Struct heapless::IndexMap[−][src]

pub struct IndexMap<K, V, N, S> where
    K: Eq + Hash,
    N: ArrayLength<Bucket<K, V>> + ArrayLength<Option<Pos>>,  { /* fields omitted */ }
Expand description

Fixed capacity IndexMap

Note that you cannot use IndexMap directly, since it is generic around the hashing algorithm in use. Pick a concrete instantiation like FnvIndexMap instead or create your own.

Note that the capacity of the IndexMap must be a power of 2.

Examples

Since IndexMap cannot be used directly, we’re using its FnvIndexMap instantiation for this example.

use heapless::FnvIndexMap;
use heapless::consts::*;

// A hash map with a capacity of 16 key-value pairs allocated on the stack
let mut book_reviews = FnvIndexMap::<_, _, U16>::new();

// review some books.
book_reviews.insert("Adventures of Huckleberry Finn",    "My favorite book.").unwrap();
book_reviews.insert("Grimms' Fairy Tales",               "Masterpiece.").unwrap();
book_reviews.insert("Pride and Prejudice",               "Very enjoyable.").unwrap();
book_reviews.insert("The Adventures of Sherlock Holmes", "Eye lyked it alot.").unwrap();

// check for a specific one.
if !book_reviews.contains_key("Les Misérables") {
    println!("We've got {} reviews, but Les Misérables ain't one.",
             book_reviews.len());
}

// oops, this review has a lot of spelling mistakes, let's delete it.
book_reviews.remove("The Adventures of Sherlock Holmes");

// look up the values associated with some keys.
let to_find = ["Pride and Prejudice", "Alice's Adventure in Wonderland"];
for book in &to_find {
    match book_reviews.get(book) {
        Some(review) => println!("{}: {}", book, review),
        None => println!("{} is unreviewed.", book)
    }
}

// iterate over everything.
for (book, review) in &book_reviews {
    println!("{}: \"{}\"", book, review);
}

Implementations

Creates an empty IndexMap.

NOTE This constructor will become a const fn in the future

Returns the number of elements the map can hold

Return an iterator over the keys of the map, in their order

use heapless::FnvIndexMap;
use heapless::consts::*;

let mut map = FnvIndexMap::<_, _, U16>::new();
map.insert("a", 1).unwrap();
map.insert("b", 2).unwrap();
map.insert("c", 3).unwrap();

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

Return an iterator over the values of the map, in their order

use heapless::FnvIndexMap;
use heapless::consts::*;

let mut map = FnvIndexMap::<_, _, U16>::new();
map.insert("a", 1).unwrap();
map.insert("b", 2).unwrap();
map.insert("c", 3).unwrap();

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

Return an iterator over mutable references to the the values of the map, in their order

use heapless::FnvIndexMap;
use heapless::consts::*;

let mut map = FnvIndexMap::<_, _, U16>::new();
map.insert("a", 1).unwrap();
map.insert("b", 2).unwrap();
map.insert("c", 3).unwrap();

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

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

Return an iterator over the key-value pairs of the map, in their order

use heapless::FnvIndexMap;
use heapless::consts::*;

let mut map = FnvIndexMap::<_, _, U16>::new();
map.insert("a", 1).unwrap();
map.insert("b", 2).unwrap();
map.insert("c", 3).unwrap();

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

Return an iterator over the key-value pairs of the map, in their order

use heapless::FnvIndexMap;
use heapless::consts::*;

let mut map = FnvIndexMap::<_, _, U16>::new();
map.insert("a", 1).unwrap();
map.insert("b", 2).unwrap();
map.insert("c", 3).unwrap();

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

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

Return the number of key-value pairs in the map.

Computes in O(1) time.

use heapless::FnvIndexMap;
use heapless::consts::*;

let mut a = FnvIndexMap::<_, _, U16>::new();
assert_eq!(a.len(), 0);
a.insert(1, "a").unwrap();
assert_eq!(a.len(), 1);

Returns true if the map contains no elements.

Computes in O(1) time.

use heapless::FnvIndexMap;
use heapless::consts::*;

let mut a = FnvIndexMap::<_, _, U16>::new();
assert!(a.is_empty());
a.insert(1, "a");
assert!(!a.is_empty());

Remove all key-value pairs in the map, while preserving its capacity.

Computes in O(n) time.

use heapless::FnvIndexMap;
use heapless::consts::*;

let mut a = FnvIndexMap::<_, _, U16>::new();
a.insert(1, "a");
a.clear();
assert!(a.is_empty());

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.

Computes in O(1) time (average).

use heapless::FnvIndexMap;
use heapless::consts::*;

let mut map = FnvIndexMap::<_, _, U16>::new();
map.insert(1, "a").unwrap();
assert_eq!(map.get(&1), Some(&"a"));
assert_eq!(map.get(&2), None);

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.

Computes in O(1) time (average).

Examples

use heapless::FnvIndexMap;
use heapless::consts::*;

let mut map = FnvIndexMap::<_, _, U8>::new();
map.insert(1, "a").unwrap();
assert_eq!(map.contains_key(&1), true);
assert_eq!(map.contains_key(&2), false);

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.

Computes in O(1) time (average).

Examples

use heapless::FnvIndexMap;
use heapless::consts::*;

let mut map = FnvIndexMap::<_, _, U8>::new();
map.insert(1, "a").unwrap();
if let Some(x) = map.get_mut(&1) {
    *x = "b";
}
assert_eq!(map[&1], "b");

Inserts a key-value pair into the map.

If an equivalent key already exists in the map: the key remains and retains in its place in the order, its corresponding value is updated with value and the older value is returned inside Some(_).

If no equivalent key existed in the map: the new key-value pair is inserted, last in order, and None is returned.

Computes in O(1) time (average).

See also entry if you you want to insert or modify or if you need to get the index of the corresponding key-value pair.

Examples

use heapless::FnvIndexMap;
use heapless::consts::*;

let mut map = FnvIndexMap::<_, _, U8>::new();
assert_eq!(map.insert(37, "a"), Ok(None));
assert_eq!(map.is_empty(), false);

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

Same as swap_remove

Computes in O(1) time (average).

Examples

use heapless::FnvIndexMap;
use heapless::consts::*;

let mut map = FnvIndexMap::<_, _, U8>::new();
map.insert(1, "a").unwrap();
assert_eq!(map.remove(&1), Some("a"));
assert_eq!(map.remove(&1), None);

Remove the key-value pair equivalent to key and return its value.

Like Vec::swap_remove, the pair is removed by swapping it with the last element of the map and popping it off. This perturbs the postion of what used to be the last element!

Return None if key is not in map.

Computes in O(1) time (average).

Trait Implementations

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

Formats the value using the given formatter. Read more

Returns the “default value” for a type. Read more

Extends a collection with the contents of an iterator. Read more

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

Extends a collection with exactly one element.

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

Reserves capacity in a collection for the given number of additional elements. Read more

Extends a collection with the contents of an iterator. Read more

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

Extends a collection with exactly one element.

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

Reserves capacity in a collection for the given number of additional elements. Read more

Creates a value from an iterator. Read more

The returned type after indexing.

Performs the indexing (container[index]) operation. Read more

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

The type of the elements being iterated over.

Which kind of iterator are we turning this into?

Creates an iterator from a value. Read more

The type of the elements being iterated over.

Which kind of iterator are we turning this into?

Creates an iterator from a value. Read more

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

This method tests for !=.

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Performs the conversion.

Performs the conversion.

Should always be Self

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.