# [−] [src] Struct heapless::IndexMap

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

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

### `impl<K, V, N, S> IndexMap<K, V, N, BuildHasherDefault<S>> where
K: Eq + Hash,
S: Default + Hasher,
N: ArrayLength<Bucket<K, V>> + ArrayLength<Option<Pos>> + PowerOfTwo,` [src]

#### `pub fn new() -> Self` [src]

Creates an empty `IndexMap`.

NOTE This constructor will become a `const fn` in the future

### `impl<K, V, N, S> IndexMap<K, V, N, S> where
K: Eq + Hash,
S: BuildHasher,
N: ArrayLength<Bucket<K, V>> + ArrayLength<Option<Pos>>,` [src]

#### `pub fn capacity(&self) -> usize` [src]

Returns the number of elements the map can hold

#### `pub fn keys(&self) -> impl Iterator<Item = &K>` [src]

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);
    }

#### `pub fn values(&self) -> impl Iterator<Item = &V>` [src]

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);
    }

#### `pub fn values_mut(&mut self) -> impl Iterator<Item = &mut V>` [src]

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);
    }

#### `pub fn iter(&self) -> Iter<'_, K, V>` [src]

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);
    }

#### `pub fn iter_mut(&mut self) -> IterMut<'_, K, V>` [src]

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);
    }

#### `pub fn len(&self) -> usize` [src]

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);

#### `pub fn is_empty(&self) -> bool` [src]

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());

#### `pub fn clear(&mut self)` [src]

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());

#### `pub fn get<Q: ?Sized>(&self, key: &Q) -> Option<&V> where
K: Borrow<Q>,
Q: Hash + Eq,` [src]

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);

#### `pub fn contains_key<Q: ?Sized>(&self, key: &Q) -> bool where
K: Borrow<Q>,
Q: Eq + Hash,` [src]

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);

#### `pub fn get_mut<'v, Q: ?Sized>(&'v mut self, key: &Q) -> Option<&'v mut V> where
K: Borrow<Q>,
Q: Hash + Eq,` [src]

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");

#### `pub fn insert(&mut self, key: K, value: V) -> Result<Option<V>, (K, V)>` [src]

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");

#### `pub fn remove<Q: ?Sized>(&mut self, key: &Q) -> Option<V> where
K: Borrow<Q>,
Q: Hash + Eq,` [src]

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);

#### `pub fn swap_remove<Q: ?Sized>(&mut self, key: &Q) -> Option<V> where
K: Borrow<Q>,
Q: Hash + Eq,` [src]

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

### `impl<K, V, N, S> Clone for IndexMap<K, V, N, S> where
K: Eq + Hash + Clone,
V: Clone,
S: Clone,
N: ArrayLength<Bucket<K, V>> + ArrayLength<Option<Pos>>,` [src]

#### `fn clone(&self) -> Self` [src]

Returns a copy of the value. Read more

#### `pub fn clone_from(&mut self, source: &Self)`1.0.0 [src]

Performs copy-assignment from `source`. Read more

### `impl<K, V, N, S> Debug for IndexMap<K, V, N, S> where
K: Eq + Hash + Debug,
V: Debug,
S: BuildHasher,
N: ArrayLength<Bucket<K, V>> + ArrayLength<Option<Pos>>,` [src]

#### `fn fmt(&self, f: &mut Formatter<'_>) -> Result` [src]

Formats the value using the given formatter. Read more

### `impl<K, V, N, S> Default for IndexMap<K, V, N, S> where
K: Eq + Hash,
S: BuildHasher + Default,
N: ArrayLength<Bucket<K, V>> + ArrayLength<Option<Pos>>,` [src]

#### `fn default() -> Self` [src]

Returns the "default value" for a type. Read more

### `impl<K, V, N, S> Eq for IndexMap<K, V, N, S> where
K: Eq + Hash,
V: Eq,
S: BuildHasher,
N: ArrayLength<Bucket<K, V>> + ArrayLength<Option<Pos>>,` [src]

### `impl<'a, K, V, N, S> Extend<(&'a K, &'a V)> for IndexMap<K, V, N, S> where
K: Eq + Hash + Copy,
V: Copy,
S: BuildHasher,
N: ArrayLength<Bucket<K, V>> + ArrayLength<Option<Pos>>,` [src]

#### `fn extend<I>(&mut self, iterable: I) where
I: IntoIterator<Item = (&'a K, &'a V)>,` [src]

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

#### `pub fn extend_one(&mut self, item: A)` [src]

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

Extends a collection with exactly one element.

#### `pub fn extend_reserve(&mut self, additional: usize)` [src]

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

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

### `impl<K, V, N, S> Extend<(K, V)> for IndexMap<K, V, N, S> where
K: Eq + Hash,
S: BuildHasher,
N: ArrayLength<Bucket<K, V>> + ArrayLength<Option<Pos>>,` [src]

#### `fn extend<I>(&mut self, iterable: I) where
I: IntoIterator<Item = (K, V)>,` [src]

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

#### `pub fn extend_one(&mut self, item: A)` [src]

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

Extends a collection with exactly one element.

