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Standard library header <tuple>

From cppreference.com
< cpp‎ | header
 
 
 

This header is part of the general utility library.

Contents

Includes

(C++20)
Three-way comparison operator support [edit]

Classes

(C++11)
implements fixed size container, which holds elements of possibly different types
(class template) [edit]
obtains the size of tuple at compile time
(class template specialization) [edit]
obtains the type of the specified element
(class template specialization) [edit]
specializes the std::uses_allocator type trait
(class template specialization) [edit]

Constants

placeholder to skip an element when unpacking a tuple using tie
(constant) [edit]

Functions

creates a tuple object of the type defined by the argument types
(function template) [edit]
creates a tuple of lvalue references or unpacks a tuple into individual objects
(function template) [edit]
creates a tuple of forwarding references
(function template) [edit]
creates a tuple by concatenating any number of tuples
(function template) [edit]
tuple accesses specified element
(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 tuple
(function template) [edit]
specializes the std::swap algorithm
(function template) [edit]
(C++17)
calls a function with a tuple of arguments
(function template) [edit]
Construct an object with a tuple of arguments
(function template) [edit]

[edit] Synopsis

#include <compare>
 
namespace std {
  // class template tuple
  template<class... Types>
    class tuple;
 
  // tuple creation functions
  inline constexpr /* unspecified */ ignore;
 
  template<class... TTypes>
    constexpr tuple<unwrap_ref_decay_t<TTypes>...> make_tuple(TTypes&&...);
 
  template<class... TTypes>
    constexpr tuple<TTypes&&...> forward_as_tuple(TTypes&&...) noexcept;
 
  template<class... TTypes>
    constexpr tuple<TTypes&...> tie(TTypes&...) noexcept;
 
  template<class... Tuples>
    constexpr tuple<CTypes...> tuple_cat(Tuples&&...);
 
  // calling a function with a tuple of arguments
  template<class F, class Tuple>
    constexpr decltype(auto) apply(F&& f, Tuple&& t);
 
  template<class T, class Tuple>
    constexpr T make_from_tuple(Tuple&& t);
 
  // tuple helper classes
  template<class T> struct tuple_size;                  // not defined
  template<class T> struct tuple_size<const T>;
 
  template<class... Types> struct tuple_size<tuple<Types...>>;
 
  template<size_t I, class T> struct tuple_element;     // not defined
  template<size_t I, class T> struct tuple_element<I, const T>;
 
  template<size_t I, class... Types>
    struct tuple_element<I, tuple<Types...>>;
 
  template<size_t I, class T>
    using tuple_element_t = typename tuple_element<I, T>::type;
 
  // element access
  template<size_t I, class... Types>
    constexpr tuple_element_t<I, tuple<Types...>>& get(tuple<Types...>&) noexcept;
  template<size_t I, class... Types>
    constexpr tuple_element_t<I, tuple<Types...>>&& get(tuple<Types...>&&) noexcept;
  template<size_t I, class... Types>
    constexpr const tuple_element_t<I, tuple<Types...>>&
      get(const tuple<Types...>&) noexcept;
  template<size_t I, class... Types>
    constexpr const tuple_element_t<I, tuple<Types...>>&&
      get(const tuple<Types...>&&) noexcept;
  template<class T, class... Types>
    constexpr T& get(tuple<Types...>& t) noexcept;
  template<class T, class... Types>
    constexpr T&& get(tuple<Types...>&& t) noexcept;
  template<class T, class... Types>
    constexpr const T& get(const tuple<Types...>& t) noexcept;
  template<class T, class... Types>
    constexpr const T&& get(const tuple<Types...>&& t) noexcept;
 
  // relational operators
  template<class... TTypes, class... UTypes>
    constexpr bool operator==(const tuple<TTypes...>&, const tuple<UTypes...>&);
  template<class... TTypes, class... UTypes>
    constexpr common_comparison_category_t</*synth-three-way-result*/<TTypes, UTypes>...>
      operator<=>(const tuple<TTypes...>&, const tuple<UTypes...>&);
 
  // allocator-related traits
  template<class... Types, class Alloc>
    struct uses_allocator<tuple<Types...>, Alloc>;
 
  // specialized algorithms
  template<class... Types>
    constexpr void
      swap(tuple<Types...>& x, tuple<Types...>& y) noexcept(/* see description */);
 
