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deductionguidesforstd::map(3)  C++ Standard Libary deductionguidesforstd::map(3)

NAME
     deductionguidesforstd::map - deductionguidesforstd::map

Synopsis
	Defined in header <map>
	template< class InputIt,

		  class Comp = std::less<iter_key_t<InputIt>>,
		  class Alloc =
	std::allocator<iter_to_alloc_t<InputIt>> >		      (1) (since
     C++17)
	map( InputIt, InputIt, Comp = Comp(), Alloc = Alloc() )

	    -> map<iter_key_t<InputIt>, iter_val_t<InputIt>, Comp,
	Alloc>;
	template< class Key,

		  class T,
		  class Comp = std::less<Key>,
		  class Alloc = std::allocator<std::pair<const Key,   (2) (since
     C++17)
	T>> >
	map( std::initializer_list<std::pair<Key, T>>, Comp = Comp(),
	Alloc = Alloc() )

	    -> map<Key, T, Comp, Alloc>;
	template< class InputIt, class Alloc >

	map( InputIt, InputIt, Alloc )				      (3) (since
     C++17)
	    -> map<iter_key_t<InputIt>, iter_val_t<InputIt>,

		   std::less<iter_key_t<InputIt>>, Alloc>;
	template< class Key, class T, class Alloc >

	map( std::initializer_list<std::pair<Key, T>>, Alloc )	      (4) (since
     C++17)

	    -> map<Key, T, std::less<Key>, Alloc>;
	template< ranges::input_range R, class Compare =
	std::less<range_key_t<R>,

		  class Alloc = std::allocator<range_to_alloc_t<R>> >
	map( std::from_range_t, R&&, Compare = Compare(), Alloc =     (5) (since
     C++23)
	Alloc() )

	    -> map<range_key_t<R>, range_mapped_t<R>, Compare,
	Alloc>;
	template< ranges::input_range R, class Alloc >

	map( std::from_range_t, R&&, Alloc )			      (6) (since
     C++23)

	    -> map<range_key_t<R>, range_mapped_t<R>,
	std::less<range_key_t<R>>, Alloc>;
	Exposition-only helper type aliases
	template< class InputIter >

	using iter_val_t =						  (expo-
     sition only*)

	    typename std::iterator_traits<InputIter>::value_type;
	template< class InputIter >

	using iter_key_t =						  (expo-
     sition only*)

	    std::remove_const_t< std::tuple_element_t<0,
	iter_val_t<InputIter>>>;
	template< class InputIter >

	using iter_mapped_t =						  (expo-
     sition only*)

	    std::tuple_element_t<1, iter_val_t<InputIter>>;
	template< class InputIter >

	using iter_to_alloc_t =
	    std::pair<std::add_const_t<tuple_element_t<0,		  (expo-
     sition only*)
	iter_val_t<InputIter>>>,

		      std::tuple_element_t<1,
	iter_val_t<InputIter>>>;
	template< ranges::input_range Range >

	using range_key_t =						  (since
     C++23)
									  (expo-
     sition only*)
	    std::remove_const_t<typename
	ranges::range_value_t<Range>::first_type>;
	template< ranges::input_range Range >
									  (since
     C++23)
	using range_mapped_t =						  (expo-
     sition only*)

	    typename ranges::range_value_t<Range>::second_type;
	template< ranges::input_range Range >

	using range_to_alloc_t =
	    std::pair<std::add_const_t<typename 			  (since
     C++23)
	ranges::range_value_t<Range>::first_type>,			  (expo-
     sition only*)

		      typename
	ranges::range_value_t<Range>::second_type>;

	1-4) These deduction guides are provided for map to allow deduction from
     an iterator
	range (overloads (1,3)) and std::initializer_list (overloads (2,4)).
	5,6) These deduction guides are provided for map to allow deduction from
     a
	std::from_range_t tag and an input_range.

	These  overloads participate in overload resolution only if InputIt sat-
     isfies
	LegacyInputIterator, Alloc satisfies Allocator, and Comp does  not  sat-
     isfy Allocator.

	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		    Feature
	__cpp_lib_containers_ranges 202202L  (C++23)  Ranges-aware  construction
     and insertion;
						    overload (5,6)

Example
     // Run this code

      #include <map>

      int main()
      {
	  // std::map m1 = {{"foo", 1}, {"bar", 2}};
	      // Error: braced-init-list has no type; cannot deduce
	      // pair<Key, T> from {"foo", 1} or {"bar", 2}

	  std::map m1 = {std::pair{"foo", 2}, {"bar", 3}}; // guide #2
	  std::map m2(m1.begin(), m1.end()); // guide #1
      }

	Defect reports

	The  following	behavior-changing  defect  reports were applied retroac-
     tively to
	previously published C++ standards.

	   DR	 Applied to	      Behavior as published		 Correct
     behavior
	LWG  3025  C++17       initializer-list  guides  take		     use
     std::pair<Key, T>
			    std::pair<const Key, T>

http://cppreference.com 	   2024.06.10	   deductionguidesforstd::map(3)
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