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

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Ranges library
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(C++23)
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template< bool Const >
struct /*inner_iterator*/;
(1) (since C++20)

The return type of lazy_split_view::outer_iterator::value_type::begin().

Const matches the template argument of outer_iterator.

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

Contents

[edit] Member types

Member type Definition
Base (private) const V if Const is true, otherwise V. The name is for exposition only.
iterator_concept equivalent to /*outer_iterator*/<Const>::iterator_concept, that is std::forward_iterator_tag if Base models forward_range, or std::forward_iterator_tag otherwise.
iterator_category
value_type ranges::range_value_t<Base>.
difference_type ranges::range_difference_t<Base>.

[edit] Data members

Typical implementations of inner_iterator hold two non-static data members:

  • An iterator of type /*outer_iterator*/<Const> (shown here as i_ for exposition only) into the underlying view of the parent lazy_split_view.
  • A boolean flag (shown here as incremented_ for exposition only) that indicates whether the operator++ was invoked on this object at least once.

[edit] Member functions

(constructor)
(C++20)
constructs an iterator
(public member function)
base
(C++20)
returns the underlying iterator
(public member function)
operator*
(C++20)
returns the current element
(public member function)
operator++operator++(int)
(C++20)
advances the iterator
(public member function)

[edit] Member functions

std::ranges::lazy_split_view::inner_iterator::inner_iterator

/*inner_iterator*/() = default;
(1) (since C++20)
constexpr explicit /*inner_iterator*/( /*outer_iterator*/<Const> i );
(2) (since C++20)
1) Value initializes the exposition-only data member i_ via its default member initializer (= /*outer_iterator*/<Const>()).
2) Initializes i_ with std::move(i).

The exposition-only data member incremented_ is initialized with its default member initializer to false.

std::ranges::lazy_split_view::inner_iterator::base

constexpr const ranges::iterator_t<Base>& base() const & noexcept;
(1) (since C++20)
constexpr ranges::iterator_t<Base> base() &&
    requires ranges::forward_range<V>;
(2) (since C++20)

Returns a copy of the underlying iterator.

1) Copy constructs the result from the underlying iterator. Equivalent to return i_./*cur*/();.
2) Move constructs the result from the underlying iterator. Equivalent to return std::move(i_./*cur*/());.

std::ranges::lazy_split_view::inner_iterator::operator*

constexpr decltype(auto) operator*() const;
(since C++20)

Returns the element the underlying iterator points to.

Equivalent to return *i_./*cur*/();.

std::ranges::lazy_split_view::inner_iterator::operator++

constexpr /*inner_iterator*/& operator++();
(1) (since C++20)
constexpr decltype(auto) operator++(int);
(2) (since C++20)
1) The function body is equivalent to
incremented_ = true;

if constexpr (!ranges::forward_range<Base>) {
  if constexpr (Pattern::size() == 0) {
    return *this;
  }
}
++i_./*cur*/();

return *this;
2) Equivalent to
if constexpr (ranges::forward_range<Base>) {

  auto tmp = *this;
  ++*this;
  return tmp;
} else {
    ++*this; // no return statement
}

[edit] Non-member functions

operator==
(C++20)
compares the iterators or the iterator and std::default_sentinel
(function)
iter_move
(C++20)
casts the result of dereferencing the underlying iterator to its associated rvalue reference type
(function)
iter_swap
(C++20)
swaps the objects pointed to by two underlying iterators
(function)

operator==(std::ranges::split_view::inner_iterator)

friend constexpr bool operator==( const /*inner_iterator*/& x,

                                  const /*inner_iterator*/& y )

      requires forward_range<Base>;
(1) (since C++20)
friend constexpr bool operator==( const /*inner_iterator*/& x,
                                  std::default_sentinel_t );
(2) (since C++20)
1) Equivalent to return x.i_./*cur*/() == y.i_./*cur*/();.
2) The function body is equivalent to
auto [pcur, pend] = ranges::subrange{x.i_.parent_->pattern_};
auto end = ranges::end(x.i_.parent_->base_);
if constexpr (/*tiny_range*/<Pattern>) {
  const auto& cur = x.i_./*cur*/();
  if (cur == end) return true;
  if (pcur == pend) return x.incremented_;
  return *cur == *pcur;
} else {
  auto cur = x.i_./*cur*/();
  if (cur == end) return true;
  if (pcur == pend) return x.incremented_;
  do {
    if (*cur != *pcur) return false;
    if (++pcur == pend) return true;
  } while (++cur != end);
  return false;
}

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::inner_iterator is an associated class of the arguments.

iter_move(std::ranges::split_view::inner_iterator)

friend constexpr decltype(auto) iter_move( const /*inner_iterator*/& i )
    noexcept(noexcept(ranges::iter_move(i.i_./*cur*/())));
(since C++20)

Equivalent to return ranges::iter_move(i.i_./*cur*/());.

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

iter_swap(std::ranges::split_view::inner_iterator)

friend constexpr void iter_swap( const /*inner_iterator*/& x,

                                 const /*inner_iterator*/& y )
  noexcept(noexcept(ranges::iter_swap(x.i_.current, y.i_.current)))

  requires std::indirectly_swappable<ranges::iterator_t<Base>>;
(since C++20)

Equivalent to ranges::iter_swap(x.i_./*cur*/(), y.i_./*cur*/()).

This function is not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when std::ranges::split_view::inner_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 3591 C++20 the && overload of base might invalidate outer iterators constraints added
LWG 3593 C++20 the const& overload of base returns a reference but might not be noexcept made noexcept