pub struct Extensions { /* private fields */ }
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

Create an empty Extensions.

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));

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));

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");

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());

Clear the Extensions of all inserted extensions.

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

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

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());

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);

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

Formats the value using the given formatter. Read more
Returns the “default value” for a type. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of [From]<T> for U chooses to do.

The type returned in the event of a conversion error.
Performs the conversion.
The type returned in the event of a conversion error.
Performs the conversion.