value`. Same as `std::apply` in C++17.

## construct_from_tuple<T>(tp)

    template<class T, class Tp> T construct_from_tuple(Tp&& tp);

`construct_from_tuple<T>(tp)` returns `T(std::get<J>(std::forward<Tp>(tp))...)` for `J` in 0..`N-1`,
where `N` is `std::tuple_size<typename std::remove_reference<Tp>::type>::value`. Same as `std::make_from_tuple` in {cpp}17.
The name of the function doesn't match the {cpp}17 one to avoid ambiguities when both are visible or in unqualified calls.

## tuple_for_each(tp, f)

    template<class Tp, class F> constexpr F tuple_for_each(Tp&& tp, F&& f);

`tuple_for_each(tp, f)` applies the function object `f` to each element of `tp` by evaluating the
expression `f(std::get<J>(std::forward<Tp>(tp)))` for `J` in 0..`N-1`, where `N` is `std::tuple_size<typename std::remove_reference<Tp>::type>::value`.

Returns `std::forward<F>(f)`.

## tuple_transform(f, tp...)

    template<class F, class... Tp> constexpr /*...*/ tuple_transform(F const& f, Tp&&... tp);

`tuple_transform(f, tp...)` accepts a function object `f` followed by one or more tuples of equal length
(`std::tuple`, `std::pair` and `std::array` are considered tuples.)

The callable `f` must accept as many arguments as there are tuples. The function object is called with the
first elements of each tuple, then with the second element of each tuple, and so on, as if by evaluating
the expression `f(std::get<J>(std::forward<Tp>(tp))...)` for `J` in 0..`N-1`, where `N` is the length of
the tuples.

The results are returned as a `std::tuple<T...>` with `T...` deduced from the return values of `f` (lvalue
references are preserved, rvalue references are returned by value.)

The order in which the elements of the tuples are processed is unspecified. Calling `f` should not have
side effects.