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use super::{Error, Header, HeaderValue};
use http;
/// An extension trait adding "typed" methods to `http::HeaderMap`.
pub trait HeaderMapExt: self::sealed::Sealed {
/// Inserts the typed `Header` into this `HeaderMap`.
fn typed_insert<H>(&mut self, header: H)
where
H: Header;
/// Tries to find the header by name, and then decode it into `H`.
fn typed_get<H>(&self) -> Option<H>
where
H: Header;
/// Tries to find the header by name, and then decode it into `H`.
fn typed_try_get<H>(&self) -> Result<Option<H>, Error>
where
H: Header;
}
impl HeaderMapExt for http::HeaderMap {
fn typed_insert<H>(&mut self, header: H)
where
H: Header,
{
let entry = self.entry(H::name());
let mut values = ToValues {
state: State::First(entry),
};
header.encode(&mut values);
}
fn typed_get<H>(&self) -> Option<H>
where
H: Header,
{
HeaderMapExt::typed_try_get(self).unwrap_or(None)
}
fn typed_try_get<H>(&self) -> Result<Option<H>, Error>
where
H: Header,
{
let mut values = self.get_all(H::name()).iter();
if values.size_hint() == (0, Some(0)) {
Ok(None)
} else {
H::decode(&mut values).map(Some)
}
}
}
struct ToValues<'a> {
state: State<'a>,
}
#[derive(Debug)]
enum State<'a> {
First(http::header::Entry<'a, HeaderValue>),
Latter(http::header::OccupiedEntry<'a, HeaderValue>),
Tmp,
}
impl<'a> Extend<HeaderValue> for ToValues<'a> {
fn extend<T: IntoIterator<Item = HeaderValue>>(&mut self, iter: T) {
for value in iter {
let entry = match ::std::mem::replace(&mut self.state, State::Tmp) {
State::First(http::header::Entry::Occupied(mut e)) => {
e.insert(value);
e
}
State::First(http::header::Entry::Vacant(e)) => e.insert_entry(value),
State::Latter(mut e) => {
e.append(value);
e
}
State::Tmp => unreachable!("ToValues State::Tmp"),
};
self.state = State::Latter(entry);
}
}
}
mod sealed {
pub trait Sealed {}
impl Sealed for ::http::HeaderMap {}
}