bsl::pair

Synopsis

Declared in <bslstl_pair.h>

template<
    class T1,
    class T2>
class pair
    : public Pair_First<T1>
    , public Pair_Second<T2>

Description

The class template pair provides a pair of public data members, first and second, of type T1 and T2 respectively. If either T1 or T2 uses bslma::Allocator for memory management, then provide an optional bslma::Allocator argument for each constructor, to be passed through to the constructors of first and/or second as appropriate. The interface to this class is identical to the standard std::pair except for the addition of the allocators. Note that the implementation of this class provides first and second through multiple base classes in order to simplify construction of each member when allowing for the various rules for passing allocators in C++11.

Base Classes

Name	Description
`Pair_First<T1>`	Component-private base holding and constructing a pair's `first` member.
`Pair_Second<T2>`	Component-private base holding and constructing a pair's `second` member.

Type Aliases

Name	Description
`first_type`	This `typedef` is an alias to the type of the `first` data member.
`second_type`	This `typedef` is an alias to the type of the `second` data member.

Member Functions

Name	Description
`pair` [constructor]	Constructors
`operator=`	Assignment operators
`swap`	Swap the value of this pair with the value of the specified `other` pair by applying `swap` to each of the `first` and `second` pair fields.
`operator std::tuple<PARAM_1&, PARAM_2&>`	Return an `std::tuple` object, holding references that provide modifiable access to the members of this object.
`operator std::tuple<PARAM_1&, decltype(std::ignore)&>`	Convert to an `std::tuple` whose second element is `std::ignore`.
`operator std::tuple<decltype(std::ignore)&, PARAM_2&>`	Convert to an `std::tuple` whose first element is `std::ignore`.
`operator std::tuple<decltype(std::ignore)&, decltype(std::ignore)&>`	Convert to an `std::tuple` whose elements are both `std::ignore`.

Using Declarations

Name	Description
`first`	Bring the `first` data member from `FirstBase` into scope.
`second`	Bring the `second` data member from `SecondBase` into scope.

Protected Data Members

Name	Description
`first`	First element of the pair.
`second`	Second element of the pair.

Deduction Guides

Name	Description
`pair<T1, T2>`	Deduce the specified types `T1` and `T2` from the corresponding template parameters of the `std::pair` supplied to the constructor of `pair`.
`pair<T1, T2>`	Deduce the specified types `T1` and `T2` from the corresponding types supplied to the constructor of `pair`.
`pair<T1, T2>`	Deduce `T1` and `T2` from the `bsl::pair` and allocator passed to `pair`.
`pair<T1, T2>`	Deduce `T1` and `T2` from the `std::pair` and allocator passed to `pair`.
`pair<T1, T2>`	Deduce `T1` and `T2` from the values and allocator passed to `pair`.

Non-Member Functions

Name	Description
`get`	Return a modifiable reference to the `INDEX`th element of `p`.
`get`	Return a non-modifiable rvalue reference to the element of `p` of `TYPE`.
`get`	Return a non-modifiable reference to the `INDEX`th element of `p`.
`get`	Return a non-modifiable reference to the element of `p` having type `TYPE`.
`get`	Return a modifiable reference to the element of `p` having type `TYPE`.
`get`	Return a modifiable rvalue reference to the `INDEX`th element of `p`.
`get`	Return a modifiable rvalue reference to the element of `p` of type `TYPE`.
`operator<=>`	Compare the specified `lhs` and `rhs` pairs lexicographically.
`operator==`	Return `true` if the specified `lhs` and `rhs` pairs have the same value.
`swap`	Swap the values of the specified `a` and `b` pairs.