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

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

    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.

## Methods

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

####
ⓘImportant traits for &'a mut I

### Important traits for &'a mut I

`impl<'a, I> Iterator for &'a mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'a, R: Read + ?Sized> Read for &'a mut Rimpl<'a, W: Write + ?Sized> Write for &'a mut W`
`pub fn key(&self) -> &K`
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

####
ⓘImportant traits for &'a mut I

### Important traits for &'a mut I

`impl<'a, I> Iterator for &'a mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'a, R: Read + ?Sized> Read for &'a mut Rimpl<'a, W: Write + ?Sized> Write for &'a mut W`
`pub fn get(&self) -> &V`
[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

####
ⓘImportant traits for &'a mut I

### Important traits for &'a mut I

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

Gets a mutable 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);

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

    assert_eq!(map["poneyland"], 22);Run

####
ⓘImportant traits for &'a mut I

### Important traits for &'a mut I

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

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

# 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<'a, K: 'a + Debug, V: 'a + Debug> Debug for OccupiedEntry<'a, K, V>`
1.12.0
[src]

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

Formats the value using the given formatter. Read more

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