operator+,-(ranges::transform_view::iterator) - cppreference.com (original) (raw)

friend constexpr /*iterator*/ operator+( /*iterator*/ i, difference_type n ) requires ranges::random_access_range<Base>; (1) (since C++20)
friend constexpr /*iterator*/ operator+( difference_type n, /*iterator*/ i ) requires ranges::random_access_range<Base>; (2) (since C++20)
friend constexpr /*iterator*/ operator-( /*iterator*/ i, difference_type n ) requires ranges::random_access_range<Base>; (3) (since C++20)
friend constexpr difference_type operator-( const /*iterator*/& x, const /*iterator*/& y ) requires std::sized_sentinel_for<ranges::iterator_t<Base>, ranges::iterator_t<Base>>; (4) (since C++20)

1,2) Returns the iterator i incremented by n.

  1. Returns the iterator i decremented by n.

  2. Returns the distance between x and y.

These functions are not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when transform_view::_iterator_<Const> is an associated class of the arguments.

[edit] Parameters

i, x, y - the iterators.
n - position relative to current location.

[edit] Return value

Let parent_ denote the pointer to the parent transform_view, current_ denote the underlying iterator.

1,2) /*iterator*/{*i.parent_, i.current_ + n}

  1. /*iterator*/{*i.parent_, i.current_ - n}

  2. x.current_ - y.current_

[edit] Example

[edit] 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 3483 C++20 transform_view::iterator's difference is overconstrained requirement is relaxed