  // tuple helper classes
  template<class T>
    inline constexpr size_t tuple_size_v = tuple_size<T>::value;
}
 
// deprecated
namespace std {
  template<class T> class tuple_size<volatile T>;
  template<class T> class tuple_size<const volatile T>;
 
  template<size_t I, class T> class tuple_element<I, volatile T>;
  template<size_t I, class T> class tuple_element<I, const volatile T>;
}

[edit] Class template std::tuple

namespace std {
  template<class... Types>
  class tuple {
  public:
    // tuple construction
    constexpr explicit(/* see description */) tuple();
    constexpr explicit(/* see description */)
      tuple(const Types&...);         // only if sizeof...(Types) >= 1
    template<class... UTypes>
      constexpr explicit(/* see description */)
        tuple(UTypes&&...);           // only if sizeof...(Types) >= 1
 
    tuple(const tuple&) = default;
    tuple(tuple&&) = default;
 
    template<class... UTypes>
      constexpr explicit(/* see description */) tuple(const tuple<UTypes...>&);
    template<class... UTypes>
      constexpr explicit(/* see description */) tuple(tuple<UTypes...>&&);
 
    template<class U1, class U2>
      constexpr explicit(/* see description */)
        tuple(const pair<U1, U2>&);   // only if sizeof...(Types) == 2
    template<class U1, class U2>
      constexpr explicit(/* see description */)
        tuple(pair<U1, U2>&&);        // only if sizeof...(Types) == 2
 
    // allocator-extended constructors
    template<class Alloc>
      constexpr explicit(/* see description */)
        tuple(allocator_arg_t, const Alloc& a);
    template<class Alloc>
      constexpr explicit(/* see description */)
        tuple(allocator_arg_t, const Alloc& a, const Types&...);
    template<class Alloc, class... UTypes>
      constexpr explicit(/* see description */)
        tuple(allocator_arg_t, const Alloc& a, UTypes&&...);
    template<class Alloc>
      constexpr tuple(allocator_arg_t, const Alloc& a, const tuple&);
    template<class Alloc>
      constexpr tuple(allocator_arg_t, const Alloc& a, tuple&&);
    template<class Alloc, class... UTypes>
      constexpr explicit(/* see description */)
        tuple(allocator_arg_t, const Alloc& a, const tuple<UTypes...>&);
    template<class Alloc, class... UTypes>
      constexpr explicit(/* see description */)
        tuple(allocator_arg_t, const Alloc& a, tuple<UTypes...>&&);
    template<class Alloc, class U1, class U2>
      constexpr explicit(/* see description */)
        tuple(allocator_arg_t, const Alloc& a, const pair<U1, U2>&);
    template<class Alloc, class U1, class U2>
      constexpr explicit(/* see description */)
        tuple(allocator_arg_t, const Alloc& a, pair<U1, U2>&&);
 
    // tuple assignment
    constexpr tuple& operator=(const tuple&);
    constexpr tuple& operator=(tuple&&) noexcept(/* see description */);
 
    template<class... UTypes>
      constexpr tuple& operator=(const tuple<UTypes...>&);
    template<class... UTypes>
      constexpr tuple& operator=(tuple<UTypes...>&&);
 
    template<class U1, class U2>
      constexpr tuple& operator=(const pair<U1, U2>&); // only if sizeof...(Types) == 2
    template<class U1, class U2>
      constexpr tuple& operator=(pair<U1, U2>&&);      // only if sizeof...(Types) == 2
 
    // tuple swap
    constexpr void swap(tuple&) noexcept(/* see description */);
  };
 
  template<class... UTypes>
    tuple(UTypes...) -> tuple<UTypes...>;
  template<class T1, class T2>
    tuple(pair<T1, T2>) -> tuple<T1, T2>;
  template<class Alloc, class... UTypes>
    tuple(allocator_arg_t, Alloc, UTypes...) -> tuple<UTypes...>;
  template<class Alloc, class T1, class T2>
    tuple(allocator_arg_t, Alloc, pair<T1, T2>) -> tuple<T1, T2>;
  template<class Alloc, class... UTypes>
    tuple(allocator_arg_t, Alloc, tuple<UTypes...>) -> tuple<UTypes...>;
}