Struct heapless::IndexSet

pub struct IndexSet<T, S, const N: usize> { /* private fields */ }

Fixed capacity IndexSet.

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

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

Examples

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

use heapless::FnvIndexSet;

// A hash set with a capacity of 16 elements allocated on the stack
let mut books = FnvIndexSet::<_, 16>::new();

// Add some books.
books.insert("A Dance With Dragons").unwrap();
books.insert("To Kill a Mockingbird").unwrap();
books.insert("The Odyssey").unwrap();
books.insert("The Great Gatsby").unwrap();

// Check for a specific one.
if !books.contains("The Winds of Winter") {
    println!("We have {} books, but The Winds of Winter ain't one.",
             books.len());
}

// Remove a book.
books.remove("The Odyssey");

// Iterate over everything.
for book in &books {
    println!("{}", book);
}

Implementations

impl<T, S, const N: usize> IndexSet<T, BuildHasherDefault<S>, N>

pub const fn new() -> Self

Creates an empty IndexSet

impl<T, S, const N: usize> IndexSet<T, S, N>

where T: Eq + Hash, S: BuildHasher,

pub fn capacity(&self) -> usize

Returns the number of elements the set can hold

Examples

use heapless::FnvIndexSet;

let set = FnvIndexSet::<i32, 16>::new();
assert_eq!(set.capacity(), 16);

pub fn iter(&self) -> Iter<'_, T>

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

Examples

use heapless::FnvIndexSet;

let mut set = FnvIndexSet::<_, 16>::new();
set.insert("a").unwrap();
set.insert("b").unwrap();

// Will print in an arbitrary order.
for x in set.iter() {
    println!("{}", x);
}

pub fn first(&self) -> Option<&T>

Get the first value

Computes in O(1) time

pub fn last(&self) -> Option<&T>

Get the last value

Computes in O(1) time

pub fn difference<'a, S2, const N2: usize>( &'a self, other: &'a IndexSet<T, S2, N2>, ) -> Difference<'a, T, S2, N2>

where S2: BuildHasher,

Visits the values representing the difference, i.e. the values that are in self but not in other.

Examples

use heapless::FnvIndexSet;

let mut a: FnvIndexSet<_, 16> = [1, 2, 3].iter().cloned().collect();
let mut b: FnvIndexSet<_, 16> = [4, 2, 3, 4].iter().cloned().collect();

// Can be seen as `a - b`.
for x in a.difference(&b) {
    println!("{}", x); // Print 1
}

let diff: FnvIndexSet<_, 16> = a.difference(&b).collect();
assert_eq!(diff, [1].iter().collect::<FnvIndexSet<_, 16>>());

// Note that difference is not symmetric,
// and `b - a` means something else:
let diff: FnvIndexSet<_, 16> = b.difference(&a).collect();
assert_eq!(diff, [4].iter().collect::<FnvIndexSet<_, 16>>());

pub fn symmetric_difference<'a, S2, const N2: usize>( &'a self, other: &'a IndexSet<T, S2, N2>, ) -> impl Iterator<Item = &'a T>

where S2: BuildHasher,

Visits the values representing the symmetric difference, i.e. the values that are in self or in other but not in both.

Examples

use heapless::FnvIndexSet;

let mut a: FnvIndexSet<_, 16> = [1, 2, 3].iter().cloned().collect();
let mut b: FnvIndexSet<_, 16> = [4, 2, 3, 4].iter().cloned().collect();

// Print 1, 4 in that order order.
for x in a.symmetric_difference(&b) {
    println!("{}", x);
}

let diff1: FnvIndexSet<_, 16> = a.symmetric_difference(&b).collect();
let diff2: FnvIndexSet<_, 16> = b.symmetric_difference(&a).collect();

assert_eq!(diff1, diff2);
assert_eq!(diff1, [1, 4].iter().collect::<FnvIndexSet<_, 16>>());

pub fn intersection<'a, S2, const N2: usize>( &'a self, other: &'a IndexSet<T, S2, N2>, ) -> Intersection<'a, T, S2, N2>

where S2: BuildHasher,

Visits the values representing the intersection, i.e. the values that are both in self and other.

