std::experimental::ranges::dangling, std::experimental::ranges::safe_iterator_t

 

C++

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Technical Specifications

 

Technical specifications

Filesystem library (filesystem TS)

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Extensions for parallelism 2 (parallelism TS v2)

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Ranges

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Iterators library

Iterator concepts
Readable Writable WeaklyIncrementable Incrementable	Iterator Sentinel SizedSentinel	InputIterator ForwardIterator BidirectionalIterator RandomAccessIterator	OutputIterator
Indirect callable concepts
IndirectUnaryInvocableIndirectRegularUnaryInvocable	IndirectUnaryPredicate	IndirectRelation	IndirectStrictWeakOrder
Common algorithm requirements
IndirectlyMovable IndirectlyMovableStorable	IndirectlyCopyable IndirectlyCopyableStorable	IndirectlySwappable IndirectlyComparable	Permutable Mergeable Sortable
Concept utilities
indirect_result_of	projected
Iterator utilities and operations
iter_move iter_swap	advance distance	next prev
Iterator traits
difference_type value_type reference_trvalue_reference_titer_common_reference_t iterator_category	input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tag	ranges::iterator_traits std::iterator_traits<InputIterator>std::iterator_traits<OutputIterator>
Iterator adaptors
reverse_iterator move_iterator move_sentinel	back_insert_iterator front_insert_iterator insert_iterator	common_iterator counted_iterator default_sentinel	danglingsafe_iterator_t unreachable
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istream_iterator	ostream_iterator	istreambuf_iterator	ostreambuf_iterator

 

Defined in header <experimental/ranges/iterator>
template <CopyConstructible T> class dangling { public:     dangling() requires DefaultConstructible<T>();     dangling(T t);     T get_unsafe() const; };		(ranges TS)
template<Range R> using safe_iterator_t = std::conditional_t<std::is_lvalue_reference<R>::value,                                            ranges::iterator_t<R>,                                            ranges::dangling<ranges::iterator_t<R>>;		(ranges TS)

The class template dangling is a simple wrapper around an object to indicate that the wrapped object may be dangling, that is, it refers to another object whose lifetime may have ended.

The alias template safe_iterator_t returns the iterator type of R, wrapped in dangling if the range was an rvalue range (as indicated by R not being an lvalue reference type).

They are used by range algorithms that accept rvalue ranges and return iterators into them.

Member functions

std::experimental::ranges::dangling::dangling

dangling() requires DefaultConstructible<T>();	(1)
dangling(T t);	(2)

1) Default constructor. Value-initializes the wrapped object.

2) Initializes the wrapped object with t. Note that this constructor defines an implicit conversion from T to dangling<T>.

std::experimental::ranges::dangling::get_unsafe

T get_unsafe() const;

Returns a copy of the wrapped object.