headers/
map_ext.rs

1use super::{Error, Header, HeaderValue};
2
3/// An extension trait adding "typed" methods to `http::HeaderMap`.
4pub trait HeaderMapExt: self::sealed::Sealed {
5    /// Inserts the typed `Header` into this `HeaderMap`.
6    fn typed_insert<H>(&mut self, header: H)
7    where
8        H: Header;
9
10    /// Tries to find the header by name, and then decode it into `H`.
11    fn typed_get<H>(&self) -> Option<H>
12    where
13        H: Header;
14
15    /// Tries to find the header by name, and then decode it into `H`.
16    fn typed_try_get<H>(&self) -> Result<Option<H>, Error>
17    where
18        H: Header;
19}
20
21impl HeaderMapExt for http::HeaderMap {
22    fn typed_insert<H>(&mut self, header: H)
23    where
24        H: Header,
25    {
26        let entry = self.entry(H::name());
27        let mut values = ToValues {
28            state: State::First(entry),
29        };
30        header.encode(&mut values);
31    }
32
33    fn typed_get<H>(&self) -> Option<H>
34    where
35        H: Header,
36    {
37        HeaderMapExt::typed_try_get(self).unwrap_or(None)
38    }
39
40    fn typed_try_get<H>(&self) -> Result<Option<H>, Error>
41    where
42        H: Header,
43    {
44        let mut values = self.get_all(H::name()).iter();
45        if values.size_hint() == (0, Some(0)) {
46            Ok(None)
47        } else {
48            H::decode(&mut values).map(Some)
49        }
50    }
51}
52
53struct ToValues<'a> {
54    state: State<'a>,
55}
56
57#[derive(Debug)]
58enum State<'a> {
59    First(http::header::Entry<'a, HeaderValue>),
60    Latter(http::header::OccupiedEntry<'a, HeaderValue>),
61    Tmp,
62}
63
64impl Extend<HeaderValue> for ToValues<'_> {
65    fn extend<T: IntoIterator<Item = HeaderValue>>(&mut self, iter: T) {
66        for value in iter {
67            let entry = match ::std::mem::replace(&mut self.state, State::Tmp) {
68                State::First(http::header::Entry::Occupied(mut e)) => {
69                    e.insert(value);
70                    e
71                }
72                State::First(http::header::Entry::Vacant(e)) => e.insert_entry(value),
73                State::Latter(mut e) => {
74                    e.append(value);
75                    e
76                }
77                State::Tmp => unreachable!("ToValues State::Tmp"),
78            };
79            self.state = State::Latter(entry);
80        }
81    }
82}
83
84mod sealed {
85    pub trait Sealed {}
86    impl Sealed for ::http::HeaderMap {}
87}
headers/map_ext.rs

headers/
map_ext.rs
