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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::*;
/// map 中单个条目的视图,该条目可能是空的或被已占用。
///
/// `enum` 是根据 [`BTreeMap`] 上的 [`entry`] 方法构造的。
///
/// [`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,
> {
/// 一个空的条目。
#[stable(feature = "rust1", since = "1.0.0")]
Vacant(#[stable(feature = "rust1", since = "1.0.0")] VacantEntry<'a, K, V, A>),
/// 一个被占用的条目。
#[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(),
}
}
}
/// `BTreeMap` 中空条目的视图。
/// 它是 [`Entry`] 枚举的一部分。
#[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` 用于没有 root 的 (empty) map
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>>,
/// BTreeMap 将比 IntoIter 活得长,所以我们不关心 `alloc` 的丢弃顺序。
pub(super) alloc: A,
// 在 `K` 和 `V` 中保持不变
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()
}
}
/// `BTreeMap` 中已占用条目的视图。
/// 它是 [`Entry`] 枚举的一部分。
#[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>>,
/// BTreeMap 将比 IntoIter 活得长,所以我们不关心 `alloc` 的丢弃顺序。
pub(super) alloc: A,
// 在 `K` 和 `V` 中保持不变
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()
}
}
/// 当键已经存在时,由 [`try_insert`](BTreeMap::try_insert) 返回的错误。
///
/// 包含占用的条目和未插入的值。
#[unstable(feature = "map_try_insert", issue = "82766")]
pub struct OccupiedError<'a, K: 'a, V: 'a, A: Allocator + Clone = Global> {
/// map 中已被占用的条目。
pub entry: OccupiedEntry<'a, K, V, A>,
/// 未插入的值,因为该条目已被占用。
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(),
)
}
}
#[unstable(feature = "map_try_insert", issue = "82766")]
impl<'a, K: core::fmt::Debug + Ord, V: core::fmt::Debug> core::error::Error
for crate::collections::btree_map::OccupiedError<'a, K, V>
{
#[allow(deprecated)]
fn description(&self) -> &str {
"key already exists"
}
}
impl<'a, K: Ord, V, A: Allocator + Clone> Entry<'a, K, V, A> {
/// 如果为空,则通过插入默认值来确保该值在条目中,并返回对条目中值的可变引用。
///
///
/// # 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),
}
}
/// 如果为空,则通过插入默认函数的结果来确保该值在条目中,并返回对条目中值的可变引用。
///
///
/// # 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()),
}
}
/// 如果为空,则通过插入默认函数的结果,确保值在条目中。
/// 通过为 `.entry(key)` 方法调用期间移动的键提供默认函数引用,此方法可以生成用于插入的键派生值。
///
///
/// 提供了对已移动键的引用,因此不需要克隆或复制键,这与 `.or_insert_with(|| ... )` 不同。
///
/// # 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)
}
}
}
/// 返回此条目的键的引用。
///
/// # 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(),
}
}
/// 在任何潜在的插入 map 之前,提供对占用条目的就地可变访问。
///
///
/// # 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")]
/// 如果为空,则通过插入默认值来确保值在条目中,并向条目中的值返回变量引用。
///
///
/// # 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> {
/// 获取对通过 VacantEntry 插入值时将使用的键的引用。
///
///
/// # 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
}
/// 取得键的所有权。
///
/// # 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
}
/// 用 `VacantEntry` 的键设置条目的值,并返回对它的可变引用。
///
///
/// # 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(mut self, value: V) -> &'a mut V {
let out_ptr = match self.handle {
None => {
// SAFETY: 还没有树,所以不存在对它的引用。
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) => {
let new_handle =
handle.insert_recursing(self.key, value, self.alloc.clone(), |ins| {
drop(ins.left);
// SAFETY: 推送新的根节点不会使现有节点的句柄无效。
//
let map = unsafe { self.dormant_map.reborrow() };
let root = map.root.as_mut().unwrap(); // 与 ins.left 相同
root.push_internal_level(self.alloc).push(ins.kv.0, ins.kv.1, ins.right)
});
// 获取指向值的指针
let val_ptr = new_handle.into_val_mut();
// SAFETY: 我们已经消耗了 self.handle。
let map = unsafe { self.dormant_map.awaken() };
map.length += 1;
val_ptr
}
};
// 现在我们已经完成了使用借来的引用完成了树的生长,解除对它的一部分的指针的引用,这是我们在开发过程中得到的。
//
unsafe { &mut *out_ptr }
}
}
impl<'a, K: Ord, V, A: Allocator + Clone> OccupiedEntry<'a, K, V, A> {
/// 获取条目中键的引用。
///
/// # 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
}
/// 从 map 获取键和值的所有权。
///
/// # 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") {
/// // 我们从 map 中删除了这个条目。
/// o.remove_entry();
/// }
///
/// // 如果现在尝试获取该值,它将为 panic:
/// // println!("{}", map["poneyland"]);
/// ```
#[stable(feature = "map_entry_recover_keys2", since = "1.12.0")]
pub fn remove_entry(self) -> (K, V) {
self.remove_kv()
}
/// 获取条目中值的引用。
///
/// # 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
}
/// 获取条目中的值的可变引用。
///
/// 如果您需要引用可能比销毁 `Entry` 值还长的 `OccupiedEntry`,请参阅 [`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);
///
/// // 我们可以多次使用同一个 Entry。
/// *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
}
/// 将条目转换为其值的可变引用。
///
/// 如果需要多次引用 `OccupiedEntry`,请参见 [`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()
}
/// 使用 `OccupiedEntry` 键设置条目的值,并返回条目的旧值。
///
///
/// # 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)
}
/// 从 map 中获取条目的值,并将其返回。
///
/// # 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);
/// }
/// // 如果我们尝试获得 `poneyland` 的值,则它将为 panic:
/// // println!("{}", map["poneyland"]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn remove(self) -> V {
self.remove_kv().1
}
// `remove_entry` 的主体,可能是分开的,因为名称反映了返回的对。
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: 我们消耗了中间根借用,`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
}
}