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Showing content from https://en.cppreference.com/w/cpp/algorithm/ranges/../../ranges/lazy_split_view/outer_iterator.html below:

std::ranges::lazy_split_view<V, Pattern>::outer_iterator - cppreference.com

template< bool Const > struct /*outer_iterator*/;

(since C++20)
(exposition only*)

The return type of lazy_split_view::begin, and of lazy_split_view::end when the underlying view is a common_range and forward_range.

If either V or Pattern is not a simple view (e.g. if ranges::iterator_t<const V> is invalid or different from ranges::iterator_t<V>), Const is true for iterators returned from the const overloads, and false otherwise. If V is a simple view, Const is true if and only if V is a forward_range.

[edit] Member types [edit] Data members Member Description Parent* parent_ (private) a pointer to the parent object lazy_split_view
(exposition-only member object*) ranges::iterator_t<Base> current_ (private)
(present only if V models forward_range) an iterator into the underlying view
(exposition-only member object*) bool trailing_empty_ (private) a flag that indicates whether an empty trailing subrange (if any) was reached
(exposition-only member object*) [edit] Member functions constructs an iterator
(public member function) returns the current subrange
(public member function)

operator++operator++(int)

advances the iterator
(public member function) returns conditionally a reference to the current_ (if present) or to the *parent_->current_
(exposition-only member function*) [edit] Member functions std::ranges::lazy_split_view::outer_iterator ::outer_iterator 1)

Value initializes the non-static data members with their default member initializer, that is:

parent_ = nullptr;,
current_ = iterator_t<Base>(); (present only if V models forward_range),

3)

Initializes

parent_

with

std::addressof(parent)

and

current_

with

std::move(current)

4) Initializes parent_ with i.parent_, current_ with std::move(i.current_), and trailing_empty_ with t.trailing_empty_.

The trailing_empty_ is initialized with its default member initializer to false.

std::ranges::lazy_split_view::outer_iterator ::operator*

constexpr value_type operator*() const;

(since C++20)

Equivalent to return value_type{*this};.

std::ranges::lazy_split_view::outer_iterator ::operator++

constexpr /*outer_iterator*/& operator++();

(1) (since C++20)

constexpr decltype(auto) operator++(int);

(2) (since C++20) 1)

The function body is equivalent to

const auto end = ranges::end(parent_->base_);
if (/*cur*/() == end)
{
    trailing_empty_ = false;
    return *this;
}
const auto [pbegin, pend] = ranges::subrange{parent_->pattern_};
if (pbegin == pend)
    ++/*cur*/();
else if constexpr (/*tiny_range*/<Pattern>)
{
    /*cur*/() = ranges::find(std::move(/*cur*/()), end, *pbegin);
    if (/*cur*/() != end)
    {
        ++/*cur*/();
        if (/*cur*/() == end)
            trailing_empty_ = true;
    }
}
else
{
    do
    {
        auto [b, p] = ranges::mismatch(/*cur*/(), end, pbegin, pend);
        if (p == pend)
        {
            /*cur*/() = b;
            if (/*cur*/() == end)
                trailing_empty_ = true;
            break; // The pattern matched; skip it
        }
    } while (++/*cur*/() != end);
}
return *this;

2)

Equivalent to

if constexpr (ranges::forward_range<Base>)
{
    auto tmp = *this;
    ++*this;
    return tmp;
}
else
{
    ++*this; // no return statement
}

std::ranges::lazy_split_view::outer_iterator ::cur ()

constexpr auto& /*cur*/() noexcept;

(1) (since C++20)
(exposition only*)

constexpr auto& /*cur*/() const noexcept;

(2) (since C++20)
(exposition only*)

This convenience member function is referred to from /*outer_iterator*/::operator++(), from the non-member operator==(const /*outer_iterator*/&, std::default_sentinel_t), and from some member functions of the possible implementation of inner_iterator.

[edit] Non-member functions compares the underlying iterators or the underlying iterator and std::default_sentinel
(function) operator==(std::ranges::split_view::outer_iterator) friend constexpr bool operator==( const /*outer_iterator*/& x, const /*outer_iterator*/& y ) requires forward_range<Base>; (1) (since C++20) (2) (since C++20)

1) Equivalent to return x.current_ == y.current_ and x.trailing_empty_ == y.trailing_empty_;.

2)

Equivalent to

return x./*cur*/() == ranges::end(x.parent_->base_) and !x.trailing_empty_;

The != operator is synthesized from operator==.

These functions are not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when std::ranges::split_view::outer_iterator is an associated class of the arguments.

[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 3904 C++20 trailing_empty_ was not initialized in constructor (4) initialized

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