Struct Extensions

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pub struct Extensions { /* private fields */ }

Available on crate feature server only.

Expand description

A type map of protocol extensions.

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

Implementations§

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impl Extensions

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pub fn new() -> Extensions

Create an empty Extensions.

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

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));

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

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));

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

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");

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

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);

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

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

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);

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

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());

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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());

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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());

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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);

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

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"));