diff options
Diffstat (limited to 'third_party/rust/indexmap/src/map/core/raw_entry_v1.rs')
| -rw-r--r-- | third_party/rust/indexmap/src/map/core/raw_entry_v1.rs | 652 |
1 files changed, 652 insertions, 0 deletions
diff --git a/third_party/rust/indexmap/src/map/core/raw_entry_v1.rs b/third_party/rust/indexmap/src/map/core/raw_entry_v1.rs new file mode 100644 index 0000000000..87e532d557 --- /dev/null +++ b/third_party/rust/indexmap/src/map/core/raw_entry_v1.rs @@ -0,0 +1,652 @@ +//! Opt-in access to the experimental raw entry API. +//! +//! This module is designed to mimic the raw entry API of [`HashMap`][std::collections::hash_map], +//! matching its unstable state as of Rust 1.75. See the tracking issue +//! [rust#56167](https://github.com/rust-lang/rust/issues/56167) for more details. +//! +//! The trait [`RawEntryApiV1`] and the `_v1` suffix on its methods are meant to insulate this for +//! the future, in case later breaking changes are needed. If the standard library stabilizes its +//! `hash_raw_entry` feature (or some replacement), matching *inherent* methods will be added to +//! `IndexMap` without such an opt-in trait. + +use super::raw::RawTableEntry; +use super::IndexMapCore; +use crate::{Equivalent, HashValue, IndexMap}; +use core::fmt; +use core::hash::{BuildHasher, Hash, Hasher}; +use core::marker::PhantomData; +use core::mem; + +/// Opt-in access to the experimental raw entry API. +/// +/// See the [`raw_entry_v1`][self] module documentation for more information. +pub trait RawEntryApiV1<K, V, S>: private::Sealed { + /// Creates a raw immutable entry builder for the [`IndexMap`]. + /// + /// Raw entries provide the lowest level of control for searching and + /// manipulating a map. They must be manually initialized with a hash and + /// then manually searched. + /// + /// This is useful for + /// * Hash memoization + /// * Using a search key that doesn't work with the [`Equivalent`] trait + /// * Using custom comparison logic without newtype wrappers + /// + /// Unless you are in such a situation, higher-level and more foolproof APIs like + /// [`get`][IndexMap::get] should be preferred. + /// + /// Immutable raw entries have very limited use; you might instead want + /// [`raw_entry_mut_v1`][Self::raw_entry_mut_v1]. + /// + /// # Examples + /// + /// ``` + /// use core::hash::{BuildHasher, Hash}; + /// use indexmap::map::{IndexMap, RawEntryApiV1}; + /// + /// let mut map = IndexMap::new(); + /// map.extend([("a", 100), ("b", 200), ("c", 300)]); + /// + /// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 { + /// use core::hash::Hasher; + /// let mut state = hash_builder.build_hasher(); + /// key.hash(&mut state); + /// state.finish() + /// } + /// + /// for k in ["a", "b", "c", "d", "e", "f"] { + /// let hash = compute_hash(map.hasher(), k); + /// let i = map.get_index_of(k); + /// let v = map.get(k); + /// let kv = map.get_key_value(k); + /// let ikv = map.get_full(k); + /// + /// println!("Key: {} and value: {:?}", k, v); + /// + /// assert_eq!(map.raw_entry_v1().from_key(k), kv); + /// assert_eq!(map.raw_entry_v1().from_hash(hash, |q| *q == k), kv); + /// assert_eq!(map.raw_entry_v1().from_key_hashed_nocheck(hash, k), kv); + /// assert_eq!(map.raw_entry_v1().from_hash_full(hash, |q| *q == k), ikv); + /// assert_eq!