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

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

(1)

(since C++20)

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.

The name of this class template (shown here as /*outer_iterator*/) is unspecified.

Member types

Member type	Definition
`Parent` (private)	`const ranges::lazy_split_view` if `Const` is `true`, otherwise `ranges::lazy_split_view`. The name is for exposition only.
`Base` (private)	`const V` if `Const` is `true`, otherwise `V`. The name is for exposition only.
`iterator_concept`	`std::forward_iterator_tag` if `Base` models `forward_range`, otherwise `std::forward_iterator_tag`.
`iterator_category`	`std::input_iterator_tag` if `Base` models `forward_range`. Not present otherwise.
`value_type`	`ranges::lazy_iterator_view<V, Pattern>::/outer_iterator/<Const>::value_type`.
`difference_type`	`ranges::range_difference_t<Base>`.

Data members

Typical implementations of outer_iterator hold two or three non-static data members:

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

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 exposition-only 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_ and current_ with std::move(i.current_).

The exposition-only non-static data member 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; // exposition only	(1)	(since C++20)
constexpr auto& /cur/() const noexcept; // exposition only	(2)	(since C++20)

This exposition-only 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

value_type

(C++20)

the value type of the outer_iterator
(public member class)

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Last Updated	2022-06-02T22:02:33Z