Enum core::cmp::Ordering

1.0.0 · source ·

#[repr(i8)]pub enum Ordering {
    Less,
    Equal,
    Greater,
}

Expand description

Ordering 是两个值之间比较的结果。

Examples

use std::cmp::Ordering;

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

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

assert_eq!(2.cmp(&1), Ordering::Greater);

Run

Variants§

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Less

比较值小于另一个值的排序。

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Equal

比较值等于另一个的排序。

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Greater

比较值大于另一个值的排序。

Implementations§

source §

impl Ordering

1.53.0 (const: 1.53.0) · source

pub const fn is_eq(self) -> bool

如果排序的是 Equal 变体，则返回 true。

Examples

use std::cmp::Ordering;

assert_eq!(Ordering::Less.is_eq(), false);
assert_eq!(Ordering::Equal.is_eq(), true);
assert_eq!(Ordering::Greater.is_eq(), false);

Run

1.53.0 (const: 1.53.0) · source

pub const fn is_ne(self) -> bool

如果排序的不是 Equal 变体，则返回 true。

Examples

use std::cmp::Ordering;

assert_eq!(Ordering::Less.is_ne(), true);
assert_eq!(Ordering::Equal.is_ne(), false);
assert_eq!(Ordering::Greater.is_ne(), true);

Run

1.53.0 (const: 1.53.0) · source

pub const fn is_lt(self) -> bool

如果排序的是 Less 变体，则返回 true。

Examples

use std::cmp::Ordering;

assert_eq!(Ordering::Less.is_lt(), true);
assert_eq!(Ordering::Equal.is_lt(), false);
assert_eq!(Ordering::Greater.is_lt(), false);

Run

1.53.0 (const: 1.53.0) · source

pub const fn is_gt(self) -> bool

如果排序的是 Greater 变体，则返回 true。

Examples

use std::cmp::Ordering;

assert_eq!(Ordering::Less.is_gt(), false);
assert_eq!(Ordering::Equal.is_gt(), false);
assert_eq!(Ordering::Greater.is_gt(), true);

Run

1.53.0 (const: 1.53.0) · source

pub const fn is_le(self) -> bool

如果排序的是 Less 或 Equal 变体，则返回 true。

Examples

use std::cmp::Ordering;

assert_eq!(Ordering::Less.is_le(), true);
assert_eq!(Ordering::Equal.is_le(), true);
assert_eq!(Ordering::Greater.is_le(), false);

Run

1.53.0 (const: 1.53.0) · source

pub const fn is_ge(self) -> bool

如果排序的是 Greater 或 Equal 变体，则返回 true。

Examples

use std::cmp::Ordering;

assert_eq!(Ordering::Less.is_ge(), false);
assert_eq!(Ordering::Equal.is_ge(), true);
assert_eq!(Ordering::Greater.is_ge(), true);

Run

const: 1.48.0 · source

pub const fn reverse(self) -> Ordering

反转 Ordering。

Less 变成 Greater。
Greater 变成 Less。
Equal 变成 Equal。

Examples

基本行为：

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

此方法可用于反转比较：

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

// 从最大到最小对数组进行排序。
data.sort_by(|a, b| a.cmp(b).reverse());

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

Run

1.17.0 (const: 1.48.0) · source

pub const fn then(self, other: Ordering) -> Ordering

链接两个排序。

如果不是 Equal，则返回 self。否则返回 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

1.17.0 · source

pub fn then_with<F: FnOnce() -> Ordering>(self, f: F) -> Ordering

用给定的函数链接顺序。

如果不是 Equal，则返回 self。否则，调用 f 并返回结果。

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);