(map.raw_entry_v1().index_from_hash(hash, |q| *q == k), i); + /// } + /// ``` + fn raw_entry_v1(&self) -> RawEntryBuilder<'_, K, V, S>; + + /// Creates a raw entry builder for the [`IndexMap`]. + /// + /// Raw entries provide the lowest level of control for searching and + /// manipulating a map. They must be manually initialized with a hash and + /// then manually searched. After this, insertions into a vacant entry + /// still require an owned key to be provided. + /// + /// Raw entries are useful for such exotic situations as: + /// + /// * Hash memoization + /// * Deferring the creation of an owned key until it is known to be required + /// * Using a search key that doesn't work with the [`Equivalent`] trait + /// * Using custom comparison logic without newtype wrappers + /// + /// Because raw entries provide much more low-level control, it's much easier + /// to put the `IndexMap` into an inconsistent state which, while memory-safe, + /// will cause the map to produce seemingly random results. Higher-level and more + /// foolproof APIs like [`entry`][IndexMap::entry] should be preferred when possible. + /// + /// Raw entries give mutable access to the keys. This must not be used + /// to modify how the key would compare or hash, as the map will not re-evaluate + /// where the key should go, meaning the keys may become "lost" if their + /// location does not reflect their state. For instance, if you change a key + /// so that the map now contains keys which compare equal, search may start + /// acting erratically, with two keys randomly masking each other. Implementations + /// are free to assume this doesn't happen (within the limits of memory-safety). + /// + /// # Examples + /// + /// ``` + /// use core::hash::{BuildHasher, Hash}; + /// use indexmap::map::{IndexMap, RawEntryApiV1}; + /// use indexmap::map::raw_entry_v1::RawEntryMut; + /// + /// let mut map = IndexMap::new(); + /// map.extend([("a", 100), ("b", 200), ("c", 300)]); + /// + /// fn compute_hash<K: Hash + ?Sized, S: BuildHasher>(hash_builder: &S, key: &K) -> u64 { + /// use core::hash::Hasher; + /// let mut state = hash_builder.build_hasher(); + /// key.hash(&mut state); + /// state.finish() + /// } + /// + /// // Existing key (insert and update) + /// match map.raw_entry_mut_v1().from_key("a") { + /// RawEntryMut::Vacant(_) => unreachable!(), + /// RawEntryMut::Occupied(mut view) => { + /// assert_eq!(view.index(), 0); + /// assert_eq!(view.get(), &100); + /// let v = view.get_mut(); + /// let new_v = (*v) * 10; + /// *v = new_v; + /// assert_eq!(view.insert(1111), 1000); + /// } + /// } + /// + /// assert_eq!(map["a"], 1111); + /// assert_eq!(map.len(), 3); + /// + /// // Existing key (take) + /// let hash = compute_hash(map.hasher(), "c"); + /// match map.raw_entry_mut_v1().from_key_hashed_nocheck(hash, "c") { + /// RawEntryMut::Vacant(_) => unreachable!(), + /// RawEntryMut::Occupied(view) => { + /// assert_eq!(view.index(), 2); + /// assert_eq!(view.shift_remove_entry(), ("c", 300)); + /// } + /// } + /// assert_eq!(map.raw_entry_v1().from_key("c"), None); + /// assert_eq!(map.len(), 2); + /// + /// // Nonexistent key (insert and update) + /// let key = "d"; + /// let hash = compute_hash(map.hasher(), key); + /// match map.raw_entry_mut_v1().from_hash(hash, |q| *q == key) { + /// RawEntryMut::Occupied(_) => unreachable!(), + /// RawEntryMut::Vacant(view) => { + /// assert_eq!(view.index(), 2); + /// let (k, value) = view.insert("d", 4000); + /// assert_eq!((*k, *value), ("d", 4000)); + /// *value = 40000; + /// } + /// } + /// assert_eq!(map["d"], 40000); + /// assert_eq!(map.len(), 3); + /// + /// match map.raw_entry_mut_v1().from_hash(hash, |q| *q == key) { + /// RawEntryMut::Vacant(_) => unreachable!(), + /// RawEntryMut::Occupied(view) => { + /// assert_eq!(view.index(), 2); + /// assert_eq!(view.swap_remove_entry(), ("d", 40000)); + /// } + /// } + /// assert_eq!(map.get("d"), None); + /// assert_eq!