Struct nummap::NumMap

pub struct NumMap<K, V, S = RandomState>(_)
 where
    V: Number;

A map of numbers where all keys are considered mapped but 0 values are not stored.

Methods

impl<K, V> NumMap<K, V, RandomState> where
    K: Hash + Eq,
    V: Number, 

pub fn new() -> Self

Creates an empty NumMap.

The hash map is initially created with a capacity of 0, so it will not allocate until it is first inserted into.

Examples

use nummap::NumMap;
 
let mut map: NumMap<&str, i32> = NumMap::new();

pub fn with_capacity(capactiy: usize) -> Self

Creates an empty NumMap with the specified capacity.

The NumMap will be able to hold at least capacity elements without reallocating. If capacity is 0, the hash map will not allocate.

Examples

use nummap::NumMap;
 
let map: NumMap<&str, i32> = NumMap::with_capacity(10);

impl<K, V, S> NumMap<K, V, S> where
    V: Number, 

Important traits for Iter<'a, K, V>

impl<'a, K: 'a, V: 'a> Iterator for Iter<'a, K, V> where
    V: Number,  type Item = (&'a K, V);

pub fn iter(&self) -> Iter<K, V>

An iterator over all the key/value pairs present in this NumMap.

impl<K, V, S> NumMap<K, V, S> where
    K: Eq + Hash,
    V: Number,
    S: BuildHasher, 

pub fn with_hasher(hash_builder: S) -> Self

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

The created map has the default initial capacity.

Examples

use nummap::NumMap;
use std::collections::hash_map::RandomState;
 
let s = RandomState::new();
let mut map = NumMap::<i32, i32,>::with_hasher(s);
 
map.set(1, 2);

Warnings

hash_builder is normally randomly generated, and is designed to allow NumMaps to be resistant to attacks that cause many collisions and very poor performance. Setting it manually using this function can expose a DoS attack vector.

pub fn with_capacity_and_hasher(capacity: usize, hash_builder: S) -> Self

Creates an empty NumMap with the specified capacity, using hash_builder to hash the keys.

The hash map will be able to hold at least capacity elements without reallocating. If capacity is 0, the hash map will not allocate.

Examples

use nummap::NumMap;
use std::collections::hash_map::RandomState;
 
let s = RandomState::new();
let mut map = NumMap::<i32, i32,>::with_capacity_and_hasher(10, s);
 
map.set(1, 2);

Warning

hash_builder is normally randomly generated, and is designed to allow NumMaps to be resistant to attacks that cause many collisions and very poor performance. Setting it manually using this function can expose a DoS attack vector.

pub fn get<Q: ?Sized>(&self, k: &Q) -> V where
    K: Borrow<Q>,
    Q: Hash + Eq, 

Returns the value mapped to the corresponding key.

Examples

use nummap::NumMap;
 
let mut map = NumMap::<i32, i32,>::new();
 
map.set(1, 2);
assert_eq!(map.get(&1), 2);
assert_eq!(map.get(&2), 0);

pub fn set(&mut self, k: K, v: V) -> V

Updates the value mapped to the corresponding key and returns the old value.

Examples

use nummap::NumMap;
 
let mut map = NumMap::<i32, i32,>::new();
 
assert_eq!(map.set(1, 2), 0);
assert_eq!(map.set(1, 0), 2);

pub fn insert(&mut self, k: K, v: V::NonZero) -> V

Updates the value mapped to the corresponding key and returns the old value.

Examples

use nummap::NumMap;
use std::num::NonZeroU32;
 
let mut map = NumMap::<u32, u32,>::new();
let two = NonZeroU32::new(2,).unwrap();
 
assert_eq!(map.insert(1, two), 0);

pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> V where
    K: Borrow<Q>,
    Q: Eq + Hash, 

Removes and returns the value mapped to the corresponding key.

Examples

use nummap::NumMap;
 
let mut map = NumMap::<i32, i32,>::new();
 
assert_eq!(map.remove(&1), 0);
assert_eq!(map.set(1, 2), 0);
assert_eq!(map.remove(&1), 2);

pub fn remove_entry(&mut self, k: K) -> (K, V)

Removes and returns both the key and the value mapped to the key.

Examples

use nummap::NumMap;
 
let mut map = NumMap::<i32, i32,>::new();
 
assert_eq!(map.remove_entry(1), (1, 0,));
assert_eq!(map.set(1, 2), 0);
assert_eq!(map.remove_entry(1), (1, 2,));

pub fn retain<F>(&mut self, f: F) where
    F: FnMut(&K, V) -> bool, 

Retains only the elements specified by the predicate.

