From 4b96049da2329ba6e9a7fd4cd8224417fb4baede Mon Sep 17 00:00:00 2001 From: Jacob Hughes Date: Mon, 12 Oct 2020 08:44:53 -0400 Subject: [PATCH] BTreeMap: refactor Entry out of map.rs into its own file btree/map.rs is approaching the 3000 line mark, splitting out the entry code buys about 500 lines of headroom --- library/alloc/src/collections/btree/map.rs | 473 +---------------- .../alloc/src/collections/btree/map/entry.rs | 475 ++++++++++++++++++ 2 files changed, 480 insertions(+), 468 deletions(-) create mode 100644 library/alloc/src/collections/btree/map/entry.rs diff --git a/library/alloc/src/collections/btree/map.rs b/library/alloc/src/collections/btree/map.rs index 606bf94f99867..92cbce96054b8 100644 --- a/library/alloc/src/collections/btree/map.rs +++ b/library/alloc/src/collections/btree/map.rs @@ -9,13 +9,16 @@ use core::ops::{Index, RangeBounds}; use core::ptr; use super::borrow::DormantMutRef; -use super::node::{self, marker, ForceResult::*, Handle, InsertResult::*, NodeRef}; +use super::node::{self, marker, ForceResult::*, Handle, NodeRef}; use super::search::{self, SearchResult::*}; use super::unwrap_unchecked; -use Entry::*; use UnderflowResult::*; +mod entry; +pub use entry::{Entry, OccupiedEntry, VacantEntry}; +use Entry::*; + /// A map based on a B-Tree. /// /// B-Trees represent a fundamental compromise between cache-efficiency and actually minimizing @@ -452,69 +455,6 @@ impl fmt::Debug for RangeMut<'_, 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`]. -/// -/// [`entry`]: BTreeMap::entry -#[stable(feature = "rust1", since = "1.0.0")] -pub enum Entry<'a, K: 'a, V: 'a> { - /// A vacant entry. - #[stable(feature = "rust1", since = "1.0.0")] - Vacant(#[stable(feature = "rust1", since = "1.0.0")] VacantEntry<'a, K, V>), - - /// An occupied entry. - #[stable(feature = "rust1", since = "1.0.0")] - Occupied(#[stable(feature = "rust1", since = "1.0.0")] OccupiedEntry<'a, K, V>), -} - -#[stable(feature = "debug_btree_map", since = "1.12.0")] -impl Debug for Entry<'_, K, V> { - 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: 'a, V: 'a> { - key: K, - handle: Handle, K, V, marker::Leaf>, marker::Edge>, - dormant_map: DormantMutRef<'a, BTreeMap>, - - // Be invariant in `K` and `V` - _marker: PhantomData<&'a mut (K, V)>, -} - -#[stable(feature = "debug_btree_map", since = "1.12.0")] -impl Debug for VacantEntry<'_, K, V> { - 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: 'a, V: 'a> { - handle: Handle, K, V, marker::LeafOrInternal>, marker::KV>, - dormant_map: DormantMutRef<'a, BTreeMap>, - - // Be invariant in `K` and `V` - _marker: PhantomData<&'a mut (K, V)>, -} - -#[stable(feature = "debug_btree_map", since = "1.12.0")] -impl Debug for OccupiedEntry<'_, K, V> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - f.debug_struct("OccupiedEntry").field("key", self.key()).field("value", self.get()).finish() - } -} - // An iterator for merging two sorted sequences into one struct MergeIter> { left: Peekable, @@ -2310,409 +2250,6 @@ impl BTreeMap { } } -impl<'a, K: Ord, V> Entry<'a, K, V> { - /// 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 V>(self, default: F) -> &'a mut V { - match self { - Occupied(entry) => entry.into_mut(), - Vacant(entry) => entry.insert(default()), - } - } - - #[unstable(feature = "or_insert_with_key", issue = "71024")] - /// Ensures a value is in the entry by inserting, if empty, the result of the default function, - /// which takes the key as its argument, and returns a mutable reference to the value in the - /// entry. - /// - /// # Examples - /// - /// ``` - /// #![feature(or_insert_with_key)] - /// 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] - pub fn or_insert_with_key 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(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> Entry<'a, K, V> { - #[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> = 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> VacantEntry<'a, K, V> { - /// 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.insert_recursing(self.key, value) { - (Fit(_), val_ptr) => { - // Safety: We have consumed self.handle and the handle returned. - let map = unsafe { self.dormant_map.awaken() }; - map.length += 1; - val_ptr - } - (Split(ins), val_ptr) => { - drop(ins.left); - // Safety: We have consumed self.handle and the reference returned. - let map = unsafe { self.dormant_map.awaken() }; - let root = map.root.as_mut().unwrap(); - root.push_internal_level().push(ins.k, ins.v, 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> OccupiedEntry<'a, K, V> { - /// 