Struct trie::map::Map

pub struct Map<T> { /* fields omitted */ }

A map implemented as a radix trie.

Keys are split into sequences of 4 bits, which are used to place elements in 16-entry arrays which are nested to form a tree structure. Inserted elements are placed as close to the top of the tree as possible. The most significant bits of the key are used to assign the key to a node/bucket in the first layer. If there are no other elements keyed by the same 4 bits in the first layer, a leaf node will be created in the first layer. When keys coincide, the next 4 bits are used to assign the node to a bucket in the next layer, with this process continuing until an empty spot is found or there are no more bits left in the key. As a result, the maximum depth using 32-bit usize keys is 8. The worst collisions occur for very small numbers. For example, 1 and 2 are identical in all but their least significant 4 bits. If both numbers are used as keys, a chain of maximum length will be created to differentiate them.

Examples

let mut map = trie::Map::new();
map.insert(27, "Olaf");
map.insert(1, "Edgar");
map.insert(13, "Ruth");
map.insert(1, "Martin");

assert_eq!(map.len(), 3);
assert_eq!(map.get(&1), Some(&"Martin"));

if !map.contains_key(&90) {
    println!("Nobody is keyed 90");
}

// Update a key
match map.get_mut(&1) {
    Some(value) => *value = "Olga",
    None => (),
}

map.remove(&13);
assert_eq!(map.len(), 2);

// Print the key value pairs, ordered by key.
for (key, value) in map.iter() {
    // Prints `1: Olga` then `27: Olaf`
    println!("{}: {}", key, value);
}

map.clear();
assert!(map.is_empty());

Methods

impl<T> Map<T>

fn new() -> Map<T>

Creates an empty map.

Examples

let mut map: trie::Map<&str> = trie::Map::new();

fn each_reverse<'a, F>(&'a self, f: F) -> bool where
    F: FnMut(&usize, &'a T) -> bool, 

Visits all key-value pairs in reverse order. Aborts traversal when f returns false. Returns true if f returns true for all elements.

Examples

let map: trie::Map<&str> = [(1, "a"), (2, "b"), (3, "c")].iter().cloned().collect();

let mut vec = vec![];
assert_eq!(true, map.each_reverse(|&key, &value| { vec.push((key, value)); true }));
assert_eq!(vec, [(3, "c"), (2, "b"), (1, "a")]);

// Stop when we reach 2
let mut vec = vec![];
assert_eq!(false, map.each_reverse(|&key, &value| { vec.push(value); key != 2 }));
assert_eq!(vec, ["c", "b"]);

fn keys(&self) -> Keys<T>

Gets an iterator visiting all keys in ascending order by the keys. The iterator's element type is usize.

fn values(&self) -> Values<T>

Gets an iterator visiting all values in ascending order by the keys. The iterator's element type is &'r T.

fn iter(&self) -> Iter<T>

Gets an iterator over the key-value pairs in the map, ordered by keys.

Examples

let map: trie::Map<&str> = [(3, "c"), (1, "a"), (2, "b")].iter().cloned().collect();

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

fn iter_mut(&mut self) -> IterMut<T>

Gets an iterator over the key-value pairs in the map, with the ability to mutate the values.

Examples

let mut map: trie::Map<i32> = [(1, 2), (2, 4), (3, 6)].iter().cloned().collect();

for (key, value) in map.iter_mut() {
    *value = -(key as i32);
}

assert_eq!(map.get(&1), Some(&-1));
assert_eq!(map.get(&2), Some(&-2));
assert_eq!(map.get(&3), Some(&-3));

fn len(&self) -> usize

Return the number of elements in the map.

Examples

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

fn is_empty(&self) -> bool

Return true if the map contains no elements.

Examples

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

fn clear(&mut self)

Clears the map, removing all values.

Examples

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

fn get(&self, key: &usize) -> Option<&T>

Returns a reference to the value corresponding to the key.

Examples

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

fn contains_key(&self, key: &usize) -> bool

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

Examples

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

fn get_mut(&mut self, key: &usize) -> Option<&mut T>

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

Examples

let mut map = trie::Map::new();
map.insert(1, "a");
match map.get_mut(&1) {
    Some(x) => *x = "b",
    None => (),
}
assert_eq!(map[&1], "b");

fn insert(&mut self, key: usize, value: T) -> Option<T>

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

Examples

let mut map = trie::Map::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");

fn remove(&mut self, key: &usize) -> Option<T>

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

Examples

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

impl<T> Map<T>

fn lower_bound(&self, key: usize) -> Range<T>

Gets an iterator pointing to the first key-value pair whose key is not less than key. If all keys in the map are less than key an empty iterator is returned.

