Struct heapless::binary_heap::BinaryHeap
source · pub struct BinaryHeap<T, K, const N: usize> { /* private fields */ }
Expand description
A priority queue implemented with a binary heap.
This can be either a min-heap or a max-heap.
It is a logic error for an item to be modified in such a way that the item’s ordering relative
to any other item, as determined by the Ord
trait, changes while it is in the heap. This is
normally only possible through Cell
, RefCell
, global state, I/O, or unsafe code.
use heapless::binary_heap::{BinaryHeap, Max};
let mut heap: BinaryHeap<_, Max, 8> = BinaryHeap::new();
// We can use peek to look at the next item in the heap. In this case,
// there's no items in there yet so we get None.
assert_eq!(heap.peek(), None);
// Let's add some scores...
heap.push(1).unwrap();
heap.push(5).unwrap();
heap.push(2).unwrap();
// Now peek shows the most important item in the heap.
assert_eq!(heap.peek(), Some(&5));
// We can check the length of a heap.
assert_eq!(heap.len(), 3);
// We can iterate over the items in the heap, although they are returned in
// a random order.
for x in &heap {
println!("{}", x);
}
// If we instead pop these scores, they should come back in order.
assert_eq!(heap.pop(), Some(5));
assert_eq!(heap.pop(), Some(2));
assert_eq!(heap.pop(), Some(1));
assert_eq!(heap.pop(), None);
// We can clear the heap of any remaining items.
heap.clear();
// The heap should now be empty.
assert!(heap.is_empty())
Implementations§
source§impl<T, K, const N: usize> BinaryHeap<T, K, N>
impl<T, K, const N: usize> BinaryHeap<T, K, N>
sourcepub const fn new() -> Self
pub const fn new() -> Self
Creates an empty BinaryHeap as a $K-heap.
use heapless::binary_heap::{BinaryHeap, Max};
// allocate the binary heap on the stack
let mut heap: BinaryHeap<_, Max, 8> = BinaryHeap::new();
heap.push(4).unwrap();
// allocate the binary heap in a static variable
static mut HEAP: BinaryHeap<i32, Max, 8> = BinaryHeap::new();
source§impl<T, K, const N: usize> BinaryHeap<T, K, N>
impl<T, K, const N: usize> BinaryHeap<T, K, N>
sourcepub fn clear(&mut self)
pub fn clear(&mut self)
Drops all items from the binary heap.
use heapless::binary_heap::{BinaryHeap, Max};
let mut heap: BinaryHeap<_, Max, 8> = BinaryHeap::new();
heap.push(1).unwrap();
heap.push(3).unwrap();
assert!(!heap.is_empty());
heap.clear();
assert!(heap.is_empty());
sourcepub fn len(&self) -> usize
pub fn len(&self) -> usize
Returns the length of the binary heap.
use heapless::binary_heap::{BinaryHeap, Max};
let mut heap: BinaryHeap<_, Max, 8> = BinaryHeap::new();
heap.push(1).unwrap();
heap.push(3).unwrap();
assert_eq!(heap.len(), 2);
sourcepub fn is_empty(&self) -> bool
pub fn is_empty(&self) -> bool
Checks if the binary heap is empty.
use heapless::binary_heap::{BinaryHeap, Max};
let mut heap: BinaryHeap<_, Max, 8> = BinaryHeap::new();
assert!(heap.is_empty());
heap.push(3).unwrap();
heap.push(5).unwrap();
heap.push(1).unwrap();
assert!(!heap.is_empty());
sourcepub fn iter(&self) -> Iter<'_, T>
pub fn iter(&self) -> Iter<'_, T>
Returns an iterator visiting all values in the underlying vector, in arbitrary order.
use heapless::binary_heap::{BinaryHeap, Max};
let mut heap: BinaryHeap<_, Max, 8> = BinaryHeap::new();
heap.push(1).unwrap();
heap.push(2).unwrap();
heap.push(3).unwrap();
heap.push(4).unwrap();
// Print 1, 2, 3, 4 in arbitrary order
for x in heap.iter() {
println!("{}", x);
}
sourcepub fn iter_mut(&mut self) -> IterMut<'_, T>
pub fn iter_mut(&mut self) -> IterMut<'_, T>
Returns a mutable iterator visiting all values in the underlying vector, in arbitrary order.
WARNING Mutating the items in the binary heap can leave the heap in an inconsistent state.
sourcepub fn peek(&self) -> Option<&T>
pub fn peek(&self) -> Option<&T>
Returns the top (greatest if max-heap, smallest if min-heap) item in the binary heap, or None if it is empty.
use heapless::binary_heap::{BinaryHeap, Max};
let mut heap: BinaryHeap<_, Max, 8> = BinaryHeap::new();
assert_eq!(heap.peek(), None);
heap.push(1).unwrap();
heap.push(5).unwrap();
heap.push(2).unwrap();
assert_eq!(heap.peek(), Some(&5));
sourcepub fn peek_mut(&mut self) -> Option<PeekMut<'_, T, K, N>>
pub fn peek_mut(&mut self) -> Option<PeekMut<'_, T, K, N>>
Returns a mutable reference to the greatest item in the binary heap, or
None
if it is empty.
Note: If the PeekMut
value is leaked, the heap may be in an
inconsistent state.
§Examples
Basic usage:
use heapless::binary_heap::{BinaryHeap, Max};
let mut heap: BinaryHeap<_, Max, 8> = BinaryHeap::new();
assert!(heap.peek_mut().is_none());
heap.push(1);
heap.push(5);
heap.push(2);
{
let mut val = heap.peek_mut().unwrap();
*val = 0;
}
assert_eq!(heap.peek(), Some(&2));
sourcepub fn pop(&mut self) -> Option<T>
pub fn pop(&mut self) -> Option<T>
Removes the top (greatest if max-heap, smallest if min-heap) item from the binary heap and returns it, or None if it is empty.
use heapless::binary_heap::{BinaryHeap, Max};
let mut heap: BinaryHeap<_, Max, 8> = BinaryHeap::new();
heap.push(1).unwrap();
heap.push(3).unwrap();
assert_eq!(heap.pop(), Some(3));
assert_eq!(heap.pop(), Some(1));
assert_eq!(heap.pop(), None);
sourcepub unsafe fn pop_unchecked(&mut self) -> T
pub unsafe fn pop_unchecked(&mut self) -> T
Removes the top (greatest if max-heap, smallest if min-heap) item from the binary heap and returns it, without checking if the binary heap is empty.
sourcepub fn push(&mut self, item: T) -> Result<(), T>
pub fn push(&mut self, item: T) -> Result<(), T>
Pushes an item onto the binary heap.
use heapless::binary_heap::{BinaryHeap, Max};
let mut heap: BinaryHeap<_, Max, 8> = BinaryHeap::new();
heap.push(3).unwrap();
heap.push(5).unwrap();
heap.push(1).unwrap();
assert_eq!(heap.len(), 3);
assert_eq!(heap.peek(), Some(&5));
sourcepub unsafe fn push_unchecked(&mut self, item: T)
pub unsafe fn push_unchecked(&mut self, item: T)
Pushes an item onto the binary heap without first checking if it’s full.