std::ranges::subrange::subrange(3)

NAME
std::ranges::subrange::subrange - std::ranges::subrange::subrange

Synopsis
   subrange() requires std::default_initializable<I> = default; (1) (since
                        C++20)
   constexpr subrange( /*convertible-to-non-slicing*/<I> auto i, S s ) (2) (since
     requires (!/*store-size*/); C++20)
   constexpr subrange( /*convertible-to-non-slicing*/<I> auto i, S s,
                       /*make-unsigned-like-t*/<std::iter_difference_t<I>> (3) (since
   n ) C++20)
     requires (K == ranges::subrange_kind::sized);
   template< /*different-from*/<subrange> R >
     requires ranges::borrowed_range<R> &&
              /*convertible-to-non-slicing*/<ranges::iterator_t<R>, I> && (4) (since
              std::convertible_to<ranges::sentinel_t<R>, S> C++20)
   constexpr subrange( R&& r ) requires (!/*store-size*/ ||
   ranges::sized_range<R>);
   template< ranges::borrowed_range R>
     requires /*convertible-to-non-slicing*/<ranges::iterator_t<R>, I> &&
              std::convertible_to<ranges::sentinel_t<R>, S>
     constexpr subrange( R&& r, (5) (since
   /*make-unsigned-like-t*/<std::iter_difference_t<I>> n ) C++20)
       requires (K == ranges::subrange_kind::sized)
         : subrange{ranges::begin(r), ranges::end(r), n}
     {}
   Constructs a subrange.
   If K == ranges::subrange_kind::sized && !std::sized_sentinel_for<S, I>, the size of
   the range is stored into the subrange, as if stored by a member subobject of type
   /*make-unsigned-like-t*/<std::iter_difference_t<I>>, where make-unsigned-like-t is
   an exposition-only alias template that maps each integer-like type to its
   corresponding unsigned version. Otherwise, the size is not stored. The constant
   store-size is true if the size is stored, false otherwise.
   1) Default constructor. Value-initializes the stored iterator and sentinel as if by
   default member initializers = I() and = S(), respectively. If the size is stored, it
   is initialized with 0 as if by the default member initializer = 0.
   2) Constructs a subrange from an iterator-sentinel pair. Initializes the stored
   iterator and sentinel with std::move(i) and s respectively. The behavior is
   undefined if [i, s) is not a valid range.
   3) Constructs a subrange from an iterator-sentinel pair and a size hint. Initializes
   the stored iterator and sentinel with std::move(i) and s respectively. If the size
   is stored, it is initialized with n. The behavior is undefined if [i, s) is not a
   valid range, or n is not equal to ranges::distance(i, s) explicitly converted to its
   type.
   4) Constructs a subrange from a range. Equivalent to subrange(r,
   static_cast</*make-unsigned-like-t*/<std::iter_difference_t<I>>>(ranges::size(r)))
   if the size is stored. Otherwise, equivalent to subrange(ranges::begin(r),
   ranges::end(r)).
   5) Constructs a subrange from a range and a size hint. The behavior is undefined if
   n is not equal to ranges::distance(ranges::begin(r), ranges::end(r)) explicitly
   converted to its type.
   The exposition only concept different-from is modeled by types T and U if and only
   if std::decay_t<T> and std::decay_t<U> are different types.
   The exposition only concept convertible-to-non-slicing is satisfied or modeled by
   From and To if and only if std::convertible_to<From, To> is satisfied or modeled
   respectively, and any of following conditions is satisfied:
     * either std::decay_t<From> or std::decay_t<To> is not a pointer type,
     * std::remove_pointer_t<From>(*)[] is implicitly convertible to
       std::remove_pointer_t<To>(*)[], i.e., the conversion from From to To is at most
       a qualification conversion.

Parameters
   i - iterator that denotes the beginning of the range
   s - sentinel that denotes the end of the range
   r - range
   n - size hint, must be equal to the size of the range

Notes
   The exposition-only concept convertible-to-non-slicing forbids the conversion from
   the pointer to derived class to the pointer to base class.
   Defect reports
   The following behavior-changing defect reports were applied retroactively to
   previously published C++ standards.
      DR Applied to Behavior as published Correct behavior
   LWG 3470 C++20 convertible-to-non-slicing rejected some valid made accepted
                       qualification conversions
   P2393R1 C++20 implicit conversion to an integer-class type made explicit
                       might be invalid

Example
    This section is incomplete
    Reason: no example

Category:
     * Todo no example