Struct heapless::IndexSet

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

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§

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

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pub const fn new() -> Self

Creates an empty IndexSet

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

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

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

Examples
use heapless::FnvIndexSet;

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

// Will print in insertion order: a, b
for x in set.iter() {
    println!("{}", x);
}
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pub fn first(&self) -> Option<&T>

Get the first value

Computes in O(1) time

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

Get the last value

Computes in O(1) time

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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);
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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());
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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());
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impl<T, S, const N: usize> IndexSet<T, S, N>
where T: Eq + Hash, S: BuildHasher,

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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>>());
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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.
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>>());
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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>>());
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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>>());
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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);
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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);
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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);
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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);
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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);
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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);
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pub fn retain<F>(&mut self, f: F)
where F: FnMut(&T) -> bool,

Retains only the elements specified by the predicate.

In other words, remove all elements e for which f(&e) returns false.

Trait Implementations§

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

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fn clone(&self) -> Self

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl<T, S, const N: usize> Debug for IndexSet<T, S, N>
where T: Debug,

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

Formats the value using the given formatter. Read more
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impl<T, S, const N: usize> Default for IndexSet<T, S, N>
where S: Default,

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fn default() -> Self

Returns the “default value” for a type. Read more
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impl<'a, T, S, const N: usize> Extend<&'a T> for IndexSet<T, S, N>
where T: 'a + Eq + Hash + Copy, S: BuildHasher,

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fn extend<I>(&mut self, iterable: I)
where I: IntoIterator<Item = &'a T>,

Extends a collection with the contents of an iterator. Read more
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fn extend_one(&mut self, item: A)

🔬This is a nightly-only experimental API. (extend_one)
Extends a collection with exactly one element.
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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. Read more
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impl<T, S, const N: usize> Extend<T> for IndexSet<T, S, N>
where T: Eq + Hash, S: BuildHasher,

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

Extends a collection with the contents of an iterator. Read more
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fn extend_one(&mut self, item: A)

🔬This is a nightly-only experimental API. (extend_one)
Extends a collection with exactly one element.
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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. Read more
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impl<T, S, const N: usize> FromIterator<T> for IndexSet<T, S, N>
where T: Eq + Hash, S: BuildHasher + Default,

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fn from_iter<I>(iter: I) -> Self
where I: IntoIterator<Item = T>,

Creates a value from an iterator. Read more
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impl<'a, T, S, const N: usize> IntoIterator for &'a IndexSet<T, S, N>
where T: Eq + Hash, S: BuildHasher,

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type Item = &'a T

The type of the elements being iterated over.
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type IntoIter = Iter<'a, T>

Which kind of iterator are we turning this into?
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fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value. Read more
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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,

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

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

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

Auto Trait Implementations§

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

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

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

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

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

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.