In other words, remove all pairs (k, v) such that f(&k,&mut v) returns false.

Examples

use nummap::NumMap;
 
let mut map: NumMap<i32, i32> = (0..8).map(|x|(x, x*10)).collect();
 
map.retain(|&k, _| k % 2 == 1);
assert_eq!(map.len(), 4);

Methods from Deref<Target = HashMap<K, V::NonZero, S>>

pub fn capacity(&self) -> usize

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

This number is a lower bound; the HashMap<K, V> might be able to hold more, but is guaranteed to be able to hold at least this many.

Examples

use std::collections::HashMap;
let map: HashMap<i32, i32> = HashMap::with_capacity(100);
assert!(map.capacity() >= 100);

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

An iterator visiting all keys in arbitrary order. The iterator element type is &'a K.

Examples

use std::collections::HashMap;

let mut map = HashMap::new();
map.insert("a", 1);
map.insert("b", 2);
map.insert("c", 3);

for key in map.keys() {
    println!("{}", key);
}

pub fn values(&self) -> Values<K, V>

An iterator visiting all values in arbitrary order. The iterator element type is &'a V.

Examples

use std::collections::HashMap;

let mut map = HashMap::new();
map.insert("a", 1);
map.insert("b", 2);
map.insert("c", 3);

for val in map.values() {
    println!("{}", val);
}

pub fn values_mut(&mut self) -> ValuesMut<K, V>

An iterator visiting all values mutably in arbitrary order. The iterator element type is &'a mut V.

Examples

use std::collections::HashMap;

let mut map = HashMap::new();

map.insert("a", 1);
map.insert("b", 2);
map.insert("c", 3);

for val in map.values_mut() {
    *val = *val + 10;
}

for val in map.values() {
    println!("{}", val);
}

pub fn iter(&self) -> Iter<K, V>

An iterator visiting all key-value pairs in arbitrary order. The iterator element type is (&'a K, &'a V).

Examples

use std::collections::HashMap;

let mut map = HashMap::new();
map.insert("a", 1);
map.insert("b", 2);
map.insert("c", 3);

for (key, val) in map.iter() {
    println!("key: {} val: {}", key, val);
}

pub fn iter_mut(&mut self) -> IterMut<K, V>

An iterator visiting all key-value pairs in arbitrary order, with mutable references to the values. The iterator element type is (&'a K, &'a mut V).

Examples

use std::collections::HashMap;

let mut map = HashMap::new();
map.insert("a", 1);
map.insert("b", 2);
map.insert("c", 3);

// Update all values
for (_, val) in map.iter_mut() {
    *val *= 2;
}

for (key, val) in &map {
    println!("key: {} val: {}", key, val);
}

pub fn len(&self) -> usize

Returns the number of elements in the map.

Examples

use std::collections::HashMap;

let mut a = HashMap::new();
assert_eq!(a.len(), 0);
a.insert(1, "a");
assert_eq!(a.len(), 1);

pub fn is_empty(&self) -> bool

Returns true if the map contains no elements.

Examples

use std::collections::HashMap;

let mut a = HashMap::new();
assert!(a.is_empty());
a.insert(1, "a");
assert!(!a.is_empty());

pub fn drain(&mut self) -> Drain<K, V>

Clears the map, returning all key-value pairs as an iterator. Keeps the allocated memory for reuse.

Examples

use std::collections::HashMap;

let mut a = HashMap::new();
a.insert(1, "a");
a.insert(2, "b");

for (k, v) in a.drain().take(1) {
    assert!(k == 1 || k == 2);
    assert!(v == "a" || v == "b");
}

assert!(a.is_empty());

pub fn clear(&mut self)

Clears the map, removing all key-value pairs. Keeps the allocated memory for reuse.

Examples

use std::collections::HashMap;

let mut a = HashMap::new();
a.insert(1, "a");
a.clear();
assert!(a.is_empty());

pub fn hasher(&self) -> &S

Returns a reference to the map's BuildHasher.

Examples

use std::collections::HashMap;
use std::collections::hash_map::RandomState;

let hasher = RandomState::new();
let map: HashMap<i32, i32> = HashMap::with_hasher(hasher);
let hasher: &RandomState = map.hasher();

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

Reserves capacity for at least additional more elements to be inserted in the HashMap. The collection may reserve more space to avoid frequent reallocations.

Panics

Panics if the new allocation size overflows usize.

