key_value_pair::key_value

`key_value_pair::key_value_pair`

Constructors.

Synopsis

template<
    class... Args>
explicit
key_value_pair(
    string_view key,
    Args&&... args); (1)

explicit
key_value_pair(
    std::pair< string_view, value > const& p,
    storage_ptr sp = {}); (2)

explicit
key_value_pair(
    std::pair< string_view, value >&& p,
    storage_ptr sp = {}); (3)

key_value_pair(
    key_value_pair const& other,
    storage_ptr sp); (4)

key_value_pair(
    key_value_pair const& other); (5)

key_value_pair(
    key_value_pair&& other) noexcept; (6)

key_value_pair(
    pilfered< key_value_pair > other) noexcept; (7)

Description

Construct a key/value pair.

(1) uses a copy of the characters of key, and constructs the value as if by value(std::forward<Args>(args)...).
(2) equivalent to key_value_pair(p.first, p.second, sp).
(3) equivalent to key_value_pair(p.first, std::move(p.second), sp).
(4) equivalent to key_value_pair(other.key(), other.value(), sp).
(5) equivalent to key_value_pair(other.key(), other.value(), other.storage()).
(6) the pair s constructed by acquiring ownership of the contents of other using move semantics.
(7) the pair is constructed by acquiring ownership of the contents of other using pilfer semantics. This is more efficient than move construction, when it is known that the moved-from object will be immediately destroyed afterwards.

With (2), (3), (4) the pair uses the memory resource of sp. With (5), (6), (7) it uses the memory resource of other.storage(). With (1) it uses whatever memory resource value(std::forward<Args>(args)...) would use. In any case the pair acquires shared ownership of its memory resource

After (6) other holds an empty key, and a null value with its current storage pointer.

After (7) other is not in a usable state and may only be destroyed.

Complexity

Constant.

Exception Safety

Strong guarantee. Calls to memory_resource::allocate may throw.

Parameters

Name Description

Name	Description
`key`	The key string to use.
`args`	Optional arguments forwarded to the `value` constructor.
`p`	A `std::pair` with the key string and `value` to construct with.
`sp`	A pointer to the `boost::container::pmr::memory_resource` to use.
`other`	Another key/value pair.

key

The key string to use.

args

Optional arguments forwarded to the value constructor.

p

A std::pair with the key string and value to construct with.

sp

A pointer to the boost::container::pmr::memory_resource to use.

other

Another key/value pair.

Exceptions

Type Thrown On

Type	Thrown On
`boost::system::system_error`	The size of the key would exceed `string::max_size`.

boost::system::system_error

The size of the key would exceed string::max_size.