(map.len(), 2); + /// ``` + fn raw_entry_mut_v1(&mut self) -> RawEntryBuilderMut<'_, K, V, S>; +} + +impl<K, V, S> RawEntryApiV1<K, V, S> for IndexMap<K, V, S> { + fn raw_entry_v1(&self) -> RawEntryBuilder<'_, K, V, S> { + RawEntryBuilder { map: self } + } + + fn raw_entry_mut_v1(&mut self) -> RawEntryBuilderMut<'_, K, V, S> { + RawEntryBuilderMut { map: self } + } +} + +/// A builder for computing where in an [`IndexMap`] a key-value pair would be stored. +/// +/// This `struct` is created by the [`IndexMap::raw_entry_v1`] method, provided by the +/// [`RawEntryApiV1`] trait. See its documentation for more. +pub struct RawEntryBuilder<'a, K, V, S> { + map: &'a IndexMap<K, V, S>, +} + +impl<K, V, S> fmt::Debug for RawEntryBuilder<'_, K, V, S> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("RawEntryBuilder").finish_non_exhaustive() + } +} + +impl<'a, K, V, S> RawEntryBuilder<'a, K, V, S> { + /// Access an entry by key. + pub fn from_key<Q>(self, key: &Q) -> Option<(&'a K, &'a V)> + where + S: BuildHasher, + Q: ?Sized + Hash + Equivalent<K>, + { + self.map.get_key_value(key) + } + + /// Access an entry by a key and its hash. + pub fn from_key_hashed_nocheck<Q>(self, hash: u64, key: &Q) -> Option<(&'a K, &'a V)> + where + Q: ?Sized + Equivalent<K>, + { + let hash = HashValue(hash as usize); + let i = self.map.core.get_index_of(hash, key)?; + self.map.get_index(i) + } + + /// Access an entry by hash. + pub fn from_hash<F>(self, hash: u64, is_match: F) -> Option<(&'a K, &'a V)> + where + F: FnMut(&K) -> bool, + { + let map = self.map; + let i = self.index_from_hash(hash, is_match)?; + map.get_index(i) + } + + /// Access an entry by hash, including its index. + pub fn from_hash_full<F>(self, hash: u64, is_match: F) -> Option<(usize, &'a K, &'a V)> + where + F: FnMut(&K) -> bool, + { + let map = self.map; + let i = self.index_from_hash(hash, is_match)?; + let (key, value) = map.get_index(i)?; + Some((i, key, value)) + } + + /// Access the index of an entry by hash. + pub fn index_from_hash<F>(self, hash: u64, mut is_match: F) -> Option<usize> + where + F: FnMut(&K) -> bool, + { + let hash = HashValue(hash as usize); + let entries = &*self.map.core.entries; + let eq = move |&i: &usize| is_match(&entries[i].key); + self.map.core.indices.get(hash.get(), eq).copied() + } +} + +/// A builder for computing where in an [`IndexMap`] a key-value pair would be stored. +/// +/// This `struct` is created by the [`IndexMap::raw_entry_mut_v1`] method, provided by the +/// [`RawEntryApiV1`] trait. See its documentation for more. +pub struct RawEntryBuilderMut<'a, K, V, S> { + map: &'a mut IndexMap<K, V, S>, +} + +impl<K, V, S> fmt::Debug for RawEntryBuilderMut<'_, K, V, S> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("RawEntryBuilderMut").finish_non_exhaustive() + } +} + +impl<'a, K, V, S> RawEntryBuilderMut<'a, K, V, S> { + /// Access an entry by key. + pub fn from_key<Q>(self, key: &Q) -> RawEntryMut<'a, K, V, S> + where + S: BuildHasher, + Q: ?Sized + Hash + Equivalent<K>, + { + let hash = self.map.hash(key); + self.from_key_hashed_nocheck(hash.get(), key) + } + + /// Access an entry by a key and its hash. + pub fn from_key_hashed_nocheck<Q>(self, hash: u64, key: &Q) -> RawEntryMut<'a, K, V, S> + where + Q: ?Sized + Equivalent<K>, + { + self.from_hash(hash, |k| Q::equivalent(key, k)) + } + + /// Access an entry by hash. + pub fn from_hash<F>(self, hash: u64, is_match: F) -> RawEntryMut<'a, K, V, S> + where + F: FnMut(&K) -> bool, + { + let hash = HashValue(hash as usize); + match self.map.core.raw_entry(hash, is_match) { + Ok(raw) => RawEntryMut::Occupied(RawOccupiedEntryMut { + raw, + hash_builder: PhantomData, + }), + Err(map) => RawEntryMut::Vacant(RawVacantEntryMut { + map, + hash_builder: &self.map.hash_builder, + }), + } + } +} + +/// Raw entry for an existing key-value pair or a vacant location to +/// insert one. +pub enum RawEntryMut<'a, K, V, S> { + /// Existing slot with equivalent key. + Occupied(RawOccupiedEntryMut<'a, K, V, S>), + /// Vacant slot (no equivalent key in the map). + Vacant(RawVacantEntryMut<'a, K, V, S>), +} + +impl<K: fmt::Debug, V: fmt::Debug, S> fmt::Debug for RawEntryMut<'_, K, V, S> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + