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135 lines
3.6 KiB
135 lines
3.6 KiB
//! Map entries.
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//!
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//! The API is similar to that of `BTreeMap` and `HashMap`'s `Entry` types.
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use super::*;
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/// Varient of [`Entry`](Entry) that already contains a value.
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#[derive(Debug)]
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pub struct OccupiedEntry<'a, K, V>(pub(crate) &'a mut Option<(K,V)>);
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impl<'a, K, V> OccupiedEntry<'a, K, V>
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where K: Collapse
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{
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/// Get a reference to the value
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pub fn get(&self) -> &V
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{
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&self.0.as_ref().unwrap().1
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}
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/// Get a mutable reference to the value
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pub fn get_mut(&mut self) -> &mut V
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{
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&mut self.0.as_mut().unwrap().1
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}
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/// Consume this instance, returning the held mutable reference to the value
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pub fn into_mut(self) -> &'a mut V
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{
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&mut self.0.as_mut().unwrap().1
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}
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/// A reference to the key
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pub fn key(&self) -> &K
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{
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&self.0.as_ref().unwrap().0
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}
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/// Replace the held value with another, yielding the old one
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pub fn insert(&mut self, value: V) -> V
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{
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core::mem::replace(&mut self.0.as_mut().unwrap().1, value)
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}
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/// Remove this entry from the `Map`, yielding the removed value
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pub fn remove(self) -> V
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{
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self.remove_entry().1
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}
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/// Remove this entry from the `Map`, yielding the removed key-value pair.
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pub fn remove_entry(self) -> (K, V)
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{
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self.0.take().unwrap()
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}
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}
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/// Varient of [`Entry`](Entry) that does not contain a value.
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#[derive(Debug)]
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pub struct VacantEntry<'a,K,V>(pub(crate) &'a mut Option<(K,V)>, pub(crate) K);
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impl<'a, K, V> VacantEntry<'a, K, V>
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where K: Collapse
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{
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/// Insert a value into this empty slot, retuning a mutable reference to the new value.
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pub fn insert(self, value: V) -> &'a mut V
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{
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*self.0 = Some((self.1, value));
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&mut self.0.as_mut().unwrap().1
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}
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/// Consume this instance, returning the held key.
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pub fn into_key(self) -> K
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{
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self.1
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}
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/// A reference to the held key
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pub fn key(&self) -> &K
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{
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&self.1
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}
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}
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/// Represents a space in a `Map` that may or may not contains a value.
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#[derive(Debug)]
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pub enum Entry<'a, K, V>
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{
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/// This entry slot does not yet contain a value
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Vacant(VacantEntry<'a, K, V>),
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/// This entry slot does contain a value
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Occupied(OccupiedEntry<'a, K, V>),
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}
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impl<'a, K, V> Entry<'a, K, V>
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where K: Collapse
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{
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/// Run this closure on a mutable reference to the internal value if it is present, otherwise do nothing.
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pub fn and_modify<F: FnOnce(&mut V)>(mut self, f: F) -> Entry<'a, K, V>
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{
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if let Self::Occupied(occuped) = &mut self {
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f(occuped.get_mut())
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}
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self
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}
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/// A reference to the key
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pub fn key(&self) -> &K
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{
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match self {
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Entry::Vacant(v) => v.key(),
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Entry::Occupied(o) => o.key(),
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}
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}
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/// Insert into the entry if it is empty the value returned by the closure and return a mutable reference to the new value, otherwise return a mutable reference to the already present value.
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pub fn or_insert_with<F: FnOnce() -> V>(self, with: F) -> &'a mut V
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{
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match self {
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Entry::Occupied(o) => o.into_mut(),
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Entry::Vacant(v) => v.insert(with())
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}
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}
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/// Insert into the entry this value if it is empty and return a mutable reference to the new value, otherwise return a mutable reference to the already present value.
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#[inline] pub fn or_insert(self, value: V) -> &'a mut V
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{
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self.or_insert_with(|| value)
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}
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}
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impl<'a, K, V> Entry<'a, K, V>
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where K: Collapse,
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V: Default
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{
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/// Insert into the entry the default value if it is empty and return a mutable reference to the new value, otherwise return a mutable reference to the already present value.
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#[inline] pub fn or_default(self) -> &'a mut V
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{
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self.or_insert_with(Default::default)
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}
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}
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