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"); - /// ``` - #[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); - /// } - /// ``` - #[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); - /// ``` - #[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`, separate to keep the above implementations short. - fn remove_kv(self) -> (K, V) { - let mut emptied_internal_root = false; - let (old_kv, _) = self.handle.remove_kv_tracking(|| emptied_internal_root = true); - // 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(); - } - old_kv - } -} - impl<'a, K: 'a, V: 'a> Handle, K, V, marker::LeafOrInternal>, marker::KV> { /// Removes a key/value-pair from the map, and returns that pair, as well as /// the leaf edge corresponding to that former pair. 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 0000000000000..73a0ca21f6733 --- /dev/null +++ b/library/alloc/src/collections/btree/map/entry.rs @@ -0,0 +1,475 @@ +use core::fmt::{self, Debug}; +use core::marker::PhantomData; +use core::mem; + +use super::super::borrow::DormantMutRef; +use super::super::node::{marker, Handle, InsertResult::*, 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")] +pub enum Entry<'a, K: 'a, V: 'a> { + /// A vacant entry. + #[stable(feature = "rust1", since = "1.0.0")] + Vacant(#[stable(feature = "rust1", since = "1.0.0")] VacantEntry<'a, K, V>), + + /// An occupied entry. + #[stable(feature = "rust1", since = "1.0.0")] + Occupied(#[stable(feature = "rust1", since = "1.0.0")] OccupiedEntry<'a, K, V>), +} + +#[stable(feature = "debug_btree_map", since = "1.12.0")] +impl Debug for Entry<'_, K, V> { + 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: 'a, V: 'a> { + pub(super) key: K, + pub(super) handle: Handle, K, V, marker::Leaf>, marker::Edge>, + pub(super) dormant_map: DormantMutRef<'a, BTreeMap>, + + // Be invariant in `K` and `V` + pub(super) _marker: PhantomData<&'a mut (K, V)>, +} + +#[stable(feature = "debug_btree_map", since = "1.12.0")] +impl Debug for VacantEntry<'_, K, V> { + 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: 'a, V: 'a> { + pub(super) handle: Handle, K, V, marker::LeafOrInternal>, marker::KV>, + pub(super) dormant_map: DormantMutRef<'a, BTreeMap>, + + // Be invariant in `K` and `V` + pub(super) _marker: PhantomData<&'a mut (K, V)>, +} + +#[stable(feature = "debug_btree_map", since = "1.12.0")] +impl Debug for OccupiedEntry<'_, K, V> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("OccupiedEntry").field("key", self.key()).field("value", self.get()).finish() + } +} + +impl<'a, K: Ord, V> Entry<'a, K, V> { + /// 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 V>(self, default: F) -> &'a mut V { + match self { + Occupied(entry) => entry.into_mut(), + Vacant(entry) => entry.insert(default()), + } + } + + #[unstable(feature = "or_insert_with_key", issue = "71024")] + /// Ensures a value is in the entry by inserting, if empty, the result of the default function, + /// which takes the key as its argument, and returns a mutable reference to the value in the + /// entry. + /// + /// # Examples + /// + /// ``` + /// #![feature(or_insert_with_key)] + /// 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] + pub fn or_insert_with_key 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(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> Entry<'a, K, V> { + #[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> = 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> VacantEntry<'a, K, V> { + /// 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.insert_recursing(self.key, value) { + (Fit(_), val_ptr) => { + // Safety: We have consumed self.handle and the handle returned. + let map = unsafe { self.dormant_map.awaken() }; + map.length += 1; + val_ptr + } + (Split(ins), val_ptr) => { + drop(ins.left); + // Safety: We have consumed self.handle and the reference returned. + let map = unsafe { self.dormant_map.awaken() }; + let root = map.root.as_mut().unwrap(); + root.push_internal_level().push(ins.k, ins.v, 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> OccupiedEntry<'a, K, V> { + /// 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"); + /// ``` + #[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); + /// } + /// ``` + #[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); + /// ``` + #[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`, separate to keep the above implementations short. + 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); + // 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(); + } + old_kv + } +}