let mut tuple = f.debug_tuple("RawEntryMut"); + match self { + Self::Vacant(v) => tuple.field(v), + Self::Occupied(o) => tuple.field(o), + }; + tuple.finish() + } +} + +impl<'a, K, V, S> RawEntryMut<'a, K, V, S> { + /// Return the index where the key-value pair exists or may be inserted. + #[inline] + pub fn index(&self) -> usize { + match self { + Self::Occupied(entry) => entry.index(), + Self::Vacant(entry) => entry.index(), + } + } + + /// Inserts the given default key and value in the entry if it is vacant and returns mutable + /// references to them. Otherwise mutable references to an already existent pair are returned. + pub fn or_insert(self, default_key: K, default_value: V) -> (&'a mut K, &'a mut V) + where + K: Hash, + S: BuildHasher, + { + match self { + Self::Occupied(entry) => entry.into_key_value_mut(), + Self::Vacant(entry) => entry.insert(default_key, default_value), + } + } + + /// Inserts the result of the `call` function in the entry if it is vacant and returns mutable + /// references to them. Otherwise mutable references to an already existent pair are returned. + pub fn or_insert_with<F>(self, call: F) -> (&'a mut K, &'a mut V) + where + F: FnOnce() -> (K, V), + K: Hash, + S: BuildHasher, + { + match self { + Self::Occupied(entry) => entry.into_key_value_mut(), + Self::Vacant(entry) => { + let (key, value) = call(); + entry.insert(key, value) + } + } + } + + /// Modifies the entry if it is occupied. + pub fn and_modify<F>(mut self, f: F) -> Self + where + F: FnOnce(&mut K, &mut V), + { + if let Self::Occupied(entry) = &mut self { + let (k, v) = entry.get_key_value_mut(); + f(k, v); + } + self + } +} + +/// A raw view into an occupied entry in an [`IndexMap`]. +/// It is part of the [`RawEntryMut`] enum. +pub struct RawOccupiedEntryMut<'a, K, V, S> { + raw: RawTableEntry<'a, K, V>, + hash_builder: PhantomData<&'a S>, +} + +impl<K: fmt::Debug, V: fmt::Debug, S> fmt::Debug for RawOccupiedEntryMut<'_, K, V, S> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("RawOccupiedEntryMut") + .field("key", self.key()) + .field("value", self.get()) + .finish_non_exhaustive() + } +} + +impl<'a, K, V, S> RawOccupiedEntryMut<'a, K, V, S> { + /// Return the index of the key-value pair + #[inline] + pub fn index(&self) -> usize { + self.raw.index() + } + + /// Gets a reference to the entry's key in the map. + /// + /// Note that this is not the key that was used to find the entry. There may be an observable + /// difference if the key type has any distinguishing features outside of `Hash` and `Eq`, like + /// extra fields or the memory address of an allocation. + pub fn key(&self) -> &K { + &self.raw.bucket().key + } + + /// Gets a mutable reference to the entry's key in the map. + /// + /// Note that this is not the key that was used to find the entry. There may be an observable + /// difference if the key type has any distinguishing features outside of `Hash` and `Eq`, like + /// extra fields or the memory address of an allocation. + pub fn key_mut(&mut self) -> &mut K { + &mut self.raw.bucket_mut().key + } + + /// Converts into a mutable reference to the entry's key in the map, + /// with a lifetime bound to the map itself. + /// + /// Note that this is not the key that was used to find the entry. There may be an observable + /// difference if the key type has any distinguishing features outside of `Hash` and `Eq`, like + /// extra fields or the memory address of an allocation. + pub fn into_key(self) -> &'a mut K { + &mut self.raw.into_bucket().key + } + + /// Gets a reference to the entry's value in the map. + pub fn get(&self) -> &V { + &self.raw.bucket().value + } + + /// Gets a mutable reference to the entry's value in the map. + /// + /// If you need a reference which may outlive the destruction of the + /// [`RawEntryMut`] value, see [`into_mut`][Self::into_mut]. + pub fn get_mut(&mut self) -> &mut V { + &mut self.raw.bucket_mut().value + } + + /// Converts into a mutable reference to the entry's value in the map, + /// with a lifetime bound to the map itself. + pub fn into_mut(self) -> &'a mut V { + &mut self.raw.into_bucket().value + } + + /// Gets a reference to the entry's key and value in the map. + pub fn get_key_value(&self) -> (&K, &V) { + self.raw.bucket().refs() + } + + /// Gets a reference to the entry's key and value in the map. + pub fn get_key_value_mut(&mut self) -> (&mut K, &mut V) { + self.raw.bucket_mut().muts() + } + + /// Converts into a mutable reference to the entry's key and value in the map, + /// with a lifetime bound to the map itself. + pub fn into_key_value_mut(self) -> (&'a mut K, &'a mut V) { + self.raw.into_bucket().muts() + } + + /// Sets the value of the entry, and returns the entry's old value. + pub fn insert(&mut self, value: V) -> V { + mem::replace(self.get_mut(), value) + } + + /// Sets the key of the entry, and returns the entry's old key. + pub fn insert_key(&mut self, key: K) -> K { + mem::replace(self.key_mut(), key) + } + + /// Remove the key, value pair stored in the map for this entry, and return the value. + /// + /// **NOTE:** This is equivalent to [`.swap_remove()`][Self::swap_remove], replacing this + /// entry's position with the last element, and it is deprecated in favor of calling that + /// explicitly. If you need to preserve the relative order of the keys in the map, use + /// [`.shift_remove()`][Self::shift_remove] instead. + #[deprecated(note = "`remove` disrupts the map order -- \ + use `swap_remove` or `shift_remove` for explicit behavior.")] + pub fn remove(self) -> V { + self.swap_remove() + } + + /// Remove the key, value pair stored in the map for this entry, and return the value. + /// + /// Like [`Vec::swap_remove`][crate::Vec::swap_remove], the pair is removed by swapping it with + /// the last element of the map and popping it off. + /// **This perturbs the position of what used to be the last element!** + /// + /// Computes in **O(1)** time (average). + pub fn swap_remove(self) -> V { + self.swap_remove_entry().1 + } + + /// Remove the key, value pair stored in the map for this entry, and return the value. + /// + /// Like [`Vec::remove`][crate::Vec::remove], the pair is removed by shifting all of the + /// elements that follow it, preserving their relative order. + /// **This perturbs the index of all of those elements!** + /// + /// Computes in **O(n)** time (average). + pub fn shift_remove(self) -> V { + self.shift_remove_entry().1 + } + + /// Remove and return the key, value pair stored in the map for this entry + /// + /// **NOTE:** This is equivalent to [`.swap_remove_entry()`][Self::swap_remove_entry], + /// replacing this entry's position with the last element, and it is deprecated in favor of + /// calling that explicitly. If you need to preserve the relative order of the keys in the map, + /// use [`.shift_remove_entry()`][Self::shift_remove_entry] instead. + #[deprecated(note = "`remove_entry` disrupts the map order -- \ + use `swap_remove_entry` or `shift_remove_entry` for explicit behavior.")] + pub fn remove_entry(self) -> (K, V) { + self.swap_remove_entry() + } + + /// Remove and return the key, value pair stored in the map for this entry + /// + /// Like [`Vec::swap_remove`][crate::Vec::swap_remove], the pair is removed by swapping it with + /// the last element of the map and popping it off. + /// **This perturbs the position of what used to be the last element!** + /// + /// Computes in **O(1)** time (average). + pub fn swap_remove_entry(self) -> (K, V) { + let (map, index) = self.raw.remove_index(); + map.swap_remove_finish(index) + } + + /// Remove and return the key, value pair stored in the map for this entry + /// + /// Like [`Vec::remove`][crate::Vec::remove], the pair is removed by shifting all of the + /// elements that follow it, preserving their relative order. + /// **This perturbs the index of all of those elements!