diff options
Diffstat (limited to 'library/alloc/src/collections/btree/map/entry.rs')
-rw-r--r-- | library/alloc/src/collections/btree/map/entry.rs | 555 |
1 files changed, 555 insertions, 0 deletions
diff --git a/library/alloc/src/collections/btree/map/entry.rs b/library/alloc/src/collections/btree/map/entry.rs new file mode 100644 index 000000000..b6eecf9b0 --- /dev/null +++ b/library/alloc/src/collections/btree/map/entry.rs @@ -0,0 +1,555 @@ +use core::fmt::{self, Debug}; +use core::marker::PhantomData; +use core::mem; + +use crate::alloc::{Allocator, Global}; + +use super::super::borrow::DormantMutRef; +use super::super::node::{marker, Handle, NodeRef}; +use super::BTreeMap; + +use Entry::*; + +/// 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`]. +/// +/// [`entry`]: BTreeMap::entry +#[stable(feature = "rust1", since = "1.0.0")] +#[cfg_attr(not(test), rustc_diagnostic_item = "BTreeEntry")] +pub enum Entry< + 'a, + K: 'a, + V: 'a, + #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator + Clone = Global, +> { + /// A vacant entry. + #[stable(feature = "rust1", since = "1.0.0")] + Vacant(#[stable(feature = "rust1", since = "1.0.0")] VacantEntry<'a, K, V, A>), + + /// An occupied entry. + #[stable(feature = "rust1", since = "1.0.0")] + Occupied(#[stable(feature = "rust1", since = "1.0.0")] OccupiedEntry<'a, K, V, A>), +} + +#[stable(feature = "debug_btree_map", since = "1.12.0")] +impl<K: Debug + Ord, V: Debug, A: Allocator + Clone> Debug for Entry<'_, K, V, A> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match *self { + Vacant(ref v) => f.debug_tuple("Entry").field(v).finish(), + Occupied(ref o) => f.debug_tuple("Entry").field(o).finish(), + } + } +} + +/// A view into a vacant entry in a `BTreeMap`. +/// It is part of the [`Entry`] enum. +#[stable(feature = "rust1", since = "1.0.0")] +pub struct VacantEntry< + 'a, + K, + V, + #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator + Clone = Global, +> { + pub(super) key: K, + /// `None` for a (empty) map without root + pub(super) handle: Option<Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, marker::Edge>>, + pub(super) dormant_map: DormantMutRef<'a, BTreeMap<K, V, A>>, + + /// The BTreeMap will outlive this IntoIter so we don't care about drop order for `alloc`. + pub(super) alloc: A, + + // Be invariant in `K` and `V` + pub(super) _marker: PhantomData<&'a mut (K, V)>, +} + +#[stable(feature = "debug_btree_map", since = "1.12.0")] +impl<K: Debug + Ord, V, A: Allocator + Clone> Debug for VacantEntry<'_, K, V, A> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_tuple("VacantEntry").field(self.key()).finish() + } +} + +/// A view into an occupied entry in a `BTreeMap`. +/// It is part of the [`Entry`] enum. +#[stable(feature = "rust1", since = "1.0.0")] +pub struct OccupiedEntry< + 'a, + K, + V, + #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator + Clone = Global, +> { + pub(super) handle: Handle<NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInternal>, marker::KV>, + pub(super) dormant_map: DormantMutRef<'a, BTreeMap<K, V, A>>, + + /// The BTreeMap will outlive this IntoIter so we don't care about drop order for `alloc`. + pub(super) alloc: A, + + // Be invariant in `K` and `V` + pub(super) _marker: PhantomData<&'a mut (K, V)>, +} + +#[stable(feature = "debug_btree_map", since = "1.12.0")] +impl<K: Debug + Ord, V: Debug, A: Allocator + Clone> Debug for OccupiedEntry<'_, K, V, A> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("OccupiedEntry").field("key", self.key()).field("value", self.get()).finish() + } +} + +/// The error returned by [`try_insert`](BTreeMap::try_insert) when the key already exists. +/// +/// Contains the occupied entry, and the value that was not inserted. +#[unstable(feature = "map_try_insert", issue = "82766")] +pub struct OccupiedError<'a, K: 'a, V: 'a, A: Allocator + Clone = Global> { + /// The entry in the map that was already occupied. + pub