314 lines
10 KiB
Rust
314 lines
10 KiB
Rust
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use crate::inner::{Core, OccupiedEntry, VacantEntry};
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use crate::Bucket;
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use core::{fmt, mem};
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/// Entry for an existing key-value pair in an [`IndexMap`][crate::IndexMap]
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/// or a vacant location to insert one.
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pub enum Entry<'a, K, V> {
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/// Existing slot with equivalent key.
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Occupied(OccupiedEntry<'a, K, V>),
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/// Vacant slot (no equivalent key in the map).
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Vacant(VacantEntry<'a, K, V>),
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}
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impl<'a, K, V> Entry<'a, K, V> {
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/// Return the index where the key-value pair exists or will be inserted.
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pub fn index(&self) -> usize {
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match self {
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Entry::Occupied(entry) => entry.index(),
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Entry::Vacant(entry) => entry.index(),
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}
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}
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/// Sets the value of the entry (after inserting if vacant), and returns an `OccupiedEntry`.
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///
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/// Computes in **O(1)** time (amortized average).
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pub fn insert_entry(self, value: V) -> OccupiedEntry<'a, K, V> {
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match self {
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Entry::Occupied(mut entry) => {
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entry.insert(value);
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entry
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}
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Entry::Vacant(entry) => entry.insert_entry(value),
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}
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}
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/// Inserts the given default value in the entry if it is vacant and returns a mutable
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/// reference to it. Otherwise a mutable reference to an already existent value is returned.
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///
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/// Computes in **O(1)** time (amortized average).
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pub fn or_insert(self, default: V) -> &'a mut V {
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match self {
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Entry::Occupied(entry) => entry.into_mut(),
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Entry::Vacant(entry) => entry.insert(default),
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}
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}
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/// Inserts the result of the `call` function in the entry if it is vacant and returns a mutable
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/// reference to it. Otherwise a mutable reference to an already existent value is returned.
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///
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/// Computes in **O(1)** time (amortized average).
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pub fn or_insert_with<F>(self, call: F) -> &'a mut V
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where
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F: FnOnce() -> V,
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{
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match self {
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Entry::Occupied(entry) => entry.into_mut(),
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Entry::Vacant(entry) => entry.insert(call()),
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}
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}
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/// Inserts the result of the `call` function with a reference to the entry's key if it is
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/// vacant, and returns a mutable reference to the new value. Otherwise a mutable reference to
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/// an already existent value is returned.
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///
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/// Computes in **O(1)** time (amortized average).
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pub fn or_insert_with_key<F>(self, call: F) -> &'a mut V
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where
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F: FnOnce(&K) -> V,
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{
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match self {
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Entry::Occupied(entry) => entry.into_mut(),
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Entry::Vacant(entry) => {
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let value = call(entry.key());
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entry.insert(value)
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}
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}
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}
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/// Gets a reference to the entry's key, either within the map if occupied,
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/// or else the new key that was used to find the entry.
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pub fn key(&self) -> &K {
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match *self {
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Entry::Occupied(ref entry) => entry.key(),
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Entry::Vacant(ref entry) => entry.key(),
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}
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}
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/// Modifies the entry if it is occupied.
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pub fn and_modify<F>(mut self, f: F) -> Self
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where
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F: FnOnce(&mut V),
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{
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if let Entry::Occupied(entry) = &mut self {
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f(entry.get_mut());
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}
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self
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}
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/// Inserts a default-constructed value in the entry if it is vacant and returns a mutable
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/// reference to it. Otherwise a mutable reference to an already existent value is returned.
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///
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/// Computes in **O(1)** time (amortized average).
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pub fn or_default(self) -> &'a mut V
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where
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V: Default,
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{
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match self {
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Entry::Occupied(entry) => entry.into_mut(),
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Entry::Vacant(entry) => entry.insert(V::default()),
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}
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}
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}
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impl<K: fmt::Debug, V: fmt::Debug> fmt::Debug for Entry<'_, K, V> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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let mut tuple = f.debug_tuple("Entry");
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match self {
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Entry::Vacant(v) => tuple.field(v),
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Entry::Occupied(o) => tuple.field(o),
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};
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tuple.finish()
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}
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}
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impl<K: fmt::Debug, V: fmt::Debug> fmt::Debug for OccupiedEntry<'_, K, V> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.debug_struct("OccupiedEntry")
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.field("key", self.key())
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.field("value", self.get())
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.finish()
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}
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}
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impl<K: fmt::Debug, V> fmt::Debug for VacantEntry<'_, K, V> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.debug_tuple("VacantEntry").field(self.key()).finish()
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}
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}
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/// A view into an occupied entry in an [`IndexMap`][crate::IndexMap] obtained by index.
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///
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/// This `struct` is created from the [`get_index_entry`][crate::IndexMap::get_index_entry] method.
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pub struct IndexedEntry<'a, K, V> {
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map: &'a mut Core<K, V>,
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// We have a mutable reference to the map, which keeps the index
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// valid and pointing to the correct entry.