Examples

use std::collections::HashMap;
let mut map: HashMap<&str, i32> = HashMap::new();
map.reserve(10);

pub fn try_reserve(
    &mut self,
    additional: usize
) -> Result<(), CollectionAllocErr>

🔬 This is a nightly-only experimental API. (try_reserve)

new API

Tries to reserve capacity for at least additional more elements to be inserted in the given HashMap<K,V>. The collection may reserve more space to avoid frequent reallocations.

Errors

If the capacity overflows, or the allocator reports a failure, then an error is returned.

Examples

#![feature(try_reserve)]
use std::collections::HashMap;
let mut map: HashMap<&str, isize> = HashMap::new();
map.try_reserve(10).expect("why is the test harness OOMing on 10 bytes?");

pub fn shrink_to_fit(&mut self)

Shrinks the capacity of the map as much as possible. It will drop down as much as possible while maintaining the internal rules and possibly leaving some space in accordance with the resize policy.

Examples

use std::collections::HashMap;

let mut map: HashMap<i32, i32> = HashMap::with_capacity(100);
map.insert(1, 2);
map.insert(3, 4);
assert!(map.capacity() >= 100);
map.shrink_to_fit();
assert!(map.capacity() >= 2);

pub fn shrink_to(&mut self, min_capacity: usize)

🔬 This is a nightly-only experimental API. (shrink_to)

new API

Shrinks the capacity of the map with a lower limit. It will drop down no lower than the supplied limit while maintaining the internal rules and possibly leaving some space in accordance with the resize policy.

Panics if the current capacity is smaller than the supplied minimum capacity.

Examples

#![feature(shrink_to)]
use std::collections::HashMap;

let mut map: HashMap<i32, i32> = HashMap::with_capacity(100);
map.insert(1, 2);
map.insert(3, 4);
assert!(map.capacity() >= 100);
map.shrink_to(10);
assert!(map.capacity() >= 10);
map.shrink_to(0);
assert!(map.capacity() >= 2);

pub fn entry(&mut self, key: K) -> Entry<K, V>

Gets the given key's corresponding entry in the map for in-place manipulation.

Examples

use std::collections::HashMap;

let mut letters = HashMap::new();

for ch in "a short treatise on fungi".chars() {
    let counter = letters.entry(ch).or_insert(0);
    *counter += 1;
}

assert_eq!(letters[&'s'], 2);
assert_eq!(letters[&'t'], 3);
assert_eq!(letters[&'u'], 1);
assert_eq!(letters.get(&'y'), None);

pub fn get<Q>(&self, k: &Q) -> Option<&V> where
    K: Borrow<Q>,
    Q: Hash + Eq + ?Sized, 

Returns a reference to the value corresponding to the key.

The key may be any borrowed form of the map's key type, but Hash and Eq on the borrowed form must match those for the key type.

Examples

use std::collections::HashMap;

let mut map = HashMap::new();
map.insert(1, "a");
assert_eq!(map.get(&1), Some(&"a"));
assert_eq!(map.get(&2), None);

pub fn get_key_value<Q>(&self, k: &Q) -> Option<(&K, &V)> where
    K: Borrow<Q>,
    Q: Hash + Eq + ?Sized, 

🔬 This is a nightly-only experimental API. (map_get_key_value)

Returns the key-value pair corresponding to the supplied key.

The supplied key may be any borrowed form of the map's key type, but Hash and Eq on the borrowed form must match those for the key type.

Examples

#![feature(map_get_key_value)]
use std::collections::HashMap;

let mut map = HashMap::new();
map.insert(1, "a");
assert_eq!(map.get_key_value(&1), Some((&1, &"a")));
assert_eq!(map.get_key_value(&2), None);

pub fn contains_key<Q>(&self, k: &Q) -> bool where
    K: Borrow<Q>,
    Q: Hash + Eq + ?Sized, 

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

The key may be any borrowed form of the map's key type, but Hash and Eq on the borrowed form must match those for the key type.

Examples

use std::collections::HashMap;

let mut map = HashMap::new();
map.insert(1, "a");
assert_eq!(map.contains_key(&1), true);
assert_eq!(map.contains_key(&2), false);

pub fn get_mut<Q>(&mut self, k: &Q) -> Option<&mut V> where
    K: Borrow<Q>,
    Q: Hash + Eq + ?Sized, 

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

The key may be any borrowed form of the map's key type, but Hash and Eq on the borrowed form must match those for the key type.

Examples

use std::collections::HashMap;

let mut map = HashMap::new();
map.insert(1, "a");
if let Some(x) = map.get_mut(&1) {
    *x = "b";
}
assert_eq!(map[&1], "b");

pub fn insert(&mut self, k: K, v: V) -> Option<V>

Inserts a key-value pair into the map.

