Struct polymap::typemap::TypeMap

pub struct TypeMap<S = RandomState> { /* fields omitted */ }

A container for values of varying types.

Values contained in a TypeMap are stored uniquely according to their type. This means that, for each possible type, only one value may be stored in a single TypeMap instance.

If you would like to store multiple values of a given type, mapped to individual keys, use PolyMap.

Example

use polymap::TypeMap;

let mut map = TypeMap::new();

// Stores a `&str` value
map.insert("Hello, world!");

// Stores an `i32` value
map.insert(123);

// Gets a reference to the stored value
let &foo: &&str = map.get().unwrap();
assert_eq!(foo, "Hello, world!");

let &bar: &i32 = map.get().unwrap();
assert_eq!(bar, 123);

Methods

impl TypeMap<RandomState>

fn new() -> TypeMap

Constructs a new TypeMap.

fn with_capacity(n: usize) -> TypeMap

Constructs a new TypeMap with space reserved for n elements.

impl<S: BuildHasher> TypeMap<S>

fn with_hasher(hash_builder: S) -> TypeMap<S>

Creates an empty TypeMap which will use the given hash builder to hash keys.

fn clear(&mut self)

Removes all values from the map.

fn contains<T: Any>(&self) -> bool

Returns whether the map contains a value corresponding to the given type.

fn capacity(&self) -> usize

Returns the number of elements the map can hold without reallocating.

fn entry<T: Any>(&mut self) -> Entry<T>

Returns the type's corresponding entry in the map for in-place manipulation.

fn get<T: Any>(&self) -> Option<&T>

Returns a reference to the value corresponding to the given type.

If the type is not contained within the map, None will be returned.

fn get_mut<T: Any>(&mut self) -> Option<&mut T>

Returns a mutable reference to the value corresponding to the given type.

If the type is not contained within the map, None will be returned.

fn insert<T: Any>(&mut self, t: T) -> Option<T>

Inserts a value into the map. If a value of that type is already present, that value is returned. Otherwise, None is returned.

fn len(&self) -> usize

Returns the number of elements in the map.

fn is_empty(&self) -> bool

Returns whether the map is empty.

fn reserve(&mut self, additional: usize)

Reserves capacity for at least additional additional elements.

fn remove<T: Any>(&mut self) -> Option<T>

Removes a value from the map, returning the value if one existed.

fn shrink_to_fit(&mut self)

Shrinks the capacity of the map as much as possible.

Trait Implementations

impl<S> Debug for TypeMap<S>

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

Formats the value using the given formatter.

impl<S: BuildHasher + Default> Default for TypeMap<S>

fn default() -> TypeMap<S>

Returns the "default value" for a type.