Struct EnumMap

pub struct EnumMap<K: Enum<V>, V> { /* private fields */ }

An enum mapping.

This internally uses an array which stores a value for each possible enum value. To work, it requires implementation of internal (private, although public due to macro limitations) trait which allows extracting information about an enum, which can be automatically generated using #[derive(Enum)] macro.

Additionally, bool and u8 automatically derives from Enum. While u8 is not technically an enum, it’s convenient to consider it like one. In particular, reverse-complement in benchmark game could be using u8 as an enum.

Examples

use enum_map::{enum_map, Enum, EnumMap};

#[derive(Enum)]
enum Example {
    A,
    B,
    C,
}

fn main() {
    let mut map = EnumMap::new();
    // new initializes map with default values
    assert_eq!(map[Example::A], 0);
    map[Example::A] = 3;
    assert_eq!(map[Example::A], 3);
}

Implementations

impl<K: Enum<V>, V> EnumMap<K, V>

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

An iterator visiting all values. The iterator type is &V.

Examples

use enum_map::enum_map;

fn main() {
    let map = enum_map! { false => 3, true => 4 };
    let mut values = map.values();
    assert_eq!(values.next(), Some(&3));
    assert_eq!(values.next(), Some(&4));
    assert_eq!(values.next(), None);
}

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

An iterator visiting all values mutably. The iterator type is &mut V.

Examples

use enum_map::enum_map;

fn main() {
    let mut map = enum_map! { _ => 2 };
    for value in map.values_mut() {
        *value += 2;
    }
    assert_eq!(map[false], 4);
    assert_eq!(map[true], 4);
}

impl<K: Enum<V>, V: Default> EnumMap<K, V>

pub fn new() -> Self

Creates an enum map with default values.

Examples

use enum_map::{Enum, EnumMap};

#[derive(Enum)]
enum Example {
    A,
}

fn main() {
    let enum_map = EnumMap::<_, i32>::new();
    assert_eq!(enum_map[Example::A], 0);
}

impl<K: Enum<V>, V> EnumMap<K, V>

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

Returns an iterator over enum map.

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

Returns a mutable iterator over enum map.

pub fn len(&self) -> usize

Returns number of elements in enum map.

pub fn is_empty(&self) -> bool

Returns whether the enum variant set is empty.

This isn’t particularly useful, as there is no real reason to use enum map for enums without variants. However, it is provided for consistency with data structures providing len method (and I will admit, to avoid clippy warnings).

Examples

use enum_map::{Enum, EnumMap};

#[derive(Enum)]
enum Void {}

#[derive(Enum)]
enum SingleVariant {
    Variant,
}

fn main() {
    assert!(EnumMap::<Void, ()>::new().is_empty());
    assert!(!EnumMap::<SingleVariant, ()>::new().is_empty());
}

pub fn swap(&mut self, a: K, b: K)

Swaps two indexes.

Examples

use enum_map::enum_map;

fn main() {
    let mut map = enum_map! { false => 0, true => 1 };
    map.swap(false, true);
    assert_eq!(map[false], 1);
    assert_eq!(map[true], 0);
}

pub fn as_slice(&self) -> &[V]

Converts an enum map to a slice representing values.

pub fn as_mut_slice(&mut self) -> &mut [V]

Converts a mutable enum map to a mutable slice representing values.

pub fn as_ptr(&self) -> *const V

Returns a raw pointer to the enum map’s slice.

The caller must ensure that the slice outlives the pointer this function returns, or else it will end up pointing to garbage.

Examples

use enum_map::{enum_map, EnumMap};

fn main() {
    let map = enum_map! { 5 => 42, _ => 0 };
    assert_eq!(unsafe { *map.as_ptr().offset(5) }, 42);
}

pub fn as_mut_ptr(&mut self) -> *mut V

Returns an unsafe mutable pointer to the enum map’s slice.

The caller must ensure that the slice outlives the pointer this function returns, or else it will end up pointing to garbage.

Examples

use enum_map::{enum_map, EnumMap};

fn main() {
    let mut map = enum_map! { _ => 0 };
    unsafe {
        *map.as_mut_ptr().offset(11) = 23
    };
    assert_eq!(map[11], 23);
}

Trait Implementations

impl<K: Enum<V>, V> Clone for EnumMap<K, V>

where K::Array: 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: Enum<V> + Debug, V: Debug> Debug for EnumMap<K, V>

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

Formats the value using the given formatter.

impl<K: Enum<V>, V: Default> Default for EnumMap<K, V>

fn default() -> Self

Returns the “default value” for a type.

impl<'a, K, V> Extend<(&'a K, &'a V)> for EnumMap<K, V>

where K: Enum<V> + Copy, V: Copy,

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

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

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

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

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

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

impl<K: Enum<V>, V> Extend<(K, V)> for EnumMap<K, V>

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

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

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

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

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

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

impl<F: FnMut(K) -> V, K: Enum<V>, V> From<F> for EnumMap<K, V>

fn from(f: F) -> Self

Converts to this type from the input type.

impl<K: Enum<V>, V: Hash> Hash for EnumMap<K, V>

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, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<K: Enum<V>, V> Index<K> for EnumMap<K, V>

type Output = V

The returned type after indexing.

fn index(&self, key: K) -> &V

Performs the indexing (container[index]) operation.

impl<K: Enum<V>, V> IndexMut<K> for EnumMap<K, V>

fn index_mut(&mut self, key: K) -> &mut V

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

impl<'a, K: Enum<V>, V> IntoIterator for &'a EnumMap<K, V>

type Item = (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

Creates an iterator from a value.

impl<'a, K: Enum<V>, V> IntoIterator for &'a mut EnumMap<K, V>

type Item = (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

Creates an iterator from a value.

impl<K: Enum<V>, V> IntoIterator for EnumMap<K, V>

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: Enum<V>, V: PartialEq> PartialEq for EnumMap<K, V>

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<K: Enum<V>, V> Copy for EnumMap<K, V>

where K::Array: Copy,

impl<K: Enum<V>, V: Eq> Eq for EnumMap<K, V>