entry: OccupiedEntry<'a, K, V, A>, + /// The value which was not inserted, because the entry was already occupied. + pub value: V, +} + +#[unstable(feature = "map_try_insert", issue = "82766")] +impl<K: Debug + Ord, V: Debug, A: Allocator + Clone> Debug for OccupiedError<'_, K, V, A> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("OccupiedError") + .field("key", self.entry.key()) + .field("old_value", self.entry.get()) + .field("new_value", &self.value) + .finish() + } +} + +#[unstable(feature = "map_try_insert", issue = "82766")] +impl<'a, K: Debug + Ord, V: Debug, A: Allocator + Clone> fmt::Display + for OccupiedError<'a, K, V, A> +{ + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + write!( + f, + "failed to insert {:?}, key {:?} already exists with value {:?}", + self.value, + self.entry.key(), + self.entry.get(), + ) + } +} + +impl<'a, K: Ord, V, A: Allocator + Clone> Entry<'a, K, V, A> { + /// Ensures a value is in the entry by inserting the default if empty, and returns + /// a mutable reference to the value in the entry. + /// + /// # Examples + /// + /// ``` + /// use std::collections::BTreeMap; + /// + /// let mut map: BTreeMap<&str, usize> = BTreeMap::new(); + /// map.entry("poneyland").or_insert(12); + /// + /// assert_eq!(map["poneyland"], 12); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn or_insert(self, default: V) -> &'a mut V { + match self { + Occupied(entry) => entry.into_mut(), + Vacant(entry) => entry.insert(default), + } + } + + /// 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. + /// + /// # Examples + /// + /// ``` + /// 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()); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn or_insert_with<F: FnOnce() -> V>(self, default: F) -> &'a mut V { + match self { + Occupied(entry) => entry.into_mut(), + Vacant(entry) => entry.insert(default()), + } + } + + /// Ensures a value is in the entry by inserting, if empty, the result of the default function. + /// This method allows for generating key-derived values for insertion by providing the default + /// function a reference to the key that was moved during the `.entry(key)` method call. + /// + /// The reference to the moved key is provided so that cloning or copying the key is + /// unnecessary, unlike with `.or_insert_with(|| ... )`. + /// + /// # Examples + /// + /// ``` + /// use std::collections::BTreeMap; + /// + /// let mut map: BTreeMap<&str, usize> = BTreeMap::new(); + /// + /// map.entry("poneyland").or_insert_with_key(|key| key.chars().count()); + /// + /// assert_eq!(map["poneyland"], 9); + /// ``` + #[inline] + #[stable(feature = "or_insert_with_key", since = "1.50.0")] + pub fn or_insert_with_key<F: FnOnce(&K) -> V>(self, default: F) -> &'a mut V { + match self { + Occupied(entry) => entry.into_mut(), + Vacant(entry) => { + let value = default(entry.key()); + entry.insert(value) + } + } + } + + /// Returns a reference to this entry's key. + /// + /// # Examples + /// + /// ``` + /// use std::collections::BTreeMap; + /// + /// let mut map: BTreeMap<&str, usize> = BTreeMap::new(); + /// assert_eq!(map.entry("poneyland").key(), &"poneyland"); + /// ``` + #[stable(feature = "map_entry_keys", since = "1.10.0")] + pub fn key(&self) -> &K { + match *self { + Occupied(ref entry) => entry.key(), + Vacant(ref entry) => entry.key(), + } + } + + /// Provides in-place mutable access to an occupied entry before any + /// potential inserts into the map. + /// + /// # Examples + /// + /// ``` + /// 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); + /// ``` + #[stable(feature = "entry_and_modify", since = "1.26.0")] + pub fn and_modify<F>(self, f: F) -> Self + where + F: FnOnce(&mut V), + { + match self { + Occupied(mut entry) => { + f(entry.get_mut()); + Occupied(entry) + } + Vacant(entry) => Vacant(entry), + } + } +} + +impl<'a, K: Ord, V: Default, A: Allocator + Clone> Entry<'a, K, V, A> { + #[stable(feature = "entry_or_default", since = "1.28.0")] + /// 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. + /// + /// # Examples + /// + /// ``` + /// use std::collections::BTreeMap; + /// + /// let mut map: BTreeMap<&str, Option<usize>> = BTreeMap::new(); + /// map.entry("poneyland").or_default(); + /// + /// assert_eq!