Examples

use heapless::FnvIndexSet;

let mut a: FnvIndexSet<_, 16> = [1, 2, 3].iter().cloned().collect();
let mut b: FnvIndexSet<_, 16> = [4, 2, 3, 4].iter().cloned().collect();

// Print 2, 3 in that order.
for x in a.intersection(&b) {
    println!("{}", x);
}

let intersection: FnvIndexSet<_, 16> = a.intersection(&b).collect();
assert_eq!(intersection, [2, 3].iter().collect::<FnvIndexSet<_, 16>>());

pub fn union<'a, S2, const N2: usize>( &'a self, other: &'a IndexSet<T, S2, N2>, ) -> impl Iterator<Item = &'a T>

where S2: BuildHasher,

Visits the values representing the union, i.e. all the values in self or other, without duplicates.

Examples

use heapless::FnvIndexSet;

let mut a: FnvIndexSet<_, 16> = [1, 2, 3].iter().cloned().collect();
let mut b: FnvIndexSet<_, 16> = [4, 2, 3, 4].iter().cloned().collect();

// Print 1, 2, 3, 4 in that order.
for x in a.union(&b) {
    println!("{}", x);
}

let union: FnvIndexSet<_, 16> = a.union(&b).collect();
assert_eq!(union, [1, 2, 3, 4].iter().collect::<FnvIndexSet<_, 16>>());

pub fn len(&self) -> usize

Returns the number of elements in the set.

Examples

use heapless::FnvIndexSet;

let mut v: FnvIndexSet<_, 16> = FnvIndexSet::new();
assert_eq!(v.len(), 0);
v.insert(1).unwrap();
assert_eq!(v.len(), 1);

pub fn is_empty(&self) -> bool

Returns true if the set contains no elements.

Examples

use heapless::FnvIndexSet;

let mut v: FnvIndexSet<_, 16> = FnvIndexSet::new();
assert!(v.is_empty());
v.insert(1).unwrap();
assert!(!v.is_empty());

pub fn clear(&mut self)

Clears the set, removing all values.

Examples

use heapless::FnvIndexSet;

let mut v: FnvIndexSet<_, 16> = FnvIndexSet::new();
v.insert(1).unwrap();
v.clear();
assert!(v.is_empty());

pub fn contains<Q>(&self, value: &Q) -> bool

where T: Borrow<Q>, Q: ?Sized + Eq + Hash,

Returns true if the set contains a value.

The value may be any borrowed form of the set’s value type, but Hash and Eq on the borrowed form must match those for the value type.

Examples

use heapless::FnvIndexSet;

let set: FnvIndexSet<_, 16> = [1, 2, 3].iter().cloned().collect();
assert_eq!(set.contains(&1), true);
assert_eq!(set.contains(&4), false);

pub fn is_disjoint<S2, const N2: usize>( &self, other: &IndexSet<T, S2, N2>, ) -> bool

where S2: BuildHasher,

Returns true if self has no elements in common with other. This is equivalent to checking for an empty intersection.

Examples

use heapless::FnvIndexSet;

let a: FnvIndexSet<_, 16> = [1, 2, 3].iter().cloned().collect();
let mut b = FnvIndexSet::<_, 16>::new();

assert_eq!(a.is_disjoint(&b), true);
b.insert(4).unwrap();
assert_eq!(a.is_disjoint(&b), true);
b.insert(1).unwrap();
assert_eq!(a.is_disjoint(&b), false);

pub fn is_subset<S2, const N2: usize>( &self, other: &IndexSet<T, S2, N2>, ) -> bool

where S2: BuildHasher,

Returns true if the set is a subset of another, i.e. other contains at least all the values in self.