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index: usize,
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}
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impl<'a, K, V> IndexedEntry<'a, K, V> {
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pub(crate) fn new(map: &'a mut Core<K, V>, index: usize) -> Option<Self> {
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if index < map.len() {
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Some(Self { map, index })
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} else {
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None
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}
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}
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/// Return the index of the key-value pair
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#[inline]
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pub fn index(&self) -> usize {
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self.index
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}
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pub(crate) fn into_core(self) -> &'a mut Core<K, V> {
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self.map
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}
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fn get_bucket(&self) -> &Bucket<K, V> {
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&self.map.as_entries()[self.index]
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}
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fn get_bucket_mut(&mut self) -> &mut Bucket<K, V> {
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&mut self.map.as_entries_mut()[self.index]
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}
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fn into_bucket(self) -> &'a mut Bucket<K, V> {
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&mut self.map.as_entries_mut()[self.index]
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}
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/// Gets a reference to the entry's key in the map.
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pub fn key(&self) -> &K {
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&self.get_bucket().key
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}
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pub(super) fn key_mut(&mut self) -> &mut K {
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&mut self.get_bucket_mut().key
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}
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/// Gets a reference to the entry's value in the map.
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pub fn get(&self) -> &V {
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&self.get_bucket().value
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}
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/// Gets a mutable reference to the entry's value in the map.
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///
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/// If you need a reference which may outlive the destruction of the
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/// `IndexedEntry` value, see [`into_mut`][Self::into_mut].
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pub fn get_mut(&mut self) -> &mut V {
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&mut self.get_bucket_mut().value
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}
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/// Sets the value of the entry to `value`, and returns the entry's old value.
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pub fn insert(&mut self, value: V) -> V {
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mem::replace(self.get_mut(), value)
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}
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/// Converts into a mutable reference to the entry's value in the map,
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/// with a lifetime bound to the map itself.
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pub fn into_mut(self) -> &'a mut V {
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&mut self.into_bucket().value
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}
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/// Remove and return the key, value pair stored in the map for this entry
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///
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/// Like [`Vec::swap_remove`][alloc::vec::Vec::swap_remove], the pair is removed by swapping it
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/// with the last element of the map and popping it off.
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/// **This perturbs the position of what used to be the last element!**
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///
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/// Computes in **O(1)** time (average).
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pub fn swap_remove_entry(self) -> (K, V) {
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self.map.swap_remove_index(self.index).unwrap()
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}
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/// Remove and return the key, value pair stored in the map for this entry
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///
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/// Like [`Vec::remove`][alloc::vec::Vec::remove], the pair is removed by shifting all of the
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/// elements that follow it, preserving their relative order.
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/// **This perturbs the index of all of those elements!**
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///
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/// Computes in **O(n)** time (average).
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pub fn shift_remove_entry(self) -> (K, V) {
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self.map.shift_remove_index(self.index).unwrap()
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}
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/// Remove the key, value pair stored in the map for this entry, and return the value.
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///
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/// Like [`Vec::swap_remove`][alloc::vec::Vec::swap_remove], the pair is removed by swapping it
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/// with the last element of the map and popping it off.
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/// **This perturbs the position of what used to be the last element!**
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///
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/// Computes in **O(1)** time (average).
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pub fn swap_remove(self) -> V {
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self.swap_remove_entry().1
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}
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/// Remove the key, value pair stored in the map for this entry, and return the value.
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///
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/// Like [`Vec::remove`][alloc::vec::Vec::remove], the pair is removed by shifting all of the
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/// elements that follow it, preserving their relative order.
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/// **This perturbs the index of all of those elements!**
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///
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/// Computes in **O(n)** time (average).
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pub fn shift_remove(self) -> V {
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self.shift_remove_entry().1
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}
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/// Moves the position of the entry to a new index
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/// by shifting all other entries in-between.
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///
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/// This is equivalent to [`IndexMap::move_index`][`crate::IndexMap::move_index`]
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/// coming `from` the current [`.index()`][Self::index].
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///
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/// * If `self.index() < to`, the other pairs will shift down while the targeted pair moves up.
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/// * If `self.index() > to`, the other pairs will shift up while the targeted pair moves down.
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///
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/// ***Panics*** if `to` is out of bounds.
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///
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/// Computes in **O(n)** time (average).
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#[track_caller]
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pub fn move_index(self, to: usize) {
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self.map.move_index(self.index, to);
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}
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/// Swaps the position of entry with another.
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///
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/// This is equivalent to [`IndexMap::swap_indices`][`crate::IndexMap::swap_indices`]
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/// with the current [`.index()`][Self::index] as one of the two being swapped.
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///
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/// ***Panics*** if the `other` index is out of bounds.
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///
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/// Computes in **O(1)** time (average).
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#[track_caller]
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pub fn swap_indices(self, other: usize) {
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self.map.swap_indices(self.index, other);
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}
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}
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impl<K: fmt::Debug, V: fmt::Debug> fmt::Debug for IndexedEntry<'_, K, V> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.debug_struct("IndexedEntry")
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.field("index", &self.index)
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.field("key", self.key())
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.field("value", self.get())
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.finish()
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}
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}
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impl<'a, K, V> From<OccupiedEntry<'a, K, V>> for IndexedEntry<'a, K, V> {
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fn from(other: OccupiedEntry<'a, K, V>) -> Self {
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Self {
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index: other.index(),
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map: other.into_core(),
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}
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}
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}
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#[test]
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fn assert_send_sync() {
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fn assert_send_sync<T: Send + Sync>() {}
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assert_send_sync::<Entry<'_, i32, i32>>();
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assert_send_sync::<IndexedEntry<'_, i32, i32>>();
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}
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