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Difference between revisions of "cpp/header/utility"

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Revision as of 09:22, 25 November 2016

 
C++
 
Standard library headers
General utilities
<any> (C++17)
<bitset>
<bit> (C++20)
<charconv> (C++17)
<expected> (C++23)
<format> (C++20)
<functional>
<optional> (C++17)
<tuple> (C++11)
<typeindex> (C++11)
<utility>
<variant> (C++17)
Containers
<array> (C++11)
<deque>
<flat_map> (C++23)
<flat_set> (C++23)
<forward_list> (C++11)
<inplace_vector> (C++26)   
<list>
<map>
<mdspan> (C++23)
<queue>
<set>
<span> (C++20)
<stack>
<unordered_map> (C++11)
<unordered_set> (C++11)
<vector>
Iterators
<iterator>
Ranges
<generator> (C++23)
<ranges> (C++20)
 

This header is part of the general utility library.

Contents

Includes

<initializer_list>(C++11)

Namespaces

rel_ops Provide automatic comparison operators
Defined in namespace std::rel_ops
(deprecated in C++20)
 automatically generates comparison operators based on user-defined operator== and operator<
(function template) [edit]

Functions

 swaps the values of two objects
(function template) [edit]
(C++14)
 replaces the argument with a new value and returns its previous value
(function template) [edit]
(C++11)
 forwards a function argument and use the type template argument to preserve its value category
(function template) [edit]
(C++11)
 converts the argument to an xvalue
(function template) [edit]
(C++11)
 converts the argument to an xvalue if the move constructor does not throw
(function template) [edit]
(C++17)
 obtains a reference to const to its argument
(function template) [edit]
(C++11)
 obtains a reference to an object of the template type argument for use in an unevaluated context
(function template) [edit]
creates a pair object of type, determined by the argument types
(function template) [edit]
(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(C++20)
 lexicographically compares the values in the pair
(function template) [edit]
(C++11)
 specializes the std::swap algorithm
(function template) [edit]
(C++11)
 accesses an element of a pair
(function template) [edit]

Classes

 implements binary tuple, i.e. a pair of values
(class template) [edit]
(C++14)
 implements compile-time sequence of integers
(class template) [edit]

Helpers

(C++11)
 tag type used to select correct function overload for piecewise construction
(class) [edit]
(C++11)
 piecewise construction tag
(tag)[edit]
(C++17)
 in-place construction tag
(tag)[edit]
Forward declarations
(C++11)
 implements fixed size container, which holds elements of possibly different types
(class template) [edit]

Synopsis

#include <initializer_list>
namespace std {
  // operators:
  namespace rel_ops {
    template<class T> bool operator!=(const T&, const T&);
    template<class T> bool operator> (const T&, const T&);
    template<class T> bool operator<=(const T&, const T&);
    template<class T> bool operator>=(const T&, const T&);
  }
  // swap:
  template <class T>
  void swap(T& a, T& b) noexcept(/*see definition*/ );
  template <class T, size_t N>
  void swap(T (&a)[N], T (&b)[N]) noexcept(is_nothrow_swappable_v<T>);
 
  // exchange:
  template <class T, class U=T> T exchange(T& obj, U&& new_val);
 
  // forward/move:
  template <class T>
  constexpr T&& forward(remove_reference_t<T>& t) noexcept;
  template <class T>
  constexpr T&& forward(remove_reference_t<T>&& t) noexcept;
  template <class T>
  constexpr remove_reference_t<T>&& move(T&&) noexcept;
  template <class T>
  constexpr conditional_t<!is_nothrow_move_constructible_v<T>
                          && is_copy_constructible_v<T>, const T&, T&&>
  move_if_noexcept(T& x) noexcept;
 
  // as_const:
  template <class T> constexpr add_const_t<T>& as_const(T& t) noexcept;
  template <class T> void as_const(const T&&) = delete;
 
  // declval:
  template <class T>
  add_rvalue_reference_t<T> declval() noexcept; // as unevaluated operand
 
  // Compile-time integer sequences
  template<class T, T...> struct integer_sequence;
  template<size_t... I>
  using index_sequence = integer_sequence<size_t, I...>;
  template<class T, T N>
  using make_integer_sequence = integer_sequence<T, /*see definition*/ >;
  template<size_t N>
  using make_index_sequence = make_integer_sequence<size_t, N>;
  template<class... T>
  using index_sequence_for = make_index_sequence<sizeof...(T)>;
 
  // pairs:
  template <class T1, class T2> struct pair;
 