Examples

use heapless::FnvIndexSet;

let sup: FnvIndexSet<_, 16> = [1, 2, 3].iter().cloned().collect();
let mut set = FnvIndexSet::<_, 16>::new();

assert_eq!(set.is_subset(&sup), true);
set.insert(2).unwrap();
assert_eq!(set.is_subset(&sup), true);
set.insert(4).unwrap();
assert_eq!(set.is_subset(&sup), false);

pub fn is_superset<S2, const N2: usize>( &self, other: &IndexSet<T, S2, N2>, ) -> bool

where S2: BuildHasher,

Examples

use heapless::FnvIndexSet;

let sub: FnvIndexSet<_, 16> = [1, 2].iter().cloned().collect();
let mut set = FnvIndexSet::<_, 16>::new();

assert_eq!(set.is_superset(&sub), false);

set.insert(0).unwrap();
set.insert(1).unwrap();
assert_eq!(set.is_superset(&sub), false);

set.insert(2).unwrap();
assert_eq!(set.is_superset(&sub), true);

pub fn insert(&mut self, value: T) -> Result<bool, T>

Adds a value to the set.

If the set did not have this value present, true is returned.

If the set did have this value present, false is returned.

Examples

use heapless::FnvIndexSet;

let mut set = FnvIndexSet::<_, 16>::new();

assert_eq!(set.insert(2).unwrap(), true);
assert_eq!(set.insert(2).unwrap(), false);
assert_eq!(set.len(), 1);

pub fn remove<Q>(&mut self, value: &Q) -> bool

where T: Borrow<Q>, Q: ?Sized + Eq + Hash,

Removes a value from the set. Returns true if the value was present in the set.

The value may be any borrowed form of the set’s value type, but Hash and Eq on the borrowed form must match those for the value type.

Examples

use heapless::FnvIndexSet;

let mut set = FnvIndexSet::<_, 16>::new();

set.insert(2).unwrap();
assert_eq!(set.remove(&2), true);
assert_eq!(set.remove(&2), false);

Trait Implementations

impl<T, S, const N: usize> Clone for IndexSet<T, S, N>

where T: Eq + Hash + Clone, 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<T, S, const N: usize> Debug for IndexSet<T, S, N>

where T: Eq + Hash + Debug, S: BuildHasher,

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

Formats the value using the given formatter.

impl<T, S, const N: usize> Default for IndexSet<T, S, N>

where T: Eq + Hash, S: BuildHasher + Default,

fn default() -> Self

Returns the “default value” for a type.

impl<'a, T, S, const N: usize> Extend<&'a T> for IndexSet<T, S, N>

where T: 'a + Eq + Hash + Copy, S: BuildHasher,

fn extend<I>(&mut self, iterable: I)

where I: IntoIterator<Item = &'a T>,

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<T, S, const N: usize> Extend<T> for IndexSet<T, S, N>

where T: Eq + Hash, S: BuildHasher,

fn extend<I>(&mut self, iterable: I)

where I: IntoIterator<Item = T>,

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<T, S, const N: usize> FromIterator<T> for IndexSet<T, S, N>

where T: Eq + Hash, S: BuildHasher + Default,

fn from_iter<I>(iter: I) -> Self

where I: IntoIterator<Item = T>,

Creates a value from an iterator.

impl<'a, T, S, const N: usize> IntoIterator for &'a IndexSet<T, S, N>

where T: Eq + Hash, S: BuildHasher,

type Item = &'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) -> Self::IntoIter

Creates an iterator from a value.

impl<T, S1, S2, const N1: usize, const N2: usize> PartialEq<IndexSet<T, S2, N2>> for IndexSet<T, S1, N1>

where T: Eq + Hash, S1: BuildHasher, S2: BuildHasher,

fn eq(&self, other: &IndexSet<T, S2, N2>) -> 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.