std::indirectly_copyable_storable

 

C++

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Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

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Numerics library

Localizations library

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Filesystem library (C++17)

Regular expressions library (C++11)

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Technical specifications

Symbols index

External libraries

 

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_const_reference_titer_rvalue_reference_titer_common_reference_t (C++20)(C++20)(C++20)(C++23)(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 (C++20)	projected (C++20)
Iterator adaptors
reverse_iterator move_iterator (C++11) move_sentinel (C++20) common_iterator (C++20) counted_iterator (C++20) basic_const_iterator (C++23) const_iterator (C++23) const_sentinel (C++23) 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) make_const_iterator (C++23) make_const_sentinel (C++23) 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>
template<class In, class Out> concept indirectly_copyable_storable =     std::indirectly_copyable<In, Out> &&     std::indirectly_writable<Out, std::iter_value_t<In>&> &&     std::indirectly_writable<Out, const std::iter_value_t<In>&> &&     std::indirectly_writable<Out, std::iter_value_t<In>&&> &&     std::indirectly_writable<Out, const std::iter_value_t<In>&&> &&     std::copyable<std::iter_value_t<In>> &&     std::constructible_from<std::iter_value_t<In>, std::iter_reference_t<In>> &&     std::assignable_from<std::iter_value_t<In>&, std::iter_reference_t<In>>;		(since C++20)

The indirectly_copyable_storable concept specifies the relationship between an indirectly_readable type and an indirectly_writable type. In addition to indirectly_copyable, this concept specifies that the copy from the indirectly_readable type can be performed via an intermediate object.

Semantic requirements

In and Out model std::indirectly_copyable_storable<In, Out> only if given a dereferenceable value i of type In:

• After the definition std::iter_value_t<In> obj(*i);, obj is equal to the value previously denoted by *i, and
• if std::iter_reference_t<In> is an rvalue reference type, *i is placed in a valid but unspecified state after the initialization of obj.

Equality preservation

An expression is equality preserving if it results in equal outputs given equal inputs.

• The inputs to an expression consist of its operands.
• The outputs of an expression consist of its result and all operands modified by the expression (if any).

In specification of standard concepts, operands are defined as the largest subexpressions that include only:

• an id-expression, and
• invocations of std::move, std::forward, and std::declval.

The cv-qualification and value category of each operand is determined by assuming that each template type parameter denotes a cv-unqualified complete non-array object type.

Every expression required to be equality preserving is further required to be stable: two evaluations of such an expression with the same input objects must have equal outputs absent any explicit intervening modification of those input objects.

Unless noted otherwise, every expression used in a requires-expression is required to be equality preserving and stable, and the evaluation of the expression may modify only its non-constant operands. Operands that are constant must not be modified.

See also

indirectly_copyable (C++20)	specifies that values may be copied from an indirectly_readable type to an indirectly_writable type (concept)
indirectly_movable_storable (C++20)	specifies that values may be moved from an indirectly_readable type to an indirectly_writable type and that the move may be performed via an intermediate object (concept)