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

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Ranges library
Range primitives
Range concepts
Views

Range factories
Range adaptors
 
 
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.

Contents

[edit] 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>

[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

(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*)

[edit] 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_;

[edit] 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.

[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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