(map["poneyland"], None); + /// ``` + pub fn or_default(self) -> &'a mut V { + match self { + Occupied(entry) => entry.into_mut(), + Vacant(entry) => entry.insert(Default::default()), + } + } +} + +impl<'a, K: Ord, V, A: Allocator + Clone> VacantEntry<'a, K, V, A> { + /// Gets a reference to the key that would be used when inserting a value + /// through the VacantEntry. + /// + /// # Examples + /// + /// ``` + /// use std::collections::BTreeMap; + /// + /// let mut map: BTreeMap<&str, usize> = BTreeMap::new(); + /// assert_eq!(map.entry("poneyland").key(), &"poneyland"); + /// ``` + #[stable(feature = "map_entry_keys", since = "1.10.0")] + pub fn key(&self) -> &K { + &self.key + } + + /// Take ownership of the key. + /// + /// # Examples + /// + /// ``` + /// use std::collections::BTreeMap; + /// use std::collections::btree_map::Entry; + /// + /// let mut map: BTreeMap<&str, usize> = BTreeMap::new(); + /// + /// if let Entry::Vacant(v) = map.entry("poneyland") { + /// v.into_key(); + /// } + /// ``` + #[stable(feature = "map_entry_recover_keys2", since = "1.12.0")] + pub fn into_key(self) -> K { + self.key + } + + /// Sets the value of the entry with the `VacantEntry`'s key, + /// and returns a mutable reference to it. + /// + /// # Examples + /// + /// ``` + /// use std::collections::BTreeMap; + /// use std::collections::btree_map::Entry; + /// + /// let mut map: BTreeMap<&str, u32> = BTreeMap::new(); + /// + /// if let Entry::Vacant(o) = map.entry("poneyland") { + /// o.insert(37); + /// } + /// assert_eq!(map["poneyland"], 37); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn insert(self, value: V) -> &'a mut V { + let out_ptr = match self.handle { + None => { + // SAFETY: There is no tree yet so no reference to it exists. + let map = unsafe { self.dormant_map.awaken() }; + let mut root = NodeRef::new_leaf(self.alloc.clone()); + let val_ptr = root.borrow_mut().push(self.key, value) as *mut V; + map.root = Some(root.forget_type()); + map.length = 1; + val_ptr + } + Some(handle) => match handle.insert_recursing(self.key, value, self.alloc.clone()) { + (None, val_ptr) => { + // SAFETY: We have consumed self.handle. + let map = unsafe { self.dormant_map.awaken() }; + map.length += 1; + val_ptr + } + (Some(ins), val_ptr) => { + drop(ins.left); + // SAFETY: We have consumed self.handle and dropped the + // remaining reference to the tree, ins.left. + let map = unsafe { self.dormant_map.awaken() }; + let root = map.root.as_mut().unwrap(); // same as ins.left + root.push_internal_level(self.alloc).push(ins.kv.0, ins.kv.1, ins.right); + map.length += 1; + val_ptr + } + }, + }; + // Now that we have finished growing the tree using borrowed references, + // dereference the pointer to a part of it, that we picked up along the way. + unsafe { &mut *out_ptr } + } +} + +impl<'a, K: Ord, V, A: Allocator + Clone> OccupiedEntry<'a, K, V, A> { + /// Gets a reference to the key in the entry. + /// + /// # Examples + /// + /// ``` + /// use std::collections::BTreeMap; + /// + /// let mut map: BTreeMap<&str, usize> = BTreeMap::new(); + /// map.entry("poneyland").or_insert(12); + /// assert_eq!(map.entry("poneyland").key(), &"poneyland"); + /// ``` + #[must_use] + #[stable(feature = "map_entry_keys", since = "1.10.0")] + pub fn key(&self) -> &K { + self.handle.reborrow().into_kv().0 + } + + /// Take ownership of the key and value from the map. + /// + /// # Examples + /// + /// ``` + /// use std::collections::BTreeMap; + /// use std::collections::btree_map::Entry; + /// + /// let mut map: BTreeMap<&str, usize> = BTreeMap::new(); + /// map.entry("poneyland").or_insert(12); + /// + /// if let Entry::Occupied(o) = map.entry("poneyland") { + /// // We delete the entry from the map. + /// o.remove_entry(); + /// } + /// + /// // If now try to get the value, it will panic: + /// // println!