Examples

let map: trie::Map<&str> = [(2, "a"), (4, "b"), (6, "c")].iter().cloned().collect();

assert_eq!(map.lower_bound(4).next(), Some((4, &"b")));
assert_eq!(map.lower_bound(5).next(), Some((6, &"c")));
assert_eq!(map.lower_bound(10).next(), None);

fn upper_bound(&self, key: usize) -> Range<T>

Gets an iterator pointing to the first key-value pair whose key is greater than key. If all keys in the map are not greater than key an empty iterator is returned.

Examples

let map: trie::Map<&str> = [(2, "a"), (4, "b"), (6, "c")].iter().cloned().collect();

assert_eq!(map.upper_bound(4).next(), Some((6, &"c")));
assert_eq!(map.upper_bound(5).next(), Some((6, &"c")));
assert_eq!(map.upper_bound(10).next(), None);

fn lower_bound_mut(&mut self, key: usize) -> RangeMut<T>

Gets an iterator pointing to the first key-value pair whose key is not less than key. If all keys in the map are less than key an empty iterator is returned.

Examples

let mut map: trie::Map<&str> = [(2, "a"), (4, "b"), (6, "c")].iter().cloned().collect();

assert_eq!(map.lower_bound_mut(4).next(), Some((4, &mut "b")));
assert_eq!(map.lower_bound_mut(5).next(), Some((6, &mut "c")));
assert_eq!(map.lower_bound_mut(10).next(), None);

for (key, value) in map.lower_bound_mut(4) {
    *value = "changed";
}

assert_eq!(map.get(&2), Some(&"a"));
assert_eq!(map.get(&4), Some(&"changed"));
assert_eq!(map.get(&6), Some(&"changed"));

fn upper_bound_mut(&mut self, key: usize) -> RangeMut<T>

Gets an iterator pointing to the first key-value pair whose key is greater than key. If all keys in the map are not greater than key an empty iterator is returned.

Examples

let mut map: trie::Map<&str> = [(2, "a"), (4, "b"), (6, "c")].iter().cloned().collect();

assert_eq!(map.upper_bound_mut(4).next(), Some((6, &mut "c")));
assert_eq!(map.upper_bound_mut(5).next(), Some((6, &mut "c")));
assert_eq!(map.upper_bound_mut(10).next(), None);

for (key, value) in map.upper_bound_mut(4) {
    *value = "changed";
}

assert_eq!(map.get(&2), Some(&"a"));
assert_eq!(map.get(&4), Some(&"b"));
assert_eq!(map.get(&6), Some(&"changed"));

impl<T> Map<T>

fn entry(&mut self, key: usize) -> Entry<T>

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

Trait Implementations

impl<T: Clone> Clone for Map<T>

fn clone(&self) -> Map<T>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T: PartialEq> PartialEq for Map<T>

fn eq(&self, other: &Map<T>) -> bool

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

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

This method tests for !=.

impl<T: Eq> Eq for Map<T>

impl<T: PartialOrd> PartialOrd for Map<T>

fn partial_cmp(&self, other: &Map<T>) -> Option<Ordering>

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

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

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

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

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

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

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

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<T: Ord> Ord for Map<T>

fn cmp(&self, other: &Map<T>) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

impl<T: Debug> Debug for Map<T>

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

Formats the value using the given formatter.

impl<T> Default for Map<T>

fn default() -> Map<T>

Returns the "default value" for a type.

impl<T> FromIterator<(usize, T)> for Map<T>

fn from_iter<I: IntoIterator<Item = (usize, T)>>(iter: I) -> Map<T>

Creates a value from an iterator.

impl<T> Extend<(usize, T)> for Map<T>

fn extend<I: IntoIterator<Item = (usize, T)>>(&mut self, iter: I)

Extends a collection with the contents of an iterator.

impl<T: Hash> Hash for Map<T>

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given [Hasher].

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given [Hasher].

impl<'a, T> Index<&'a usize> for Map<T>

type Output = T

The returned type after indexing.

fn index(&self, i: &'a usize) -> &T

Performs the indexing (container[index]) operation.

impl<'a, T> IndexMut<&'a usize> for Map<T>

fn index_mut(&mut self, i: &'a usize) -> &mut T

Performs the mutable indexing (container[index]) operation.

impl<'a, T> IntoIterator for &'a Map<T>

type Item = (usize, &'a T)

The type of the elements being iterated over.

type IntoIter = Iter<'a, T>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Iter<'a, T>

Creates an iterator from a value.

impl<'a, T> IntoIterator for &'a mut Map<T>

type Item = (usize, &'a mut T)

The type of the elements being iterated over.

type IntoIter = IterMut<'a, T>

Which kind of iterator are we turning this into?

fn into_iter(self) -> IterMut<'a, T>

Creates an iterator from a value.