std::ranges::iter_move

 

C++

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Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Atomic operations library (C++11)

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Technical Specifications

 

Iterator library

Iterator concepts
indirectly_readable (C++20) indirectly_writable (C++20) weakly_incrementable (C++20) incrementable (C++20) input_or_output_iterator (C++20) sentinel_for (C++20) sized_sentinel_for (C++20)	input_iterator (C++20) output_iterator (C++20) forward_iterator (C++20) bidirectional_iterator (C++20) random_access_iterator (C++20) contiguous_iterator (C++20)
Iterator primitives
iterator_traits input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tagcontiguous_iterator_tag (C++20) iterator (deprecated in C++17)	incrementable_traits (C++20) indirectly_readable_traits (C++20) iter_value_titer_difference_titer_reference_titer_rvalue_reference_titer_common_reference_t (C++20)(C++20)(C++20)(C++20)(C++20)
Algorithm concepts and utilities
Indirect callable concepts
indirectly_unary_invocableindirectly_regular_unary_invocable (C++20)(C++20) indirect_unary_predicate (C++20)	indirect_binary_predicate (C++20) indirect_equivalence_relation (C++20) indirect_strict_weak_order (C++20)
Common algorithm requirements
indirectly_movable (C++20) indirectly_movable_storable (C++20) indirectly_copyable (C++20) indirectly_copyable_storable (C++20)	indirectly_swappable (C++20) indirectly_comparable (C++20) permutable (C++20) mergeable (C++20) sortable (C++20)
Utilities
indirect_result_t	projected
Iterator adaptors
reverse_iterator move_iterator (C++11) move_sentinel (C++20) common_iterator (C++20) counted_iterator (C++20) back_insert_iterator front_insert_iterator insert_iterator	make_reverse_iterator (C++14) make_move_iterator (C++11) default_sentinel_tdefault_sentinel (C++20)(C++20) unreachable_sentinel_tunreachable_sentinel (C++20)(C++20) back_inserter front_inserter inserter
Stream iterators
istream_iterator ostream_iterator	istreambuf_iterator ostreambuf_iterator
Iterator customization points
ranges::iter_move (C++20)
ranges::iter_swap (C++20)
Iterator operations
advance distance prev (C++11) next (C++11)	ranges::advance (C++20) ranges::distance (C++20) ranges::prev (C++20) ranges::next (C++20)
Range access
begincbegin (C++11)(C++14) endcend (C++11)(C++14) sizessize (C++17)(C++20)	rbegincrbegin (C++14)(C++14) rendcrend (C++14)(C++14) empty (C++17) data (C++17)

 

Defined in header <iterator>
inline namespace /*unspecified*/ {     inline constexpr /*unspecified*/ iter_move = /*unspecified*/; }		(since C++20) (customization point object)
Call signature
template< class T >     requires /* see below */ constexpr decltype(auto) iter_move(T&& t) noexcept(/* see below */);

Obtains an rvalue reference or a prvalue temporary from a given iterator.

A call to ranges::iter_move is expression-equivalent to:

1. iter_move(std::forward<T>(t)), if std::remove_cvref_t<T> is a class or enumeration type and the expression is well-formed in unevaluated context, where the overload resolution is performed with the following candidates:
   • void iter_move();
   • any declarations of iter_move found by argument-dependent lookup.
2. otherwise, std::move(*std::forward<T>(t)) if *std::forward<T>(t) is well-formed and is an lvalue,
3. otherwise, *std::forward<T>(t) if *std::forward<T>(t) is well-formed and is an rvalue.

In all other cases, a call to ranges::iter_move is ill-formed, which can result in substitution failure when ranges::iter_move(e) appears in the immediate context of a template instantiation.

If ranges::iter_move(e) is not equal to *e, the program is ill-formed, no diagnostic required.

Expression-equivalent

Expression e is expression-equivalent to expression f, if e and f have the same effects, either are both potentially-throwing or are both not potentially-throwing (i.e. noexcept(e) == noexcept(f)), and either are both constant subexpressions or are both not constant subexpressions.

Customization point objects

The name ranges::iter_move denotes a customization point object, which is a const function object of a literal semiregular class type (denoted, for exposition purposes, as iter_move_ftor). All instances of iter_move_ftor are equal. Thus, ranges::iter_move can be copied freely and its copies can be used interchangeably.

Given a set of types Args..., if std::declval<Args>()... meet the requirements for arguments to ranges::iter_move above, iter_move_ftor will satisfy std::invocable<const iter_move_ftor&, Args...>. Otherwise, no function call operator of iter_move_ftor participates in overload resolution.

See also

iter_move (C++20)	casts the result of dereferencing the adjusted underlying iterator to its associated rvalue reference type (function template)
iter_move (C++20)	casts the result of dereferencing the underlying iterator to its associated rvalue reference type (function template)