Struct Labels 

pub struct Labels { /* private fields */ }

A collections of assigned Labels

Labels can be used to store extra data associated with running tasks.

Implementations

impl Labels

pub fn new() -> Labels

Create an empty Labels.

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

Insert a type into this Labels.

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

Example

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

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

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

Example

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

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

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

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

Example

let mut ext = Labels::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 + 'static>(&mut self, value: T) -> &mut T

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

Example

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

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

pub fn get_or_insert_with<T: Clone + '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 Labels.

Example

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

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

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

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

Example

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

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

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

Remove a type from this Labels.

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

Example

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

pub fn clear(&mut self)

Clear all inserted labels

Example

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

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

pub fn is_empty(&self) -> bool

Check whether the label set is empty or not.

Example

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

pub fn len(&self) -> usize

Get the number of Labels available.

Example

let mut ext = Labels::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 Labels.

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 = Labels::new();
ext_a.insert(8u8);
ext_a.insert(16u16);

let mut ext_b = Labels::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 Labels

fn clone(&self) -> Labels

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Labels

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

Formats the value using the given formatter.

impl Default for Labels

fn default() -> Labels

Returns the “default value” for a type.