Struct typemap_rev::TypeMap

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pub struct TypeMap<S: ?Sized = DefaultStorage>(_);

Expand description

TypeMap is a simple abstraction around the standard library’s HashMap type, where types are its keys. This allows for statically-checked value retrieval.

Implementations

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impl TypeMap

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pub fn new() -> Self

Creates a new instance of TypeMap.

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impl<S: ?Sized + Any + Send + Sync> TypeMap<S>

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pub fn custom() -> Self

Creates a new instance of TypeMap with a custom storage type.

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pub fn len(&self) -> usize

Returns the amount of entries in the map.

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pub fn is_empty(&self) -> bool

Returns an indicator whether the map is empty (no entries).

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pub fn clear(&mut self)

Clears all entries in the map.

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pub fn contains_key<T>(&self) -> boolwhere
T: TypeMapKey,

Returns true if the map contains a value for the specified TypeMapKey.

use typemap_rev::{TypeMap, TypeMapKey};

struct Number;

impl TypeMapKey for Number {
    type Value = i32;
}

let mut map = TypeMap::new();
assert!(!map.contains_key::<Number>());
map.insert::<Number>(42);
assert!(map.contains_key::<Number>());

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pub fn insert<T>(&mut self, value: T::Value)where
T: TypeMapKey,
T::Value: IntoBox<S>,

Inserts a new value based on its TypeMapKey. If the value has been already inserted, it will be overwritten with the new value.

use typemap_rev::{TypeMap, TypeMapKey};

struct Number;

impl TypeMapKey for Number {
    type Value = i32;
}

let mut map = TypeMap::new();
map.insert::<Number>(42);
// Overwrite the value of `Number` with -42.
map.insert::<Number>(-42);

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pub fn entry<T>(&mut self) -> Entry<'_, T, S>where
T: TypeMapKey,
T::Value: IntoBox<S>,

Retrieve the entry based on its TypeMapKey

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pub fn get<T>(&self) -> Option<&T::Value>where
T: TypeMapKey,
T::Value: IntoBox<S>,

Retrieve a reference to a value based on its TypeMapKey. Returns None if it couldn’t be found.

use typemap_rev::{TypeMap, TypeMapKey};

struct Number;

impl TypeMapKey for Number {
    type Value = i32;
}

let mut map = TypeMap::new();
map.insert::<Number>(42);

assert_eq!(*map.get::<Number>().unwrap(), 42);

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pub fn get_mut<T>(&mut self) -> Option<&mut T::Value>where
T: TypeMapKey,
T::Value: IntoBox<S>,

Retrieve a mutable reference to a value based on its TypeMapKey. Returns None if it couldn’t be found.

use typemap_rev::{TypeMap, TypeMapKey};

struct Number;

impl TypeMapKey for Number {
    type Value = i32;
}

let mut map = TypeMap::new();
map.insert::<Number>(42);

assert_eq!(*map.get::<Number>().unwrap(), 42);
*map.get_mut::<Number>().unwrap() -= 42;
assert_eq!(*map.get::<Number>().unwrap(), 0);

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pub fn remove<T>(&mut self) -> Option<T::Value>where
T: TypeMapKey,
T::Value: IntoBox<S>,

Removes a value from the map based on its TypeMapKey.

Returns a boolean indicating whether the value existed prior to its removal.

use typemap_rev::{TypeMap, TypeMapKey};

struct Text;

impl TypeMapKey for Text {
    type Value = String;
}

let mut map = TypeMap::new();
map.insert::<Text>(String::from("Hello TypeMap!"));
assert!(map.remove::<Text>().is_some());
assert!(map.get::<Text>().is_none());