#### `pub fn extend_reserve(&mut self, additional: usize)` [src]

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

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

### `impl<K, V, N, S> FromIterator<(K, V)> for IndexMap<K, V, N, S> where
K: Eq + Hash,
S: BuildHasher + Default,
N: ArrayLength<Bucket<K, V>> + ArrayLength<Option<Pos>>,` [src]

#### `fn from_iter<I>(iterable: I) -> Self where
I: IntoIterator<Item = (K, V)>,` [src]

Creates a value from an iterator. Read more

### `impl<'a, K, Q: ?Sized, V, N, S> Index<&'a Q> for IndexMap<K, V, N, S> where
K: Eq + Hash + Borrow<Q>,
Q: Eq + Hash,
S: BuildHasher,
N: ArrayLength<Bucket<K, V>> + ArrayLength<Option<Pos>>,` [src]

#### `type Output = V`

The returned type after indexing.

#### `fn index(&self, key: &Q) -> &V` [src]

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

### `impl<'a, K, Q: ?Sized, V, N, S> IndexMut<&'a Q> for IndexMap<K, V, N, S> where
K: Eq + Hash + Borrow<Q>,
Q: Eq + Hash,
S: BuildHasher,
N: ArrayLength<Bucket<K, V>> + ArrayLength<Option<Pos>>,` [src]

#### `fn index_mut(&mut self, key: &Q) -> &mut V` [src]

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

### `impl<'a, K, V, N, S> IntoIterator for &'a IndexMap<K, V, N, S> where
K: Eq + Hash,
S: BuildHasher,
N: ArrayLength<Bucket<K, V>> + ArrayLength<Option<Pos>>,` [src]

#### `type Item = (&'a K, &'a V)`

The type of the elements being iterated over.

#### `type IntoIter = Iter<'a, K, V>`

Which kind of iterator are we turning this into?

#### `fn into_iter(self) -> Self::IntoIter` [src]

Creates an iterator from a value. Read more

### `impl<'a, K, V, N, S> IntoIterator for &'a mut IndexMap<K, V, N, S> where
K: Eq + Hash,
S: BuildHasher,
N: ArrayLength<Bucket<K, V>> + ArrayLength<Option<Pos>>,` [src]

#### `type Item = (&'a K, &'a mut V)`

The type of the elements being iterated over.

#### `type IntoIter = IterMut<'a, K, V>`

Which kind of iterator are we turning this into?

#### `fn into_iter(self) -> Self::IntoIter` [src]

Creates an iterator from a value. Read more

### `impl<K, V, N, S, N2, S2> PartialEq<IndexMap<K, V, N2, S2>> for IndexMap<K, V, N, S> where
K: Eq + Hash,
V: Eq,
S: BuildHasher,
N: ArrayLength<Bucket<K, V>> + ArrayLength<Option<Pos>>,
S2: BuildHasher,
N2: ArrayLength<Bucket<K, V>> + ArrayLength<Option<Pos>>,` [src]

#### `fn eq(&self, other: &IndexMap<K, V, N2, S2>) -> bool` [src]

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

#### `#[must_use]pub fn ne(&self, other: &Rhs) -> bool` 1.0.0 [src]

This method tests for `!=`.

## Auto Trait Implementations

### `impl<K, V, N, S> Send for IndexMap<K, V, N, S> where
K: Send,
S: Send,
V: Send,` [src]

### `impl<K, V, N, S> Sync for IndexMap<K, V, N, S> where
K: Sync,
S: Sync,
V: Sync,` [src]

### `impl<K, V, N, S> Unpin for IndexMap<K, V, N, S> where
S: Unpin,
<N as ArrayLength<Bucket<K, V>>>::ArrayType: Unpin,
<N as ArrayLength<Option<Pos>>>::ArrayType: Unpin,` [src]

## Blanket Implementations

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `pub fn type_id(&self) -> TypeId` [src]

Gets the `TypeId` of `self`. Read more

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow(&self) -> &T` [src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow_mut(&mut self) -> &mut T` [src]

Mutably borrows from an owned value. Read more

### `impl<T> From<T> for T` [src]

#### `pub fn from(t: T) -> T` [src]

Performs the conversion.

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `pub fn into(self) -> U` [src]

Performs the conversion.

### `impl<T> Same<T> for T` [src]

#### `type Output = T`

Should always be `Self`

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

#### `pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>` [src]

Performs the conversion.

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

#### `type Error = <U as TryFrom<T>>::Error`

The type returned in the event of a conversion error.

#### `pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>` [src]

Performs the conversion.