** + /// + /// Computes in **O(n)** time (average). + pub fn shift_remove_entry(self) -> (K, V) { + let (map, index) = self.raw.remove_index(); + map.shift_remove_finish(index) + } + + /// Moves the position of the entry to a new index + /// by shifting all other entries in-between. + /// + /// This is equivalent to [`IndexMap::move_index`] + /// coming `from` the current [`.index()`][Self::index]. + /// + /// * If `self.index() < to`, the other pairs will shift down while the targeted pair moves up. + /// * If `self.index() > to`, the other pairs will shift up while the targeted pair moves down. + /// + /// ***Panics*** if `to` is out of bounds. + /// + /// Computes in **O(n)** time (average). + pub fn move_index(self, to: usize) { + let (map, index) = self.raw.into_inner(); + map.move_index(index, to); + } + + /// Swaps the position of entry with another. + /// + /// This is equivalent to [`IndexMap::swap_indices`] + /// with the current [`.index()`][Self::index] as one of the two being swapped. + /// + /// ***Panics*** if the `other` index is out of bounds. + /// + /// Computes in **O(1)** time (average). + pub fn swap_indices(self, other: usize) { + let (map, index) = self.raw.into_inner(); + map.swap_indices(index, other) + } +} + +/// A view into a vacant raw entry in an [`IndexMap`]. +/// It is part of the [`RawEntryMut`] enum. +pub struct RawVacantEntryMut<'a, K, V, S> { + map: &'a mut IndexMapCore<K, V>, + hash_builder: &'a S, +} + +impl<K, V, S> fmt::Debug for RawVacantEntryMut<'_, K, V, S> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("RawVacantEntryMut").finish_non_exhaustive() + } +} + +impl<'a, K, V, S> RawVacantEntryMut<'a, K, V, S> { + /// Return the index where a key-value pair may be inserted. + pub fn index(&self) -> usize { + self.map.indices.len() + } + + /// Inserts the given key and value into the map, + /// and returns mutable references to them. + pub fn insert(self, key: K, value: V) -> (&'a mut K, &'a mut V) + where + K: Hash, + S: BuildHasher, + { + let mut h = self.hash_builder.build_hasher(); + key.hash(&mut h); + self.insert_hashed_nocheck(h.finish(), key, value) + } + + /// Inserts the given key and value into the map with the provided hash, + /// and returns mutable references to them. + pub fn insert_hashed_nocheck(self, hash: u64, key: K, value: V) -> (&'a mut K, &'a mut V) { + let hash = HashValue(hash as usize); + let i = self.map.insert_unique(hash, key, value); + self.map.entries[i].muts() + } + + /// Inserts the given key and value into the map at the given index, + /// shifting others to the right, and returns mutable references to them. + /// + /// ***Panics*** if `index` is out of bounds. + /// + /// Computes in **O(n)** time (average). + pub fn shift_insert(self, index: usize, key: K, value: V) -> (&'a mut K, &'a mut V) + where + K: Hash, + S: BuildHasher, + { + let mut h = self.hash_builder.build_hasher(); + key.hash(&mut h); + self.shift_insert_hashed_nocheck(index, h.finish(), key, value) + } + + /// Inserts the given key and value into the map with the provided hash + /// at the given index, and returns mutable references to them. + /// + /// ***Panics*** if `index` is out of bounds. + /// + /// Computes in **O(n)** time (average). + pub fn shift_insert_hashed_nocheck( + self, + index: usize, + hash: u64, + key: K, + value: V, + ) -> (&'a mut K, &'a mut V) { + let hash = HashValue(hash as usize); + self.map.shift_insert_unique(index, hash, key, value); + self.map.entries[index].muts() + } +} + +mod private { + pub trait Sealed {} + + impl<K, V, S> Sealed for super::IndexMap<K, V, S> {} +} |