  // pair specialized algorithms:
  template <class T1, class T2>
  constexpr bool operator==(const pair<T1, T2>&, const pair<T1, T2>&);
  template <class T1, class T2>
  constexpr bool operator< (const pair<T1, T2>&, const pair<T1, T2>&);
  template <class T1, class T2>
  constexpr bool operator!=(const pair<T1, T2>&, const pair<T1, T2>&);
  template <class T1, class T2>
  constexpr bool operator> (const pair<T1, T2>&, const pair<T1, T2>&);
  template <class T1, class T2>
  constexpr bool operator>=(const pair<T1, T2>&, const pair<T1, T2>&);
  template <class T1, class T2>
  constexpr bool operator<=(const pair<T1, T2>&, const pair<T1, T2>&);
  template <class T1, class T2>
  void swap(pair<T1, T2>& x, pair<T1, T2>& y) noexcept(noexcept(x.swap(y)));
  template <class T1, class T2>
  constexpr /*see definition*/ make_pair(T1&&, T2&&);
 
  // tuple-like access to pair:
  template <class T> class tuple_size;
  template <size_t I, class T> class tuple_element;
  template <class T1, class T2> struct tuple_size<pair<T1, T2>>;
  template <class T1, class T2> struct tuple_element<0, pair<T1, T2>>;
  template <class T1, class T2> struct tuple_element<1, pair<T1, T2>>;
  template<size_t I, class T1, class T2>
  constexpr tuple_element_t<I, pair<T1, T2>>& get(pair<T1, T2>&) noexcept;
  template<size_t I, class T1, class T2>
  constexpr tuple_element_t<I, pair<T1, T2>>&& get(pair<T1, T2>&&) noexcept;
  template<size_t I, class T1, class T2>
  constexpr const tuple_element_t<I, pair<T1, T2>>& get(const pair<T1, T2>&) noexcept;
  template<size_t I, class T1, class T2>
  constexpr const tuple_element_t<I, pair<T1, T2>>&& get(const pair<T1, T2>&&) noexcept;
  template <class T, class U>
  constexpr T& get(pair<T, U>& p) noexcept;
  template <class T, class U>
  constexpr const T& get(const pair<T, U>& p) noexcept;
  template <class T, class U>
  constexpr T&& get(pair<T, U>&& p) noexcept;
  template <class T, class U>
  constexpr const T&& get(const pair<T, U>&& p) noexcept;
  template <class T, class U>
  constexpr T& get(pair<U, T>& p) noexcept;
  template <class T, class U>
  constexpr const T& get(const pair<U, T>& p) noexcept;
  template <class T, class U>
  constexpr T&& get(pair<U, T>&& p) noexcept;
  template <class T, class U>
  constexpr const T&& get(const pair<U, T>&& p) noexcept;
 
  // pair piecewise construction
  struct piecewise_construct_t { };
  constexpr piecewise_construct_t piecewise_construct{};
  template <class... Types> class tuple; // defined in <tuple>
 
  // in-place construction
  struct in_place_tag {
    in_place_tag() = delete;
  };
  using in_place_t = in_place_tag(&)(unspecified );
  template <class T>
  using in_place_type_t = in_place_tag(&)(unspecified <T>);
  template <size_t I>
  using in_place_index_t = in_place_tag(&)(unspecified <I>);
  in_place_tag in_place(unspecified );
  template <class T>
  in_place_tag in_place(unspecified <T>);
  template <size_t I>
  in_place_tag in_place(unspecified <I>);
}

Class template std::integer_sequence 

namespace std {
  template<class T, T... I>
  struct integer_sequence {
    using value_type = T;
    static constexpr size_t size() noexcept { return sizeof...(I); }
  };
}

Class std::pair

namespace std {
  template <class T1, class T2>
  struct pair {
    using first_type = T1;
    using second_type = T2;
    T1 first;
    T2 second;
    pair(const pair&) = default;
    pair(pair&&) = default;
    constexpr pair();
    /*conditionally-explicit*/ constexpr pair(const T1& x, const T2& y);
    template<class U, class V>
    /*conditionally-explicit*/  constexpr pair(U&& x, V&& y);
    template<class U, class V>
    /*conditionally-explicit*/  constexpr pair(const pair<U, V>& p);
    template<class U, class V>
    /*conditionally-explicit*/  constexpr pair(pair<U, V>&& p);
    template <class... Args1, class... Args2>
    pair(piecewise_construct_t, tuple<Args1...> first_args, tuple<Args2...> second_args);
    pair& operator=(const pair& p);
    template<class U, class V> pair& operator=(const pair<U, V>& p);
    pair& operator=(pair&& p) noexcept(/*see definition*/ );
    template<class U, class V> pair& operator=(pair<U, V>&& p);
    void swap(pair& p) noexcept(/*see definition*/);
  };
}

See also

<tuple> Defines std::tuple
Utility library
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