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.
Vacant(VacantEntry<'a, K, V>)A vacant entry.
Occupied(OccupiedEntry<'a, K, V>)An occupied entry.
impl<'a, K, V> Entry<'a, K, V> where
K: Ord,
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fn or_insert(self, default: V) -> &'a mut V
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Ensures a value is in the entry by inserting the default if empty, and returns a mutable reference to the value in the entry.
use std::collections::BTreeMap;
let mut map: BTreeMap<&str, usize> = BTreeMap::new();
map.entry("poneyland").or_insert(12);
assert_eq!(map["poneyland"], 12); fn or_insert_with<F>(self, default: F) -> &'a mut V where
F: FnOnce() -> V,
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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.
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()); fn key(&self) -> &K
Returns a reference to this entry's key.
use std::collections::BTreeMap;
let mut map: BTreeMap<&str, usize> = BTreeMap::new();
assert_eq!(map.entry("poneyland").key(), &"poneyland"); fn and_modify<F>(self, f: F) -> Entry<'a, K, V> where
F: FnMut(&mut V) -> (),
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Provides in-place mutable access to an occupied entry before any potential inserts into the map.
#![feature(entry_and_modify)]
use std::collections::BTreeMap;
let mut map: BTreeMap<&str, usize> = BTreeMap::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); impl<'a, K, V> Entry<'a, K, V> where
K: Ord,
V: Default,
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fn or_default(self) -> &'a mut V
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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.
#![feature(entry_or_default)]
use std::collections::BTreeMap;
let mut map: BTreeMap<&str, Option<usize>> = BTreeMap::new();
map.entry("poneyland").or_default();
assert_eq!(map["poneyland"], None); impl<'a, K, V> Debug for Entry<'a, K, V> where
K: 'a + Ord + Debug,
V: 'a + Debug,
fn fmt(&self, f: &mut Formatter) -> Result<(), Error>
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Formats the value using the given formatter. Read more
© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/collections/btree_map/enum.Entry.html