pub enum Entry<'a, T>where
T: 'a,{
Occupied(OccupiedEntry<'a, T>),
Vacant(VacantEntry<'a, T>),
}
Expand description
A view into a single location in a HeaderMap
, which may be vacant or occupied.
Variants§
Implementations§
Source§impl<'a, T> Entry<'a, T>
impl<'a, T> Entry<'a, T>
Sourcepub fn or_insert(self, default: T) -> &'a mut T
pub fn or_insert(self, default: T) -> &'a mut T
Ensures a value is in the entry by inserting the default if empty.
Returns a mutable reference to the first value in the entry.
§Panics
This method panics if capacity exceeds max HeaderMap
capacity
§Examples
let mut map: HeaderMap<u32> = HeaderMap::default();
let headers = &[
"content-length",
"x-hello",
"Content-Length",
"x-world",
];
for &header in headers {
let counter = map.entry(header)
.or_insert(0);
*counter += 1;
}
assert_eq!(map["content-length"], 2);
assert_eq!(map["x-hello"], 1);
Sourcepub fn or_try_insert(self, default: T) -> Result<&'a mut T, MaxSizeReached>
pub fn or_try_insert(self, default: T) -> Result<&'a mut T, MaxSizeReached>
Ensures a value is in the entry by inserting the default if empty.
Returns a mutable reference to the first value in the entry.
§Errors
This function may return an error if HeaderMap
exceeds max capacity
§Examples
let mut map: HeaderMap<u32> = HeaderMap::default();
let headers = &[
"content-length",
"x-hello",
"Content-Length",
"x-world",
];
for &header in headers {
let counter = map.entry(header)
.or_try_insert(0)
.unwrap();
*counter += 1;
}
assert_eq!(map["content-length"], 2);
assert_eq!(map["x-hello"], 1);
Sourcepub fn or_insert_with<F>(self, default: F) -> &'a mut Twhere
F: FnOnce() -> T,
pub fn or_insert_with<F>(self, default: F) -> &'a mut Twhere
F: FnOnce() -> T,
Ensures a value is in the entry by inserting the result of the default function if empty.
The default function is not called if the entry exists in the map. Returns a mutable reference to the first value in the entry.
§Examples
Basic usage.
let mut map = HeaderMap::new();
let res = map.entry("x-hello")
.or_insert_with(|| "world".parse().unwrap());
assert_eq!(res, "world");
The default function is not called if the entry exists in the map.
let mut map = HeaderMap::new();
map.try_insert(HOST, "world".parse().unwrap()).unwrap();
let res = map.try_entry("host")
.unwrap()
.or_try_insert_with(|| unreachable!())
.unwrap();
assert_eq!(res, "world");
Sourcepub fn or_try_insert_with<F>(
self,
default: F,
) -> Result<&'a mut T, MaxSizeReached>where
F: FnOnce() -> T,
pub fn or_try_insert_with<F>(
self,
default: F,
) -> Result<&'a mut T, MaxSizeReached>where
F: FnOnce() -> T,
Ensures a value is in the entry by inserting the result of the default function if empty.
The default function is not called if the entry exists in the map. Returns a mutable reference to the first value in the entry.
§Examples
Basic usage.
let mut map = HeaderMap::new();
let res = map.entry("x-hello")
.or_insert_with(|| "world".parse().unwrap());
assert_eq!(res, "world");
The default function is not called if the entry exists in the map.
let mut map = HeaderMap::new();
map.try_insert(HOST, "world".parse().unwrap()).unwrap();
let res = map.try_entry("host")
.unwrap()
.or_try_insert_with(|| unreachable!())
.unwrap();
assert_eq!(res, "world");
Sourcepub fn key(&self) -> &HeaderName
pub fn key(&self) -> &HeaderName
Returns a reference to the entry’s key
§Examples
let mut map = HeaderMap::new();
assert_eq!(map.entry("x-hello").key(), "x-hello");
Trait Implementations§
Auto Trait Implementations§
impl<'a, T> !Freeze for Entry<'a, T>
impl<'a, T> RefUnwindSafe for Entry<'a, T>where
T: RefUnwindSafe,
impl<'a, T> Send for Entry<'a, T>where
T: Send,
impl<'a, T> Sync for Entry<'a, T>where
T: Sync,
impl<'a, T> Unpin for Entry<'a, T>
impl<'a, T> !UnwindSafe for Entry<'a, T>
Blanket Implementations§
Source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
Source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Layout§
Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...)
attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.
Size: 56 bytes
Size for each variant:
Occupied
: 24 bytesVacant
: 56 bytes