Struct PolyMap

pub struct PolyMap<K: Eq + Hash, S = RandomState> { /* private fields */ }

A key-value map that can contain varying types of values.

A single PolyMap instance can map a given key to varying types of values. Successive operations on this key must use the correct type or the operation will panic.

If you would like to store only one value of each type, use TypeMap.

Example

use polymap::PolyMap;

let mut map = PolyMap::new();

// Maps `&str` to `&str`.
map.insert("foo", "Hello, world!");

// Maps `&str` to `i32`.
map.insert("bar", 123);

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

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

Implementations

impl<K: Eq + Hash> PolyMap<K, RandomState>

pub fn new() -> PolyMap<K>

Constructs a new PolyMap.

pub fn with_capacity(n: usize) -> PolyMap<K>

Constructs a new PolyMap with space reserved for n elements.

impl<K: Eq + Hash, S: BuildHasher> PolyMap<K, S>

pub fn with_hasher(hash_builder: S) -> PolyMap<K, S>

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

pub fn clear(&mut self)

Removes all key-value pairs from the map.

pub fn contains_key<Q>(&self, k: &Q) -> bool

where K: Borrow<Q>, Q: Eq + Hash + ?Sized,

Returns whether the map contains a value corresponding to the given key. Does not make any assertions about the type of the value.

pub fn contains_key_of<Q, T: Any>(&self, k: &Q) -> bool

where K: Borrow<Q>, Q: Eq + Hash + ?Sized,

Returns whether the map contains a value corresponding to the given key whose type is the same as the given type.

Example

use polymap::PolyMap;

let mut map = PolyMap::new();

map.insert("foo", 1);
assert_eq!(false, map.contains_key_of::<_, &str>("foo"));
assert_eq!(true, map.contains_key_of::<_, i32>("foo"));

pub fn capacity(&self) -> usize

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

pub fn entry<T: Any>(&mut self, key: K) -> Entry<'_, K, T>

Returns the key’s corresponding entry in the map for in-place manipulation.

Whether the entry is occupied or vacant, the type of value that can be inserted into the returned entry is constrained to T.

Panics

If the entry exists, but the type of value differs from the one requested.

pub fn get<Q, T: Any>(&self, k: &Q) -> Option<&T>

where K: Borrow<Q>, Q: Eq + Hash + ?Sized,

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

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

Panics

If the key exists, but the type of value differs from the one requested.

pub fn get_mut<Q, T: Any>(&mut self, k: &Q) -> Option<&mut T>

where K: Borrow<Q>, Q: Eq + Hash + ?Sized,

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

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

Panics

If the key exists, but the type of value differs from the one requested.

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

Inserts a key-value pair into the map. If the key is already present, that value is returned. Otherwise, None is returned.

Panics

If the key exists, but has a value of a different type than the one given.

pub fn keys(&self) -> Keys<'_, K>

Returns an iterator visiting all keys in arbitrary order. Iterator element type is &K.

pub fn len(&self) -> usize

Returns the number of elements in the map.

pub fn is_empty(&self) -> bool

Returns whether the map is empty.

pub fn reserve(&mut self, additional: usize)

Reserves capacity for at least additional additional elements.

pub fn remove<Q, T: Any>(&mut self, k: &Q) -> Option<T>

where K: Borrow<Q>, Q: Eq + Hash + ?Sized,

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

Panics

If the key exists, but the type of value differs from the one requested.

pub fn shrink_to_fit(&mut self)

Shrinks the capacity of the map as much as possible.

Trait Implementations

impl<K: Eq + Hash + Debug, S: BuildHasher> Debug for PolyMap<K, S>

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

Formats the value using the given formatter.

impl<K: Eq + Hash, S: BuildHasher + Default> Default for PolyMap<K, S>

fn default() -> PolyMap<K, S>

Returns the “default value” for a type.