Struct NoOrder 

#[repr(transparent)]
pub struct NoOrder<T>(pub T);

A helper struct for no ordering, where every instance of NoOrder is equivalent to any other NoOrder.

This struct is a helper to be used with data structures like std::collections::BinaryHeap or std::collections::HashSet, and can be used to ignore ordering or hashing of part of a key.

Can be used for faster performance or when an key does not implement std::cmp::Ord or std::hash::Hash, and is not relavant.

Examples

use no_order::NoOrder;
use std::collections::BinaryHeap;
use std::collections::HashSet;

// Any NoOrder is equivalent to any other.
assert_eq!(NoOrder(1), NoOrder(2));
assert_eq!(NoOrder(1), NoOrder(1));

// This means that they also share the same key.
let set = HashSet::from([NoOrder(1), NoOrder(1), NoOrder(2), NoOrder(3)]);
assert_eq!(set.len(), 1);

// And can be used to ignore the the second value in a tuple.
let set_tuple = HashSet::from([(1, NoOrder(1)), (2, NoOrder(1)), (2, NoOrder(2))]);
assert_eq!(set_tuple.len(), 2);

// When used in a heap or tree like data structure, we can store extra data without sorting on it.
// This means that we can use types that do not traditionally implement Ord.
let mut heap = BinaryHeap::new();
heap.push((2, NoOrder(1.24)));
heap.push((1, NoOrder(2.15)));
heap.push((2, NoOrder(3.74)));
heap.push((2, NoOrder(2.96)));

// It only acts as a max heap on the first value,
// and the ordering on the second value is undefiend.
while let Some((a, NoOrder(b))) = heap.pop() {
    println!("{a}, {b}");
}

Tuple Fields

0: T

Trait Implementations

impl<T: Clone> Clone for NoOrder<T>

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug> Debug for NoOrder<T>

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

Formats the value using the given formatter.

impl<T: Default> Default for NoOrder<T>

fn default() -> NoOrder<T>

Returns the “default value” for a type.

impl<T> Hash for NoOrder<T>

fn hash<H: Hasher>(&self, _: &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<T> Ord for NoOrder<T>

fn cmp(&self, _: &Self) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl<T> PartialEq for NoOrder<T>

fn eq(&self, _: &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<T> PartialOrd for NoOrder<T>

fn partial_cmp(&self, _: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl<T: Copy> Copy for NoOrder<T>

impl<T> Eq for NoOrder<T>