Home Original page

Bound in core::ops - Rust

Enum Bound 

1.26.0 · Source 

pub enum Bound<T> {
    Included(T),
    Excluded(T),
    Unbounded,
}
Expand description

An endpoint of a range of keys.

§Examples

Bounds are range endpoints:

use std::ops::Bound::*;
use std::ops::RangeBounds;

assert_eq!((..100).start_bound(), Unbounded);
assert_eq!((1..12).start_bound(), Included(&1));
assert_eq!((1..12).end_bound(), Excluded(&12));

Using a tuple of Bounds as an argument to BTreeMap::range. Note that in most cases, it’s better to use range syntax (1..5) instead.

use std::collections::BTreeMap;
use std::ops::Bound::{Excluded, Included, Unbounded};

let mut map = BTreeMap::new();
map.insert(3, "a");
map.insert(5, "b");
map.insert(8, "c");

for (key, value) in map.range((Excluded(3), Included(8))) {
    println!("{key}: {value}");
}

assert_eq!(Some((&3, &"a")), map.range((Unbounded, Included(5))).next());
§1.26.0

An inclusive bound.

§1.26.0

An exclusive bound.

§1.26.0

An infinite endpoint. Indicates that there is no bound in this direction.

Source§
1.65.0 (const: unstable) · Source

Converts from &Bound<T> to Bound<&T>.

Source

🔬This is a nightly-only experimental API. (bound_as_ref #80996)

Converts from &mut Bound<T> to Bound<&mut T>.

1.77.0 · Source

Maps a Bound<T> to a Bound<U> by applying a function to the contained value (including both Included and Excluded), returning a Bound of the same kind.

§Examples
use std::ops::Bound::*;

let bound_string = Included("Hello, World!");

assert_eq!(bound_string.map(|s| s.len()), Included(13));
use std::ops::Bound;
use Bound::*;

let unbounded_string: Bound<String> = Unbounded;

assert_eq!(unbounded_string.map(|s| s.len()), Unbounded);
Source§
Source

🔬This is a nightly-only experimental API. (bound_copied #145966)

Map a Bound<&T> to a Bound<T> by copying the contents of the bound.

§Examples
#![feature(bound_copied)]

use std::ops::Bound::*;
use std::ops::RangeBounds;

assert_eq!((1..12).start_bound(), Included(&1));
assert_eq!((1..12).start_bound().copied(), Included(1));
Source§
1.55.0 (const: unstable) · Source

Map a Bound<&T> to a Bound<T> by cloning the contents of the bound.

§Examples
use std::ops::Bound::*;
use std::ops::RangeBounds;

let a1 = String::from("a");
let (a2, a3, a4) = (a1.clone(), a1.clone(), a1.clone());

assert_eq!(Included(&a1), (a2..).start_bound());
assert_eq!(Included(a3), (a4..).start_bound().cloned());