If the map did not have this key present, None is returned.

If the map did have this key present, the value is updated, and the old value is returned. The key is not updated, though; this matters for types that can be == without being identical. See the module-level documentation for more.

Examples

use std::collections::HashMap;

let mut map = HashMap::new();
assert_eq!(map.insert(37, "a"), None);
assert_eq!(map.is_empty(), false);

map.insert(37, "b");
assert_eq!(map.insert(37, "c"), Some("b"));
assert_eq!(map[&37], "c");

pub fn remove<Q>(&mut self, k: &Q) -> Option<V> where
    K: Borrow<Q>,
    Q: Hash + Eq + ?Sized, 

Removes a key from the map, returning the value at the key if the key was previously in the map.

The key may be any borrowed form of the map's key type, but Hash and Eq on the borrowed form must match those for the key type.

Examples

use std::collections::HashMap;

let mut map = HashMap::new();
map.insert(1, "a");
assert_eq!(map.remove(&1), Some("a"));
assert_eq!(map.remove(&1), None);

pub fn remove_entry<Q>(&mut self, k: &Q) -> Option<(K, V)> where
    K: Borrow<Q>,
    Q: Hash + Eq + ?Sized, 

Removes a key from the map, returning the stored key and value if the key was previously in the map.

The key may be any borrowed form of the map's key type, but Hash and Eq on the borrowed form must match those for the key type.

Examples

use std::collections::HashMap;

let mut map = HashMap::new();
map.insert(1, "a");
assert_eq!(map.remove_entry(&1), Some((1, "a")));
assert_eq!(map.remove(&1), None);

pub fn retain<F>(&mut self, f: F) where
    F: FnMut(&K, &mut V) -> bool, 

Retains only the elements specified by the predicate.

In other words, remove all pairs (k, v) such that f(&k,&mut v) returns false.

Examples

use std::collections::HashMap;

let mut map: HashMap<i32, i32> = (0..8).map(|x|(x, x*10)).collect();
map.retain(|&k, _| k % 2 == 0);
assert_eq!(map.len(), 4);

pub fn raw_entry_mut(&mut self) -> RawEntryBuilderMut<K, V, S>

🔬 This is a nightly-only experimental API. (hash_raw_entry)

Creates a raw entry builder for the HashMap.

Raw entries provide the lowest level of control for searching and manipulating a map. They must be manually initialized with a hash and then manually searched. After this, insertions into a vacant entry still require an owned key to be provided.

Raw entries are useful for such exotic situations as:

• Hash memoization
• Deferring the creation of an owned key until it is known to be required
• Using a search key that doesn't work with the Borrow trait
• Using custom comparison logic without newtype wrappers

Because raw entries provide much more low-level control, it's much easier to put the HashMap into an inconsistent state which, while memory-safe, will cause the map to produce seemingly random results. Higher-level and more foolproof APIs like entry should be preferred when possible.

In particular, the hash used to initialized the raw entry must still be consistent with the hash of the key that is ultimately stored in the entry. This is because implementations of HashMap may need to recompute hashes when resizing, at which point only the keys are available.

Raw entries give mutable access to the keys. This must not be used to modify how the key would compare or hash, as the map will not re-evaluate where the key should go, meaning the keys may become "lost" if their location does not reflect their state. For instance, if you change a key so that the map now contains keys which compare equal, search may start acting erratically, with two keys randomly masking each other. Implementations are free to assume this doesn't happen (within the limits of memory-safety).

pub fn raw_entry(&self) -> RawEntryBuilder<K, V, S>

🔬 This is a nightly-only experimental API. (hash_raw_entry)

Creates a raw immutable entry builder for the HashMap.

Raw entries provide the lowest level of control for searching and manipulating a map. They must be manually initialized with a hash and then manually searched.

This is useful for

• Hash memoization
• Using a search key that doesn't work with the Borrow trait
• Using custom comparison logic without newtype wrappers

Unless you are in such a situation, higher-level and more foolproof APIs like get should be preferred.

Immutable raw entries have very limited use; you might instead want raw_entry_mut.

