# 1.0.0[−][src]Enum std::collections::hash_map::Entry

    pub enum Entry<'a, K: 'a, V: 'a> {
        Occupied(OccupiedEntry<'a, K, V>),
        Vacant(VacantEntry<'a, K, V>),
    }

A view into a single entry in a map, which may either be vacant or occupied.

This `enum` is constructed from the `entry` method on `HashMap`.

## Variants

`Occupied(OccupiedEntry<'a, K, V>)`

An occupied entry.

`Vacant(VacantEntry<'a, K, V>)`

A vacant entry.

## Methods

### `impl<'a, K, V> Entry<'a, K, V>`[src]

####
ⓘImportant traits for &'_ mut F

### Important traits for &'_ mut F

`impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'_, R: Read + ?Sized> Read for &'_ mut Rimpl<'_, W: Write + ?Sized> Write for &'_ mut W`
`pub fn or_insert(self, default: V) -> &'a mut V`[src]

Ensures a value is in the entry by inserting the default if empty, and returns a mutable reference to the value in the entry.

# Examples

    use std::collections::HashMap;

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

    map.entry("poneyland").or_insert(3);
    assert_eq!(map["poneyland"], 3);

    *map.entry("poneyland").or_insert(10) *= 2;
    assert_eq!(map["poneyland"], 6);Run

####
ⓘImportant traits for &'_ mut F

### Important traits for &'_ mut F

`impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'_, R: Read + ?Sized> Read for &'_ mut Rimpl<'_, W: Write + ?Sized> Write for &'_ mut W`
`pub fn or_insert_with<F: FnOnce() -> V>(self, default: F) -> &'a mut V`[src]

Ensures a value is in the entry by inserting the result of the default function if empty, and returns a mutable reference to the value in the entry.

# Examples

    use std::collections::HashMap;

    let mut map: HashMap<&str, String> = HashMap::new();
    let s = "hoho".to_string();

    map.entry("poneyland").or_insert_with(|| s);

    assert_eq!(map["poneyland"], "hoho".to_string());Run

####
ⓘImportant traits for &'_ mut F

### Important traits for &'_ mut F

`impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'_, R: Read + ?Sized> Read for &'_ mut Rimpl<'_, W: Write + ?Sized> Write for &'_ mut W`
`pub fn key(&self) -> &K` 1.10.0[src]

Returns a reference to this entry's key.

# Examples

    use std::collections::HashMap;

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

#### `pub fn and_modify<F>(self, f: F) -> Self where
F: FnOnce(&mut V),` 1.26.0[src]

Provides in-place mutable access to an occupied entry before any potential inserts into the map.

# Examples

    use std::collections::HashMap;

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

    map.entry("poneyland")
       .and_modify(|e| { *e += 1 })
       .or_insert(42);
    assert_eq!(map["poneyland"], 42);

    map.entry("poneyland")
       .and_modify(|e| { *e += 1 })
       .or_insert(42);
    assert_eq!(map["poneyland"], 43);Run

### `impl<'a, K, V: Default> Entry<'a, K, V>`[src]

####
ⓘImportant traits for &'_ mut F

### Important traits for &'_ mut F

`impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'_, R: Read + ?Sized> Read for &'_ mut Rimpl<'_, W: Write + ?Sized> Write for &'_ mut W`
`pub fn or_default(self) -> &'a mut V` 1.28.0[src]

Ensures a value is in the entry by inserting the default value if empty, and returns a mutable reference to the value in the entry.

# Examples

    use std::collections::HashMap;

    let mut map: HashMap<&str, Option<u32>> = HashMap::new();
    map.entry("poneyland").or_default();

    assert_eq!(map["poneyland"], None);Run

## Trait Implementations

### `impl<'_, K: Debug, V: Debug> Debug for Entry<'_, K, V>`1.12.0[src]

#### `fn fmt(&self, f: &mut Formatter) -> Result`[src]

Formats the value using the given formatter. Read more

## Auto Trait Implementations

### `impl<'a, K, V> !UnwindSafe for Entry<'a, K, V>`

### `impl<'a, K, V> RefUnwindSafe for Entry<'a, K, V> where
K: RefUnwindSafe,
V: RefUnwindSafe,`

### `impl<'a, K, V> Unpin for Entry<'a, K, V> where
K: Unpin,
V: Unpin,`

### `impl<'a, K, V> Send for Entry<'a, K, V> where
K: Send,
V: Send,`

### `impl<'a, K, V> Sync for Entry<'a, K, V> where
K: Sync,
V: Sync,`

## Blanket Implementations

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

#### `fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>`[src]

Performs the conversion.

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `fn into(self) -> U`[src]

Performs the conversion.

### `impl<T> From<T> for T`[src]

#### `fn from(t: T) -> T`[src]

Performs the conversion.

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

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

The type returned in the event of a conversion error.

#### `fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>`[src]

Performs the conversion.

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

####
ⓘImportant traits for &'_ mut F

### Important traits for &'_ mut F

`impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'_, R: Read + ?Sized> Read for &'_ mut Rimpl<'_, W: Write + ?Sized> Write for &'_ mut W`
`fn borrow(&self) -> &T`[src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

####
ⓘImportant traits for &'_ mut F

### Important traits for &'_ mut F

`impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'_, R: Read + ?Sized> Read for &'_ mut Rimpl<'_, W: Write + ?Sized> Write for &'_ mut W`
`fn borrow_mut(&mut self) -> &mut T`[src]

Mutably borrows from an owned value. Read more

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `fn type_id(&self) -> TypeId`[src]

Gets the `TypeId` of `self`. Read more

# Help

## Keyboard Shortcuts

`?`
  Show this help dialog
`S`
  Focus the search field
`↑`
  Move up in search results
`↓`
  Move down in search results
`↹`
  Switch tab
`⏎`
  Go to active search result
`+`
  Expand all sections
`-`
  Collapse all sections

## Search Tricks

Prefix searches with a type followed by a colon (e.g., `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g., `vec -> usize` or `* -> vec`)

Search multiple things at once by splitting your query with comma (e.g., `str,u8` or `String,struct:Vec,test`)