std::common_iterator<I,S>::common_iterator

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

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)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

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)

 

std::common_iterator

Member functions

common_iterator::common_iterator (C++20)

common_iterator::operator= (C++20)

common_iterator::operator*common_iterator::operator-> (C++20)(C++20)

common_iterator::operator++common_iterator::operator++(int) (C++20)(C++20)

Non-member functions

operator== (C++20)

operator- (C++20)

iter_move (C++20)

iter_swap (C++20)

Helper classes

incrementable_traits (C++20)

iterator_traits (C++20)

 

constexpr common_iterator() requires std::default_initializable<I> = default;	(1)	(since C++20)
constexpr common_iterator( I i );	(2)	(since C++20)
constexpr common_iterator( S s );	(3)	(since C++20)
template< class I2, class S2 > requires std::convertible_to<const I2&, I> &&          std::convertible_to<const S2&, S> constexpr common_iterator( const common_iterator<I2, S2>& x );	(4)	(since C++20)

Constructs a new iterator adaptor, effectively initializes the underlying std::variant<I, S> member object var to hold an I (iterator) or S (sentinel) object.

1) Default constructor. Default-initializes var. After construction, var holds a value-initialized I object. Operations on the resulting iterator adaptor have defined behavior if and only if the corresponding operations on a value-initialized I also have defined behavior.

2) After construction, var holds an I object move-constructed from i.

3) After construction, var holds an S object move-constructed from s.

4) After construction, var holds an I or S object initialized from the I2 or S2 held by x.var, if x.var holds that alternative, respectively. The behavior is undefined if x is in an invalid state, that is, x.var.valueless_by_exception() is equal to true.

Parameters

i	-	iterator to adapt
s	-	sentinel to adapt
x	-	iterator adaptor to copy

Example

Run this code

#include <algorithm>
#include <iostream>
#include <iterator>
#include <numeric>
#include <vector>
 
int main()
{
    std::vector v {3,1,4,1,5,9,2};
 
    using CI = std::common_iterator<
                   std::counted_iterator<std::vector<int>::iterator>,
                   std::default_sentinel_t
                   >;
    CI unused; // (1)
    CI start  { std::counted_iterator{std::next(begin(v)), ssize(v)-2} }; // (2)
    CI finish { std::default_sentinel }; // (3)
    CI first  { start };  // (4)
    CI last   { finish }; // (4)
 
    std::copy(first, last, std::ostream_iterator<int>{std::cout, " "});
    std::cout << '\n';
 
    std::common_iterator<
      std::counted_iterator<
        std::ostream_iterator<double>>,
        std::default_sentinel_t>
        beg { std::counted_iterator{std::ostream_iterator<double>{std::cout,";  "}, 5} },
        end { std::default_sentinel };
    std::iota(beg, end, 3.1);
    std::cout << '\n';
}

Output:

1 4 1 5 9
3.1;  4.1;  5.1;  6.1;  7.1;

See also

operator= (C++20)

assigns another iterator adaptor (public member function)