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

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< cpp‎ | ranges‎ | lazy split view
C++
Ranges library
Range adaptors
std::ranges::lazy_split_view
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 Definition
Parent maybe-const <Const, ranges::lazy_split_view>
(exposition-only member type*
Base maybe-const <Const, V>
(exposition-only member type*
iterator_concept
iterator_category
(present only if Base models forward_range) 		std::input_iterator_tag
the value type of the outer_iterator
(public member class)
difference_type ranges::range_difference_t<Base>

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*

Member functions

(constructor)
 constructs an iterator
(public member function)
operator*
 returns the current subrange
(public member function)
operator++operator++(int)
 advances the iterator
(public member function)
cur
 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

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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