http_types/other/
expect.rs

1use crate::ensure_eq_status;
2use crate::headers::{HeaderName, HeaderValue, Headers, ToHeaderValues, EXPECT};
3
4use std::fmt::Debug;
5use std::option;
6
7/// HTTP `Expect` header
8///
9/// [MDN Documentation](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Expect)
10///
11/// # Specifications
12///
13/// - [RFC 7231, section 5.1.1: Expect](https://tools.ietf.org/html/rfc7231#section-5.1.1)
14///
15/// # Examples
16///
17/// ```
18/// # fn main() -> http_types::Result<()> {
19/// #
20/// use http_types::Response;
21/// use http_types::other::Expect;
22///
23/// let expect = Expect::new();
24///
25/// let mut res = Response::new(200);
26/// expect.apply(&mut res);
27///
28/// let expect = Expect::from_headers(res)?.unwrap();
29/// assert_eq!(expect, Expect::new());
30/// #
31/// # Ok(()) }
32/// ```
33#[derive(Debug, Ord, PartialOrd, Eq, PartialEq)]
34pub struct Expect {
35    _priv: (),
36}
37
38impl Expect {
39    /// Create a new instance of `Expect`.
40    pub fn new() -> Self {
41        Self { _priv: () }
42    }
43
44    /// Create an instance of `Expect` from a `Headers` instance.
45    pub fn from_headers(headers: impl AsRef<Headers>) -> crate::Result<Option<Self>> {
46        let headers = match headers.as_ref().get(EXPECT) {
47            Some(headers) => headers,
48            None => return Ok(None),
49        };
50
51        // If we successfully parsed the header then there's always at least one
52        // entry. We want the last entry.
53        let header = headers.iter().last().unwrap();
54        ensure_eq_status!(header, "100-continue", 400, "malformed `Expect` header");
55
56        Ok(Some(Self { _priv: () }))
57    }
58
59    /// Insert a `HeaderName` + `HeaderValue` pair into a `Headers` instance.
60    pub fn apply(&self, mut headers: impl AsMut<Headers>) {
61        headers.as_mut().insert(EXPECT, self.value());
62    }
63
64    /// Get the `HeaderName`.
65    pub fn name(&self) -> HeaderName {
66        EXPECT
67    }
68
69    /// Get the `HeaderValue`.
70    pub fn value(&self) -> HeaderValue {
71        let value = "100-continue";
72        // SAFETY: the internal string is validated to be ASCII.
73        unsafe { HeaderValue::from_bytes_unchecked(value.into()) }
74    }
75}
76
77impl ToHeaderValues for Expect {
78    type Iter = option::IntoIter<HeaderValue>;
79    fn to_header_values(&self) -> crate::Result<Self::Iter> {
80        // A HeaderValue will always convert into itself.
81        Ok(self.value().to_header_values().unwrap())
82    }
83}
84
85#[cfg(test)]
86mod test {
87    use super::*;
88    use crate::headers::Headers;
89
90    #[test]
91    fn smoke() -> crate::Result<()> {
92        let expect = Expect::new();
93
94        let mut headers = Headers::new();
95        expect.apply(&mut headers);
96
97        let expect = Expect::from_headers(headers)?.unwrap();
98        assert_eq!(expect, Expect::new());
99        Ok(())
100    }
101
102    #[test]
103    fn bad_request_on_parse_error() {
104        let mut headers = Headers::new();
105        headers.insert(EXPECT, "<nori ate the tag. yum.>");
106        let err = Expect::from_headers(headers).unwrap_err();
107        assert_eq!(err.status(), 400);
108    }
109}
http_types/other/expect.rs

http_types/other/
expect.rs
