Enum core::ops::Bound

1.17.0 · 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));

Run

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());

Run

Variants

`Included(T)`

An inclusive bound.

`Excluded(T)`

An exclusive bound.

`Unbounded`

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

Implementations

source

impl<T> Bound<T>

source

pub fn as_ref(&self) -> Bound<&T>

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

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

source

pub fn as_mut(&mut self) -> Bound<&mut T>

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

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

source

pub fn map<U, F: FnOnce(T) -> U>(self, f: F) -> Bound

🔬This is a nightly-only experimental API. (bound_map #86026)

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

Examples

#![feature(bound_map)]
use std::ops::Bound::*;

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

assert_eq!(bound_string.map(|s| s.len()), Included(13));

Run

#![feature(bound_map)]
use std::ops::Bound;
use Bound::*;

let unbounded_string: Bound<String> = Unbounded;

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

Run

source

impl<T: Clone> Bound<&T>

1.55.0 · source

pub fn cloned(self) -> Bound<T>

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

Examples

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

assert_eq!((1..12).start_bound(), Included(&1));
assert_eq!((1..12).start_bound().cloned(), Included(1));