Struct alloc::collections::btree_map::OccupiedEntry

1.0.0 · source ·
pub struct OccupiedEntry<'a, K, V, A: Allocator + Clone = Global> { /* private fields */ }
Expand description

BTreeMap 中已占用条目的视图。 它是 Entry 枚举的一部分。

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impl<'a, K: Ord, V, A: Allocator + Clone> OccupiedEntry<'a, K, V, A>

1.10.0 · source

pub fn key(&self) -> &K

获取条目中键的引用。

Examples
use std::collections::BTreeMap;

let mut map: BTreeMap<&str, usize> = BTreeMap::new();
map.entry("poneyland").or_insert(12);
assert_eq!(map.entry("poneyland").key(), &"poneyland");
Run
1.12.0 · source

pub fn remove_entry(self) -> (K, V)

从 map 获取键和值的所有权。

Examples
use std::collections::BTreeMap;
use std::collections::btree_map::Entry;

let mut map: BTreeMap<&str, usize> = BTreeMap::new();
map.entry("poneyland").or_insert(12);

if let Entry::Occupied(o) = map.entry("poneyland") {
    // 我们从 map 中删除了这个条目。
    o.remove_entry();
}

// 如果现在尝试获取该值,它将为 panic:
// println!("{}", map["poneyland"]);
Run
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pub fn get(&self) -> &V

获取条目中值的引用。

Examples
use std::collections::BTreeMap;
use std::collections::btree_map::Entry;

let mut map: BTreeMap<&str, usize> = BTreeMap::new();
map.entry("poneyland").or_insert(12);

if let Entry::Occupied(o) = map.entry("poneyland") {
    assert_eq!(o.get(), &12);
}
Run
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pub fn get_mut(&mut self) -> &mut V

获取条目中的值的可变引用。

如果您需要引用可能比销毁 Entry 值还长的 OccupiedEntry,请参阅 into_mut

Examples
use std::collections::BTreeMap;
use std::collections::btree_map::Entry;

let mut map: BTreeMap<&str, usize> = BTreeMap::new();
map.entry("poneyland").or_insert(12);

assert_eq!(map["poneyland"], 12);
if let Entry::Occupied(mut o) = map.entry("poneyland") {
    *o.get_mut() += 10;
    assert_eq!(*o.get(), 22);

    // 我们可以多次使用同一个 Entry。
    *o.get_mut() += 2;
}
assert_eq!(map["poneyland"], 24);
Run
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pub fn into_mut(self) -> &'a mut V

将条目转换为其值的可变引用。

如果需要多次引用 OccupiedEntry,请参见 get_mut

Examples
use std::collections::BTreeMap;
use std::collections::btree_map::Entry;

let mut map: BTreeMap<&str, usize> = BTreeMap::new();
map.entry("poneyland").or_insert(12);

assert_eq!(map["poneyland"], 12);
if let Entry::Occupied(o) = map.entry("poneyland") {
    *o.into_mut() += 10;
}
assert_eq!(map["poneyland"], 22);
Run
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pub fn insert(&mut self, value: V) -> V

使用 OccupiedEntry 键设置条目的值,并返回条目的旧值。

Examples
use std::collections::BTreeMap;
use std::collections::btree_map::Entry;

let mut map: BTreeMap<&str, usize> = BTreeMap::new();
map.entry("poneyland").or_insert(12);

if let Entry::Occupied(mut o) = map.entry("poneyland") {
    assert_eq!(o.insert(15), 12);
}
assert_eq!(map["poneyland"], 15);
Run
source

pub fn remove(self) -> V

从 map 中获取条目的值,并将其返回。

Examples
use std::collections::BTreeMap;
use std::collections::btree_map::Entry;

let mut map: BTreeMap<&str, usize> = BTreeMap::new();
map.entry("poneyland").or_insert(12);

if let Entry::Occupied(o) = map.entry("poneyland") {
    assert_eq!(o.remove(), 12);
}
// 如果我们尝试获得 `poneyland` 的值,则它将为 panic:
// println!("{}", map["poneyland"]);
Run

Trait Implementations§

1.12.0 · source§

impl<K: Debug + Ord, V: Debug, A: Allocator + Clone> Debug for OccupiedEntry<'_, K, V, A>

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

使用给定的格式化程序格式化该值。 Read more

Auto Trait Implementations§

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impl<'a, K, V, A> RefUnwindSafe for OccupiedEntry<'a, K, V, A>where A: RefUnwindSafe, K: RefUnwindSafe, V: RefUnwindSafe,

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impl<'a, K, V, A> Send for OccupiedEntry<'a, K, V, A>where A: Send, K: Send, V: Send,

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impl<'a, K, V, A> Sync for OccupiedEntry<'a, K, V, A>where A: Sync, K: Sync, V: Sync,

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impl<'a, K, V, A> Unpin for OccupiedEntry<'a, K, V, A>where A: Unpin,

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impl<'a, K, V, A = Global> !UnwindSafe for OccupiedEntry<'a, K, V, A>

Blanket Implementations§

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impl<T> Any for Twhere T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

获取 selfTypeIdRead more
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impl<T> Borrow<T> for Twhere T: ?Sized,

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fn borrow(&self) -> &T

从拥有的值中一成不变地借用。 Read more
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impl<T> BorrowMut<T> for Twhere T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

从拥有的值中借用。 Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

返回未更改的参数。

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impl<T, U> Into<U> for Twhere U: From<T>,

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fn into(self) -> U

调用 U::from(self)

也就是说,这种转换是 From<T> for U 实现选择执行的任何操作。

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impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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type Error = Infallible

发生转换错误时返回的类型。
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

执行转换。
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impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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

发生转换错误时返回的类型。
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

执行转换。