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std::ranges::lazy_split_view<V, Pattern>::outer_iterator

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.

Member types

Member type Definition
Parent const ranges::lazy_split_view if Const is true, otherwise ranges::lazy_split_view
(exposition-only member type*)
Base const V if Const is true, otherwise V
(exposition-only member type*)
iterator_concept (C++20) std::forward_iterator_tag if Base models forward_range, otherwise std::input_iterator_tag
iterator_category (C++20) std::input_iterator_tag if Base models forward_range. Not present otherwise.
value_type (C++20) ranges::lazy_iterator_view<V, Pattern>
::/* outer_iterator */<Const>::value_type
difference_type (C++20) ranges::range_difference_t<Base>.

Data members

Member name Definition
parent_ (private) A pointer of type Parent* to the parent lazy_split_view object
(exposition-only member object*)
current_ (private) An iterator of type ranges::iterator_t<Base> into the underlying view; present only if V models forward_range
(exposition-only member object*)
trailing_empty_ (private) A boolean flag that indicates whether an empty trailing subrange (if any) was reached
(exposition-only member object*)

Member functions

(constructor)
(C++20)
constructs an iterator
(public member function)
operator*
(C++20)
returns the current subrange
(public member function)
operator++operator++(int)
(C++20)
advances the iterator
(public member function)
cur
(C++20)
returns conditionally a reference to the current_ (if present) or to the *parent_->current_
(exposition-only member function*)

Member functions

std::ranges::lazy_split_view::outer_iterator ::outer_iterator

/* outer_iterator */() = default;
 (1) (since C++20) 
constexpr explicit /* outer_iterator */( Parent& parent )
  requires (!ranges::forward_range<Base>);
 (2) (since C++20) 
constexpr /* outer_iterator */( Parent& parent,
                                ranges::iterator_t<Base> current )
  requires ranges::forward_range<Base>;
 (3) (since C++20) 
constexpr /* outer_iterator */( /* outer_iterator */<!Const> i )
  requires Const && std::convertible_to<ranges::iterator_t<V>,
                                        ranges::iterator_t<Base>>;
 (4) (since C++20)
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),
2) Initializes parent_ with std::addressof(parent).
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.

1,2) Equivalent to 
if constexpr (ranges::forward_range<V>)
    return current_;
else
    return *parent->current_;

Non-member functions

operator==
(C++20)
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) 
friend constexpr bool operator==( const /* outer_iterator */& x,
                                  std::default_sentinel_t );
 (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.

Nested classes

(C++20)
the value type of the outer_iterator
(public member 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 3904 C++20 trailing_empty_ was not initialized in constructor overload (4) initialized

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