1.0.0[][src]Enum std::cmp::Ordering

pub enum Ordering {
    Less,
    Equal,
    Greater,
}

An Ordering is the result of a comparison between two values.

Examples

use std::cmp::Ordering;

let result = 1.cmp(&2);
assert_eq!(Ordering::Less, result);

let result = 1.cmp(&1);
assert_eq!(Ordering::Equal, result);

let result = 2.cmp(&1);
assert_eq!(Ordering::Greater, result);Run

Variants

Less

An ordering where a compared value is less [than another].

Equal

An ordering where a compared value is equal [to another].

Greater

An ordering where a compared value is greater [than another].

Methods

impl Ordering[src]

pub fn reverse(self) -> Ordering[src]

Reverses the Ordering.

  • Less becomes Greater.
  • Greater becomes Less.
  • Equal becomes Equal.

Examples

Basic behavior:

use std::cmp::Ordering;

assert_eq!(Ordering::Less.reverse(), Ordering::Greater);
assert_eq!(Ordering::Equal.reverse(), Ordering::Equal);
assert_eq!(Ordering::Greater.reverse(), Ordering::Less);Run

This method can be used to reverse a comparison:

let mut data: &mut [_] = &mut [2, 10, 5, 8];

// sort the array from largest to smallest.
data.sort_by(|a, b| a.cmp(b).reverse());

let b: &mut [_] = &mut [10, 8, 5, 2];
assert!(data == b);Run

pub fn then(self, other: Ordering) -> Ordering
1.17.0
[src]

Chains two orderings.

Returns self when it's not Equal. Otherwise returns other.

Examples

use std::cmp::Ordering;

let result = Ordering::Equal.then(Ordering::Less);
assert_eq!(result, Ordering::Less);

let result = Ordering::Less.then(Ordering::Equal);
assert_eq!(result, Ordering::Less);

let result = Ordering::Less.then(Ordering::Greater);
assert_eq!(result, Ordering::Less);

let result = Ordering::Equal.then(Ordering::Equal);
assert_eq!(result, Ordering::Equal);

let x: (i64, i64, i64) = (1, 2, 7);
let y: (i64, i64, i64) = (1, 5, 3);
let result = x.0.cmp(&y.0).then(x.1.cmp(&y.1)).then(x.2.cmp(&y.2));

assert_eq!(result, Ordering::Less);Run

pub fn then_with<F>(self, f: F) -> Ordering where
    F: FnOnce() -> Ordering
1.17.0
[src]

Chains the ordering with the given function.

Returns self when it's not Equal. Otherwise calls f and returns the result.

Examples

use std::cmp::Ordering;

let result = Ordering::Equal.then_with(|| Ordering::Less);
assert_eq!(result, Ordering::Less);

let result = Ordering::Less.then_with(|| Ordering::Equal);
assert_eq!(result, Ordering::Less);

let result = Ordering::Less.then_with(|| Ordering::Greater);
assert_eq!(result, Ordering::Less);

let result = Ordering::Equal.then_with(|| Ordering::Equal);
assert_eq!(result, Ordering::Equal);

let x: (i64, i64, i64) = (1, 2, 7);
let y: (i64, i64, i64)  = (1, 5, 3);
let result = x.0.cmp(&y.0).then_with(|| x.1.cmp(&y.1)).then_with(|| x.2.cmp(&y.2));

assert_eq!(result, Ordering::Less);Run

Trait Implementations

impl Clone for Ordering[src]

fn clone_from(&mut self, source: &Self)[src]

Performs copy-assignment from source. Read more

impl PartialOrd<Ordering> for Ordering[src]

#[must_use]
fn lt(&self, other: &Rhs) -> bool
[src]

This method tests less than (for self and other) and is used by the < operator. Read more

#[must_use]
fn le(&self, other: &Rhs) -> bool
[src]

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more

#[must_use]
fn gt(&self, other: &Rhs) -> bool
[src]

This method tests greater than (for self and other) and is used by the > operator. Read more

#[must_use]
fn ge(&self, other: &Rhs) -> bool
[src]

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more

impl Ord for Ordering[src]

fn max(self, other: Self) -> Self
1.21.0
[src]

Compares and returns the maximum of two values. Read more

fn min(self, other: Self) -> Self
1.21.0
[src]

Compares and returns the minimum of two values. Read more

impl Eq for Ordering[src]

impl PartialEq<Ordering> for Ordering[src]

#[must_use]
fn ne(&self, other: &Rhs) -> bool
[src]

This method tests for !=.

impl Debug for Ordering[src]

impl Hash for Ordering[src]

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher
1.3.0
[src]

Feeds a slice of this type into the given [Hasher]. Read more

impl Copy for Ordering[src]

Auto Trait Implementations

impl Send for Ordering

impl Sync for Ordering

Blanket Implementations

impl<T> From for T[src]

impl<T, U> TryFrom for T where
    U: Into<T>, 
[src]

type Error = !

🔬 This is a nightly-only experimental API. (try_from #33417)

The type returned in the event of a conversion error.

impl<T, U> TryInto for T where
    U: TryFrom<T>, 
[src]

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

🔬 This is a nightly-only experimental API. (try_from #33417)

The type returned in the event of a conversion error.

impl<T, U> Into for T where
    U: From<T>, 
[src]

impl<T> Borrow for T where
    T: ?Sized
[src]

impl<T> BorrowMut for T where
    T: ?Sized
[src]

impl<T> Any for T where
    T: 'static + ?Sized
[src]

impl<T> ToOwned for T where
    T: Clone
[src]

type Owned = T