deduction guides for std::forward_list

 

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forward_list (C++11)

list

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std::forward_list

Member functions

forward_list::forward_list

forward_list::~forward_list

forward_list::operator=

forward_list::assign

forward_list::assign_range (C++23)

forward_list::get_allocator

Element access

forward_list::front

Iterators

forward_list::before_beginforward_list::cbefore_begin

forward_list::beginforward_list::cbegin

forward_list::endforward_list::cend

Capacity

forward_list::empty

forward_list::max_size

Modifiers

forward_list::clear

forward_list::insert_after

forward_list::emplace_after

forward_list::insert_range_after (C++23)

forward_list::erase_after

forward_list::push_front

forward_list::emplace_front

forward_list::prepend_range (C++23)

forward_list::pop_front

forward_list::resize

forward_list::swap

Operations

forward_list::merge

forward_list::splice_after

forward_list::removeforward_list::remove_if

forward_list::reverse

forward_list::unique

forward_list::sort

Non-member functions

std::swap

eraseerase_if (C++20)(C++20)

operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)

Deduction guides(C++17)

 

Defined in header <forward_list>
template< class InputIt,           class Alloc = std::allocator<               typename std::iterator_traits<InputIt>::value_type> > forward_list( InputIt, InputIt, Alloc = Alloc() )   -> forward_list<typename std::iterator_traits<InputIt>::value_type, Alloc>;	(1)	(since C++17)
template< ranges::input_range R,           class Alloc = std::allocator<ranges::range_value_t<R>> > forward_list( std::from_range_t, R&&, Alloc = Alloc() )   -> forward_list<ranges::range_value_t<R>, Alloc>;	(2)	(since C++23)

1) This deduction guide is provided for forward_list to allow deduction from an iterator range. This overload participates in overload resolution only if InputIt satisfies LegacyInputIterator and Alloc satisfies Allocator.

2) This deduction guide is provided for forward_list to allow deduction from a std::from_range_t tag and an input_range.

Note: the extent to which the library determines that a type does not satisfy LegacyInputIterator is unspecified, except that as a minimum integral types do not qualify as input iterators. Likewise, the extent to which it determines that a type does not satisfy Allocator is unspecified, except that as a minimum the member type Alloc::value_type must exist and the expression std::declval<Alloc&>().allocate(std::size_t{}) must be well-formed when treated as an unevaluated operand.

Notes

Feature-test macro	Value	Std	Comment
__cpp_lib_containers_ranges	202202L	(C++23)	Ranges-aware construction and insertion; overload (2)

Example

Run this code

#include <forward_list>
#include <vector>
 
int main()
{
    std::vector<int> v = {1, 2, 3, 4};
 
    // uses explicit deduction guide to deduce std::forward_list<int>
    std::forward_list x(v.begin(), v.end());
 
    // deduces std::forward_list<std::vector<int>::iterator>
    // first phase of overload resolution for list-initialization selects the candidate
    // synthesized from the initializer-list constructor; second phase is not performed
    // and deduction guide has no effect
    std::forward_list y{v.begin(), v.end()};
}