std::collections::hash_map::OccupiedEntry - Rust
Description: API documentation for the Rust `OccupiedEntry` struct in crate `std`.
Keywords: rust, rustlang, rust-lang, OccupiedEntry

# 1.0.0[−][src]Struct std::collections::hash_map::OccupiedEntry

    pub struct OccupiedEntry<'a, K: 'a, V: 'a> { /* fields omitted */ }

A view into an occupied entry in a `HashMap`. It is part of the `Entry` enum.

## Implementations

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

#### `pub fn key(&self) -> &Kⓘ

### Notable traits for &'_ mut I

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

Gets a reference to the key in the entry.

# Examples

    use std::collections::HashMap;

    let mut map: HashMap<&str, u32> = HashMap::new();
    map.entry("poneyland").or_insert(12);
    assert_eq!(map.entry("poneyland").key(), &"poneyland");

Run

#### `pub fn remove_entry(self) -> (K, V)`1.12.0[src]

Take the ownership of the key and value from the map.

# Examples

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

    let mut map: HashMap<&str, u32> = HashMap::new();
    map.entry("poneyland").or_insert(12);

    if let Entry::Occupied(o) = map.entry("poneyland") {
        // We delete the entry from the map.
        o.remove_entry();
    }

    assert_eq!(map.contains_key("poneyland"), false);

Run

#### `pub fn get(&self) -> &Vⓘ

### Notable traits for &'_ mut I

`impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<R: Read + ?Sized, '_> Read for &'_ mut Rimpl<W: Write + ?Sized, '_> Write for &'_ mut W`
`[src]

Gets a reference to the value in the entry.

# Examples

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

    let mut map: HashMap<&str, u32> = HashMap::new();
    map.entry("poneyland").or_insert(12);

    if let Entry::Occupied(o) = map.entry("poneyland") {
        assert_eq!(o.get(), &12);
    }

Run

#### `pub fn get_mut(&mut self) -> &mut Vⓘ

### Notable traits for &'_ mut I

`impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<R: Read + ?Sized, '_> Read for &'_ mut Rimpl<W: Write + ?Sized, '_> Write for &'_ mut W`
`[src]

Gets a mutable reference to the value in the entry.

If you need a reference to the `OccupiedEntry` which may outlive the destruction of the `Entry` value, see `into_mut`.

# Examples

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

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

        // We can use the same Entry multiple times.
        *o.get_mut() += 2;
    }

    assert_eq!(map["poneyland"], 24);

Run

#### `pub fn into_mut(self) -> &'a mut Vⓘ

### Notable traits for &'_ mut I

`impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<R: Read + ?Sized, '_> Read for &'_ mut Rimpl<W: Write + ?Sized, '_> Write for &'_ mut W`
`[src]

Converts the OccupiedEntry into a mutable reference to the value in the entry with a lifetime bound to the map itself.

If you need multiple references to the `OccupiedEntry`, see `get_mut`.

# Examples

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

    let mut map: HashMap<&str, u32> = HashMap::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

#### `pub fn insert(&mut self, value: V) -> V`[src]

Sets the value of the entry, and returns the entry's old value.

# Examples

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

    let mut map: HashMap<&str, u32> = HashMap::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

#### `pub fn remove(self) -> V`[src]

Takes the value out of the entry, and returns it.

# Examples

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

    let mut map: HashMap<&str, u32> = HashMap::new();
    map.entry("poneyland").or_insert(12);

    if let Entry::Occupied(o) = map.entry("poneyland") {
        assert_eq!(o.remove(), 12);
    }

    assert_eq!(map.contains_key("poneyland"), false);

Run

#### `pub fn replace_entry(self, value: V) -> (K, V)`[src]

🔬 This is a nightly-only experimental API. (`map_entry_replace` #44286)

Replaces the entry, returning the old key and value. The new key in the hash map will be the key used to create this entry.

# Examples

    #![feature(map_entry_replace)]
    use std::collections::hash_map::{Entry, HashMap};
    use std::rc::Rc;

    let mut map: HashMap<Rc<String>, u32> = HashMap::new();
    map.insert(Rc::new("Stringthing".to_string()), 15);

    let my_key = Rc::new("Stringthing".to_string());

    if let Entry::Occupied(entry) = map.entry(my_key) {
        // Also replace the key with a handle to our other key.
        let (old_key, old_value): (Rc<String>, u32) = entry.replace_entry(16);
    }

Run

#### `pub fn replace_key(self) -> K`[src]

🔬 This is a nightly-only experimental API. (`map_entry_replace` #44286)

Replaces the key in the hash map with the key used to create this entry.

# Examples

    #![feature(map_entry_replace)]
    use std::collections::hash_map::{Entry, HashMap};
    use std::rc::Rc;

    let mut map: HashMap<Rc<String>, u32> = HashMap::new();
    let mut known_strings: Vec<Rc<String>> = Vec::new();

    // Initialise known strings, run program, etc.

    reclaim_memory(&mut map, &known_strings);

    fn reclaim_memory(map: &mut HashMap<Rc<String>, u32>, known_strings: &[Rc<String>] ) {
        for s in known_strings {
            if let Entry::Occupied(entry) = map.entry(s.clone()) {
                // Replaces the entry's key with our version of it in `known_strings`.
                entry.replace_key();
            }
        }
    }

Run

## Trait Implementations

### `impl<K: Debug, V: Debug, '_> Debug for OccupiedEntry<'_, 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> RefUnwindSafe for OccupiedEntry<'a, K, V> where
K: RefUnwindSafe,
V: RefUnwindSafe,`

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

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

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

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

## Blanket Implementations

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

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

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

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

#### `fn borrow(&self) -> &Tⓘ

### Notable traits for &'_ mut I

`impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<R: Read + ?Sized, '_> Read for &'_ mut Rimpl<W: Write + ?Sized, '_> Write for &'_ mut W`
`[src]

Immutably borrows from an owned value. Read more

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

#### `fn borrow_mut(&mut self) -> &mut Tⓘ

### Notable traits for &'_ mut I

`impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<R: Read + ?Sized, '_> Read for &'_ mut Rimpl<W: Write + ?Sized, '_> Write for &'_ mut W`
`[src]

Mutably borrows from an owned value. Read more

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

#### `fn from(t: T) -> T`[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, 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> 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.