Struct awc::http::header::HeaderMap

pub struct HeaderMap { /* fields omitted */ }

A set of HTTP headers

HeaderMap is an multimap of HeaderName to values.

Methods

impl HeaderMap

pub fn new() -> HeaderMap

Create an empty HeaderMap.

The map will be created without any capacity. This function will not allocate.

pub fn with_capacity(capacity: usize) -> HeaderMap

Create an empty HeaderMap with the specified capacity.

The returned map will allocate internal storage in order to hold about capacity elements without reallocating. However, this is a "best effort" as there are usage patterns that could cause additional allocations before capacity headers are stored in the map.

More capacity than requested may be allocated.

pub fn len(&self) -> usize

Returns the number of keys stored in the map.

This number could be be less than or equal to actual headers stored in the map.

pub fn is_empty(&self) -> bool

Returns true if the map contains no elements.

pub fn clear(&mut self)

Clears the map, removing all key-value pairs. Keeps the allocated memory for reuse.

pub fn capacity(&self) -> usize

Returns the number of headers the map can hold without reallocating.

This number is an approximation as certain usage patterns could cause additional allocations before the returned capacity is filled.

pub fn reserve(&mut self, additional: usize)

Reserves capacity for at least additional more headers to be inserted into the HeaderMap.

The header map may reserve more space to avoid frequent reallocations. Like with with_capacity, this will be a "best effort" to avoid allocations until additional more headers are inserted. Certain usage patterns could cause additional allocations before the number is reached.

pub fn get<N>(&self, name: N) -> Option<&HeaderValue> where
    N: AsName, 

Returns a reference to the value associated with the key.

If there are multiple values associated with the key, then the first one is returned. Use get_all to get all values associated with a given key. Returns None if there are no values associated with the key.

Important traits for GetAll<'a>

impl<'a> Iterator for GetAll<'a> type Item = &'a HeaderValue;

pub fn get_all<N>(&self, name: N) -> GetAll where
    N: AsName, 

Returns a view of all values associated with a key.

The returned view does not incur any allocations and allows iterating the values associated with the key. See GetAll for more details. Returns None if there are no values associated with the key.

pub fn get_mut<N>(&mut self, name: N) -> Option<&mut HeaderValue> where
    N: AsName, 

Returns a mutable reference to the value associated with the key.

If there are multiple values associated with the key, then the first one is returned. Use entry to get all values associated with a given key. Returns None if there are no values associated with the key.

pub fn contains_key<N>(&self, key: N) -> bool where
    N: AsName, 

Returns true if the map contains a value for the specified key.

pub fn iter(&self) -> Iter

An iterator visiting all key-value pairs.

The iteration order is arbitrary, but consistent across platforms for the same crate version. Each key will be yielded once per associated value. So, if a key has 3 associated values, it will be yielded 3 times.

pub fn keys(&self) -> Keys

An iterator visiting all keys.

The iteration order is arbitrary, but consistent across platforms for the same crate version. Each key will be yielded only once even if it has multiple associated values.

pub fn insert(&mut self, key: HeaderName, val: HeaderValue)

Inserts a key-value pair into the map.

If the map did not previously have this key present, then None is returned.

If the map did have this key present, the new value is associated with the key and all previous values are removed. Note that only a single one of the previous values is returned. If there are multiple values that have been previously associated with the key, then the first one is returned. See insert_mult on OccupiedEntry for an API that returns all values.

The key is not updated, though; this matters for types that can be == without being identical.

pub fn append(&mut self, key: HeaderName, value: HeaderValue)

Inserts a key-value pair into the map.

If the map did not previously have this key present, then false is returned.

If the map did have this key present, the new value is pushed to the end of the list of values currently associated with the key. The key is not updated, though; this matters for types that can be == without being identical.

pub fn remove<N>(&mut self, key: N) where
    N: AsName, 

Removes all headers for a particular header name from the map.

Trait Implementations

impl Clone for HeaderMap

fn clone(&self) -> HeaderMap

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for HeaderMap

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

Formats the value using the given formatter.

impl From<HeaderMap<HeaderValue>> for HeaderMap

Convert http::HeaderMap to a HeaderMap

fn from(map: HeaderMap<HeaderValue>) -> HeaderMap

Performs the conversion.

impl<'a> IntoIterator for &'a HeaderMap

type Item = (&'a HeaderName, &'a HeaderValue)

The type of the elements being iterated over.

type IntoIter = Iter<'a>

Which kind of iterator are we turning this into?

fn into_iter(self) -> <&'a HeaderMap as IntoIterator>::IntoIter

Creates an iterator from a value.