("{}", map["poneyland"]); + /// ``` + #[stable(feature = "map_entry_recover_keys2", since = "1.12.0")] + pub fn remove_entry(self) -> (K, V) { + self.remove_kv() + } + + /// Gets a reference to the value in the entry. + /// + /// # Examples + /// + /// ``` + /// use std::collections::BTreeMap; + /// use std::collections::btree_map::Entry; + /// + /// let mut map: BTreeMap<&str, usize> = BTreeMap::new(); + /// map.entry("poneyland").or_insert(12); + /// + /// if let Entry::Occupied(o) = map.entry("poneyland") { + /// assert_eq!(o.get(), &12); + /// } + /// ``` + #[must_use] + #[stable(feature = "rust1", since = "1.0.0")] + pub fn get(&self) -> &V { + self.handle.reborrow().into_kv().1 + } + + /// Gets a mutable reference to the value in the entry. + /// + /// If you need a reference to the `OccupiedEntry` that may outlive the + /// destruction of the `Entry` value, see [`into_mut`]. + /// + /// [`into_mut`]: OccupiedEntry::into_mut + /// + /// # Examples + /// + /// ``` + /// use std::collections::BTreeMap; + /// use std::collections::btree_map::Entry; + /// + /// let mut map: BTreeMap<&str, usize> = BTreeMap::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); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn get_mut(&mut self) -> &mut V { + self.handle.kv_mut().1 + } + + /// Converts the entry into a mutable reference to its value. + /// + /// If you need multiple references to the `OccupiedEntry`, see [`get_mut`]. + /// + /// [`get_mut`]: OccupiedEntry::get_mut + /// + /// # Examples + /// + /// ``` + /// use std::collections::BTreeMap; + /// use std::collections::btree_map::Entry; + /// + /// let mut map: BTreeMap<&str, usize> = BTreeMap::new(); + /// map.entry("poneyland").or_insert(12); + /// + /// assert_eq!(map["poneyland"], 12); + /// if let Entry::Occupied(o) = map.entry("poneyland") { + /// *o.into_mut() += 10; + /// } + /// assert_eq!(map["poneyland"], 22); + /// ``` + #[must_use = "`self` will be dropped if the result is not used"] + #[stable(feature = "rust1", since = "1.0.0")] + pub fn into_mut(self) -> &'a mut V { + self.handle.into_val_mut() + } + + /// Sets the value of the entry with the `OccupiedEntry`'s key, + /// and returns the entry's old value. + /// + /// # Examples + /// + /// ``` + /// use std::collections::BTreeMap; + /// use std::collections::btree_map::Entry; + /// + /// let mut map: BTreeMap<&str, usize> = BTreeMap::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); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn insert(&mut self, value: V) -> V { + mem::replace(self.get_mut(), value) + } + + /// Takes the value of the entry out of the map, and returns it. + /// + /// # Examples + /// + /// ``` + /// use std::collections::BTreeMap; + /// use std::collections::btree_map::Entry; + /// + /// let mut map: BTreeMap<&str, usize> = BTreeMap::new(); + /// map.entry("poneyland").or_insert(12); + /// + /// if let Entry::Occupied(o) = map.entry("poneyland") { + /// assert_eq!(o.remove(), 12); + /// } + /// // If we try to get "poneyland"'s value, it'll panic: + /// // println!("{}", map["poneyland"]); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn remove(self) -> V { + self.remove_kv().1 + } + + // Body of `remove_entry`, probably separate because the name reflects the returned pair. + pub(super) fn remove_kv(self) -> (K, V) { + let mut emptied_internal_root = false; + let (old_kv, _) = + self.handle.remove_kv_tracking(|| emptied_internal_root = true, self.alloc.clone()); + // SAFETY: we consumed the intermediate root borrow, `self.handle`. + let map = unsafe { self.dormant_map.awaken() }; + map.length -= 1; + if emptied_internal_root { + let root = map.root.as_mut().unwrap(); + root.pop_internal_level(self.alloc); + } + old_kv + } +} |