Struct std::collections::hash_map::VacantEntry

1.0.0 · source ·
pub struct VacantEntry<'a, K: 'a, V: 'a> { /* private fields */ }
Expand description

HashMap 中空闲条目的视图。 它是 Entry 枚举的一部分。

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impl<'a, K: 'a, V: 'a> VacantEntry<'a, K, V>

1.10.0 · source

pub fn key(&self) -> &K

获取对通过 VacantEntry 插入值时将使用的键的引用。

Examples
use std::collections::HashMap;

let mut map: HashMap<&str, u32> = HashMap::new();
assert_eq!(map.entry("poneyland").key(), &"poneyland");
Run
1.12.0 · source

pub fn into_key(self) -> K

取得键的所有权。

Examples
use std::collections::HashMap;
use std::collections::hash_map::Entry;

let mut map: HashMap<&str, u32> = HashMap::new();

if let Entry::Vacant(v) = map.entry("poneyland") {
    v.into_key();
}
Run
source

pub fn insert(self, value: V) -> &'a mut V

VacantEntry 的键设置条目的值,并返回对它的可变引用。

Examples
use std::collections::HashMap;
use std::collections::hash_map::Entry;

let mut map: HashMap<&str, u32> = HashMap::new();

if let Entry::Vacant(o) = map.entry("poneyland") {
    o.insert(37);
}
assert_eq!(map["poneyland"], 37);
Run
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pub fn insert_entry(self, value: V) -> OccupiedEntry<'a, K, V>

🔬This is a nightly-only experimental API. (entry_insert #65225)

使用 VacantEntry 的键设置条目的值,并返回 OccupiedEntry

Examples
#![feature(entry_insert)]
use std::collections::HashMap;
use std::collections::hash_map::Entry;

let mut map: HashMap<&str, u32> = HashMap::new();

if let Entry::Vacant(o) = map.entry("poneyland") {
    o.insert_entry(37);
}
assert_eq!(map["poneyland"], 37);
Run

Trait Implementations§

1.12.0 · source§

impl<K: Debug, V> Debug for VacantEntry<'_, K, V>

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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> RefUnwindSafe for VacantEntry<'a, K, V>where K: RefUnwindSafe, V: RefUnwindSafe,

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

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

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

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impl<'a, K, V> !UnwindSafe for VacantEntry<'a, K, V>

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。