Trait Implementations

impl<'a, K, V, S> Extend<(&'a K, &'a V)> for NumMap<K, V, S> where
    K: 'a + Hash + Eq + Copy,
    V: 'a + Number,
    S: Default + BuildHasher, 

fn extend<Iter>(&mut self, iter: Iter) where
    Iter: IntoIterator<Item = (&'a K, &'a V)>, 

Extends a collection with the contents of an iterator.

impl<K, V, S> Extend<(K, V)> for NumMap<K, V, S> where
    K: Hash + Eq,
    V: Number,
    S: Default + BuildHasher, 

fn extend<Iter>(&mut self, iter: Iter) where
    Iter: IntoIterator<Item = (K, V)>, 

Extends a collection with the contents of an iterator.

impl<K, V, S> PartialOrd<HashMap<K, <V as Number>::NonZero, S>> for NumMap<K, V, S> where
    K: Eq + Hash,
    V: Number,
    S: BuildHasher,
    Self: PartialEq<HashMap<K, V::NonZero, S>>, 

Compares the two sets; sets are only considered Greater or Less if ALL of the mapping are Greater or Less (Equal is ignored).

fn partial_cmp(&self, rhs: &HashMap<K, V::NonZero, S>) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

#[must_use]

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use]

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use]

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use]

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<K, V, S> PartialOrd<NumMap<K, V, S>> for NumMap<K, V, S> where
    K: Eq + Hash,
    V: Number,
    S: BuildHasher,
    Self: PartialOrd<HashMap<K, V::NonZero, S>>, 

fn partial_cmp(&self, rhs: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

#[must_use]

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use]

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use]

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use]

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<K, V, S> AsMut<HashMap<K, <V as Number>::NonZero, S>> for NumMap<K, V, S> where
    V: Number, 

fn as_mut(&mut self) -> &mut HashMap<K, V::NonZero, S>

Performs the conversion.

impl<K, V, S> PartialEq<HashMap<K, <V as Number>::NonZero, S>> for NumMap<K, V, S> where
    V: Number,
    HashMap<K, V::NonZero, S>: PartialEq, 

fn eq(&self, rhs: &HashMap<K, V::NonZero, S>) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<K, V, S> PartialEq<NumMap<K, V, S>> for NumMap<K, V, S> where
    V: Number,
    Self: PartialEq<HashMap<K, V::NonZero, S>>, 

fn eq(&self, rhs: &Self) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<K, V, S> AsRef<HashMap<K, <V as Number>::NonZero, S>> for NumMap<K, V, S> where
    V: Number, 

fn as_ref(&self) -> &HashMap<K, V::NonZero, S>

Performs the conversion.

impl<K, V, S> IntoIterator for NumMap<K, V, S> where
    V: Number, 

type Item = (K, V)

The type of the elements being iterated over.

type IntoIter = IntoIter<K, V>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<K, V, S> Default for NumMap<K, V, S> where
    V: Number,
    HashMap<K, V::NonZero, S>: Default, 

fn default() -> Self

Returns the "default value" for a type.

impl<K, V, S> From<HashMap<K, <V as Number>::NonZero, S>> for NumMap<K, V, S> where
    V: Number, 

fn from(from: HashMap<K, V::NonZero, S>) -> Self

Performs the conversion.

impl<K, V, S> Clone for NumMap<K, V, S> where
    V: Number,
    HashMap<K, V::NonZero, S>: Clone, 

fn clone(&self) -> Self

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<K, V, S> Eq for NumMap<K, V, S> where
    V: Number,
    HashMap<K, V::NonZero, S>: Eq, 

impl<K, V, S> DerefMut for NumMap<K, V, S> where
    V: Number, 

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<K, V, S> Debug for NumMap<K, V, S> where
    V: Number,
    HashMap<K, V::NonZero, S>: Debug, 

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

Formats the value using the given formatter.

impl<K, V, S> Deref for NumMap<K, V, S> where
    V: Number, 

type Target = HashMap<K, V::NonZero, S>

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<K, V, S, A> FromIterator<A> for NumMap<K, V, S> where
    K: Hash + Eq,
    V: Number,
    S: Default + BuildHasher,
    A: Into<(K, V)>, 

fn from_iter<Iter>(iter: Iter) -> Self where
    Iter: IntoIterator<Item = A>, 

Creates a value from an iterator.

impl<K, V, S> Borrow<HashMap<K, <V as Number>::NonZero, S>> for NumMap<K, V, S> where
    V: Number, 

fn borrow(&self) -> &HashMap<K, V::NonZero, S>

Immutably borrows from an owned value.

impl<K, V, S> BorrowMut<HashMap<K, <V as Number>::NonZero, S>> for NumMap<K, V, S> where
    V: Number, 

fn borrow_mut(&mut self) -> &mut HashMap<K, V::NonZero, S>

Mutably borrows from an owned value.