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

From cppreference.net
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 .

Contents

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 is an associated class of the arguments.

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