Struct Extensions

pub struct Extensions { /* private fields */ }

A type map of protocol extensions.

Extensions can be used by Request and Response to store extra data derived from the underlying protocol.

Implementations

impl Extensions

pub fn new() -> Extensions

Create an empty Extensions.

pub fn insert<T: Clone + Send + Sync + 'static>(&mut self, val: T) -> Option<T>

Insert a type into this Extensions.

If a extension of this type already existed, it will be returned.

Example

let mut ext = Extensions::new();
assert!(ext.insert(5i32).is_none());
assert!(ext.insert(4u8).is_none());
assert_eq!(ext.insert(9i32), Some(5i32));

pub fn get<T: Send + Sync + 'static>(&self) -> Option<&T>

Get a reference to a type previously inserted on this Extensions.

Example

let mut ext = Extensions::new();
assert!(ext.get::<i32>().is_none());
ext.insert(5i32);

assert_eq!(ext.get::<i32>(), Some(&5i32));

pub fn get_mut<T: Send + Sync + 'static>(&mut self) -> Option<&mut T>

Get a mutable reference to a type previously inserted on this Extensions.

Example

let mut ext = Extensions::new();
ext.insert(String::from("Hello"));
ext.get_mut::<String>().unwrap().push_str(" World");

assert_eq!(ext.get::<String>().unwrap(), "Hello World");

pub fn get_or_insert<T: Clone + Send + Sync + 'static>( &mut self, value: T, ) -> &mut T

Get a mutable reference to a type, inserting value if not already present on this Extensions.

Example

let mut ext = Extensions::new();
*ext.get_or_insert(1i32) += 2;

assert_eq!(*ext.get::<i32>().unwrap(), 3);

pub fn get_or_insert_with<T: Clone + Send + Sync + 'static, F: FnOnce() -> T>( &mut self, f: F, ) -> &mut T

Get a mutable reference to a type, inserting the value created by f if not already present on this Extensions.

Example

let mut ext = Extensions::new();
*ext.get_or_insert_with(|| 1i32) += 2;

assert_eq!(*ext.get::<i32>().unwrap(), 3);

pub fn get_or_insert_default<T: Default + Clone + Send + Sync + 'static>( &mut self, ) -> &mut T

Get a mutable reference to a type, inserting the type’s default value if not already present on this Extensions.

Example

let mut ext = Extensions::new();
*ext.get_or_insert_default::<i32>() += 2;

assert_eq!(*ext.get::<i32>().unwrap(), 2);

pub fn remove<T: Send + Sync + 'static>(&mut self) -> Option<T>

Remove a type from this Extensions.

If a extension of this type existed, it will be returned.

Example

let mut ext = Extensions::new();
ext.insert(5i32);
assert_eq!(ext.remove::<i32>(), Some(5i32));
assert!(ext.get::<i32>().is_none());

pub fn clear(&mut self)

Clear the Extensions of all inserted extensions.

Example

let mut ext = Extensions::new();
ext.insert(5i32);
ext.clear();

assert!(ext.get::<i32>().is_none());

pub fn is_empty(&self) -> bool

Check whether the extension set is empty or not.

Example

let mut ext = Extensions::new();
assert!(ext.is_empty());
ext.insert(5i32);
assert!(!ext.is_empty());

pub fn len(&self) -> usize

Get the numer of extensions available.

Example

let mut ext = Extensions::new();
assert_eq!(ext.len(), 0);
ext.insert(5i32);
assert_eq!(ext.len(), 1);

pub fn extend(&mut self, other: Self)

Extends self with another Extensions.

If an instance of a specific type exists in both, the one in self is overwritten with the one from other.

Example

let mut ext_a = Extensions::new();
ext_a.insert(8u8);
ext_a.insert(16u16);

let mut ext_b = Extensions::new();
ext_b.insert(4u8);
ext_b.insert("hello");

ext_a.extend(ext_b);
assert_eq!(ext_a.len(), 3);
assert_eq!(ext_a.get::<u8>(), Some(&4u8));
assert_eq!(ext_a.get::<u16>(), Some(&16u16));
assert_eq!(ext_a.get::<&'static str>().copied(), Some("hello"));

Trait Implementations

impl Clone for Extensions

fn clone(&self) -> Extensions

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Extensions

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Extensions

fn default() -> Extensions

Returns the “default value” for a type.

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 8 bytes