Enum Entry

pub enum Entry<'a>

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 Map.

Variants

Vacant(VacantEntry<'a>)

A vacant Entry.

Occupied(OccupiedEntry<'a>)

An occupied Entry.

Implementations

impl<'a> Entry<'a>

fn key(&self) -> &String

Returns a reference to this entry's key.

Examples

let mut map = serde_json::Map::new();
assert_eq!(map.entry("serde").key(), &"serde");
fn or_insert(self, default: Value) -> &'a mut Value

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 serde_json::json;
#
let mut map = serde_json::Map::new();
map.entry("serde").or_insert(json!(12));

assert_eq!(map["serde"], 12);
fn or_insert_with<F>(self, default: F) -> &'a mut Value
where
    F: FnOnce() -> Value,

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 serde_json::json;
#
let mut map = serde_json::Map::new();
map.entry("serde").or_insert_with(|| json!("hoho"));

assert_eq!(map["serde"], "hoho".to_owned());
fn and_modify<F>(self, f: F) -> Self
where
    F: FnOnce(&mut Value),

Provides in-place mutable access to an occupied entry before any potential inserts into the map.

Examples

# use serde_json::json;
#
let mut map = serde_json::Map::new();
map.entry("serde")
    .and_modify(|e| *e = json!("rust"))
    .or_insert(json!("cpp"));

assert_eq!(map["serde"], "cpp");

map.entry("serde")
    .and_modify(|e| *e = json!("rust"))
    .or_insert(json!("cpp"));

assert_eq!(map["serde"], "rust");

Auto Trait Implementations

impl<'a> !UnwindSafe for Entry<'a>

impl<'a> Freeze for Entry<'a>

impl<'a> RefUnwindSafe for Entry<'a>

impl<'a> Send for Entry<'a>

impl<'a> Sync for Entry<'a>

impl<'a> Unpin for Entry<'a>

impl<'a> UnsafeUnpin for Entry<'a>

Blanket Implementations

impl<T> Any for Entry<'a> where T: 'static + ?Sized,

fn type_id(&self) -> TypeId

impl<T> Borrow<T> for Entry<'a> where T: ?Sized,

fn borrow(&self) -> &T

impl<T> BorrowMut<T> for Entry<'a> where T: ?Sized,

fn borrow_mut(&mut self) -> &mut T

impl<T> From<T> for Entry<'a>

fn from(t: T) -> T

Returns the argument unchanged.

impl<T, U> Into<U> for Entry<'a> where U: From<T>,

fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of [From]<T> for U chooses to do.

impl<T, U> TryFrom<U> for Entry<'a> where U: Into<T>,

type Error = never;
fn try_from(value: U) -> Result<T, never>

impl<T, U> TryInto<U> for Entry<'a> where U: TryFrom<T>,

type Error = <U as TryFrom<T>>::Error;
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>