Enum tower_grpc::metadata::Entry

pub enum Entry<'a, VE: ValueEncoding> {
    Occupied(OccupiedEntry<'a, VE>),
    Vacant(VacantEntry<'a, VE>),
}

A view into a single location in a MetadataMap, which may be vacant or occupied.

Variants

Occupied(OccupiedEntry<'a, VE>)

An occupied entry

Vacant(VacantEntry<'a, VE>)

A vacant entry

Methods

impl<'a, VE: ValueEncoding> Entry<'a, VE>

pub fn or_insert(self, default: MetadataValue<VE>) -> &'a mut MetadataValue<VE>

Ensures a value is in the entry by inserting the default if empty.

Returns a mutable reference to the first value in the entry.

Examples

let mut map: MetadataMap = MetadataMap::default();

let keys = &[
    "content-length",
    "x-hello",
    "Content-Length",
    "x-world",
];

for &key in keys {
    let counter = map.entry(key)
        .expect("valid key names")
        .or_insert("".parse().unwrap());
    *counter = format!("{}{}", counter.to_str().unwrap(), "1").parse().unwrap();
}

assert_eq!(map.get("content-length").unwrap(), "11");
assert_eq!(map.get("x-hello").unwrap(), "1");

pub fn or_insert_with<F: FnOnce() -> MetadataValue<VE>>(
    self,
    default: F
) -> &'a mut MetadataValue<VE>

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 = MetadataMap::new();

let res = map.entry("x-hello").unwrap()
    .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 = MetadataMap::new();
map.insert("host", "world".parse().unwrap());

let res = map.entry("host")
    .expect("host is a valid string")
    .or_insert_with(|| unreachable!());


assert_eq!(res, "world");

pub fn key(&self) -> &MetadataKey<VE>

Returns a reference to the entry's key

Examples

let mut map = MetadataMap::new();

assert_eq!(map.entry("x-hello").unwrap().key(), "x-hello");

Trait Implementations

impl<'a, VE: Debug + ValueEncoding> Debug for Entry<'a, VE>

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.