Struct hashbrown::hash_map::OccupiedEntry
source · pub struct OccupiedEntry<'a, K, V, S = DefaultHashBuilder, A: Allocator = Global> { /* private fields */ }
Expand description
A view into an occupied entry in a HashMap
.
It is part of the Entry
and EntryRef
enums.
§Examples
use hashbrown::hash_map::{Entry, HashMap, OccupiedEntry};
let mut map = HashMap::new();
map.extend([("a", 10), ("b", 20), ("c", 30)]);
let _entry_o: OccupiedEntry<_, _, _> = map.entry("a").insert(100);
assert_eq!(map.len(), 3);
// Existing key (insert and update)
match map.entry("a") {
Entry::Vacant(_) => unreachable!(),
Entry::Occupied(mut view) => {
assert_eq!(view.get(), &100);
let v = view.get_mut();
*v *= 10;
assert_eq!(view.insert(1111), 1000);
}
}
assert_eq!(map[&"a"], 1111);
assert_eq!(map.len(), 3);
// Existing key (take)
match map.entry("c") {
Entry::Vacant(_) => unreachable!(),
Entry::Occupied(view) => {
assert_eq!(view.remove_entry(), ("c", 30));
}
}
assert_eq!(map.get(&"c"), None);
assert_eq!(map.len(), 2);
Implementations§
source§impl<'a, K, V, S, A: Allocator> OccupiedEntry<'a, K, V, S, A>
impl<'a, K, V, S, A: Allocator> OccupiedEntry<'a, K, V, S, A>
sourcepub fn key(&self) -> &K
pub fn key(&self) -> &K
Gets a reference to the key in the entry.
§Examples
use hashbrown::hash_map::{Entry, HashMap};
let mut map: HashMap<&str, u32> = HashMap::new();
map.entry("poneyland").or_insert(12);
match map.entry("poneyland") {
Entry::Vacant(_) => panic!(),
Entry::Occupied(entry) => assert_eq!(entry.key(), &"poneyland"),
}
sourcepub fn remove_entry(self) -> (K, V)
pub fn remove_entry(self) -> (K, V)
Take the ownership of the key and value from the map. Keeps the allocated memory for reuse.
§Examples
use hashbrown::HashMap;
use hashbrown::hash_map::Entry;
let mut map: HashMap<&str, u32> = HashMap::new();
// The map is empty
assert!(map.is_empty() && map.capacity() == 0);
map.entry("poneyland").or_insert(12);
if let Entry::Occupied(o) = map.entry("poneyland") {
// We delete the entry from the map.
assert_eq!(o.remove_entry(), ("poneyland", 12));
}
assert_eq!(map.contains_key("poneyland"), false);
// Now map hold none elements
assert!(map.is_empty());
sourcepub fn get(&self) -> &V
pub fn get(&self) -> &V
Gets a reference to the value in the entry.
§Examples
use hashbrown::HashMap;
use hashbrown::hash_map::Entry;
let mut map: HashMap<&str, u32> = HashMap::new();
map.entry("poneyland").or_insert(12);
match map.entry("poneyland") {
Entry::Vacant(_) => panic!(),
Entry::Occupied(entry) => assert_eq!(entry.get(), &12),
}
sourcepub fn get_mut(&mut self) -> &mut V
pub fn get_mut(&mut self) -> &mut V
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 hashbrown::HashMap;
use hashbrown::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);
sourcepub fn into_mut(self) -> &'a mut V
pub fn into_mut(self) -> &'a mut V
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 hashbrown::hash_map::{Entry, HashMap};
let mut map: HashMap<&str, u32> = HashMap::new();
map.entry("poneyland").or_insert(12);
assert_eq!(map["poneyland"], 12);
let value: &mut u32;
match map.entry("poneyland") {
Entry::Occupied(entry) => value = entry.into_mut(),
Entry::Vacant(_) => panic!(),
}
*value += 10;
assert_eq!(map["poneyland"], 22);
sourcepub fn insert(&mut self, value: V) -> V
pub fn insert(&mut self, value: V) -> V
Sets the value of the entry, and returns the entry’s old value.
§Examples
use hashbrown::HashMap;
use hashbrown::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);
sourcepub fn remove(self) -> V
pub fn remove(self) -> V
Takes the value out of the entry, and returns it. Keeps the allocated memory for reuse.
§Examples
use hashbrown::HashMap;
use hashbrown::hash_map::Entry;
let mut map: HashMap<&str, u32> = HashMap::new();
// The map is empty
assert!(map.is_empty() && map.capacity() == 0);
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);
// Now map hold none elements
assert!(map.is_empty());
sourcepub fn replace_entry_with<F>(self, f: F) -> Entry<'a, K, V, S, A>
pub fn replace_entry_with<F>(self, f: F) -> Entry<'a, K, V, S, A>
Provides shared access to the key and owned access to the value of the entry and allows to replace or remove it based on the value of the returned option.
§Examples
use hashbrown::HashMap;
use hashbrown::hash_map::Entry;
let mut map: HashMap<&str, u32> = HashMap::new();
map.insert("poneyland", 42);
let entry = match map.entry("poneyland") {
Entry::Occupied(e) => {
e.replace_entry_with(|k, v| {
assert_eq!(k, &"poneyland");
assert_eq!(v, 42);
Some(v + 1)
})
}
Entry::Vacant(_) => panic!(),
};
match entry {
Entry::Occupied(e) => {
assert_eq!(e.key(), &"poneyland");
assert_eq!(e.get(), &43);
}
Entry::Vacant(_) => panic!(),
}
assert_eq!(map["poneyland"], 43);
let entry = match map.entry("poneyland") {
Entry::Occupied(e) => e.replace_entry_with(|_k, _v| None),
Entry::Vacant(_) => panic!(),
};
match entry {
Entry::Vacant(e) => {
assert_eq!(e.key(), &"poneyland");
}
Entry::Occupied(_) => panic!(),
}
assert!(!map.contains_key("poneyland"));