std::collections::btree_map::Entry - Rust
Description: API documentation for the Rust `Entry` enum in crate `std`.
Keywords: rust, rustlang, rust-lang, Entry

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

    pub enum Entry<'a, K, V> where
        K: 'a,
        V: 'a,  {
        Vacant(VacantEntry<'a, K, V>),
        Occupied(OccupiedEntry<'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 `BTreeMap`.

## Variants

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

A vacant entry.

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

An occupied entry.

## Methods

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

#### `fn or_insert(self, default: V) -> &'a mut V`

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::BTreeMap;

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

    assert_eq!(map["poneyland"], 12);Run

#### `fn or_insert_with<F>(self, default: F) -> &'a mut V where
F: FnOnce() -> V,`

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::BTreeMap;

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

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

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

#### `fn key(&self) -> &K`
1.10.0

Returns a reference to this entry's key.

# Examples

    use std::collections::BTreeMap;

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

## Trait Implementations

### `impl<'a, K, V> Debug for Entry<'a, K, V> where
K: 'a + Ord + Debug,
V: 'a + Debug,`
1.12.0
[src]

#### `fn fmt(&self, f: &mut Formatter) -> Result<(), Error>`

Formats the value using the given formatter.

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