Merge pull request #266 from http-rs/expect

Add `other::Expect` header

src/other/expect.rs

@@ -0,0 +1,110 @@
+use crate::ensure_eq_status;
+use crate::headers::{HeaderName, HeaderValue, Headers, ToHeaderValues, EXPECT};
+
+use std::fmt::Debug;
+use std::option;
+
+/// HTTP `Expect` header
+///
+/// [MDN Documentation](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Expect)
+///
+/// # Specifications
+///
+/// - [RFC 7231, section 5.1.1: Expect](https://tools.ietf.org/html/rfc7231#section-5.1.1)
+///
+/// # Examples
+///
+/// ```
+/// # fn main() -> http_types::Result<()> {
+/// #
+/// use http_types::Response;
+/// use http_types::other::Expect;
+///
+/// let expect = Expect::new();
+///
+/// let mut res = Response::new(200);
+/// expect.apply(&mut res);
+///
+/// let expect = Expect::from_headers(res)?.unwrap();
+/// assert_eq!(expect, Expect::new());
+/// #
+/// # Ok(()) }
+/// ```
+#[derive(Debug, Ord, PartialOrd, Eq, PartialEq)]
+pub struct Expect {
+ _priv: (),
+}
+
+impl Expect {
+ /// Create a new instance of `Expect`.
+ pub fn new() -> Self {
+ Self { _priv: () }
+ }
+
+ /// Create an instance of `Expect` from a `Headers` instance.
+ pub fn from_headers(headers: impl AsRef<Headers>) -> crate::Result<Option<Self>> {
+ let headers = match headers.as_ref().get(EXPECT) {
+ Some(headers) => headers,
+ None => return Ok(None),
+ };
+
+ // If we successfully parsed the header then there's always at least one
+ // entry. We want the last entry.
+ let header = headers.iter().last().unwrap();
+ ensure_eq_status!(header, "100-continue", 400, "malformed `Expect` header");
+
+ Ok(Some(Self { _priv: () }))
+ }
+
+ /// Insert a `HeaderName` + `HeaderValue` pair into a `Headers` instance.
+ pub fn apply(&self, mut headers: impl AsMut<Headers>) {
+ headers.as_mut().insert(EXPECT, self.value());
+ }
+
+ /// Get the `HeaderName`.
+ pub fn name(&self) -> HeaderName {
+ EXPECT
+ }
+
+ /// Get the `HeaderValue`.
+ pub fn value(&self) -> HeaderValue {
+ let value = "100-continue";
+ // SAFETY: the internal string is validated to be ASCII.
+ unsafe { HeaderValue::from_bytes_unchecked(value.into()) }
+ }
+}
+
+impl ToHeaderValues for Expect {
+ type Iter = option::IntoIter<HeaderValue>;
+ fn to_header_values(&self) -> crate::Result<Self::Iter> {
+ // A HeaderValue will always convert into itself.
+ Ok(self.value().to_header_values().unwrap())
+ }
+}
+
+#[cfg(test)]
+mod test {
+ use super::*;
+ use crate::headers::Headers;
+
+ #[test]
+ fn smoke() -> crate::Result<()> {
+ let expect = Expect::new();
+
+ let mut headers = Headers::new();
+ expect.apply(&mut headers);
+
+ let expect = Expect::from_headers(headers)?.unwrap();
+ assert_eq!(expect, Expect::new());
+ Ok(())
+ }
+
+ #[test]
+ fn bad_request_on_parse_error() -> crate::Result<()> {
+ let mut headers = Headers::new();
+ headers.insert(EXPECT, "<nori ate the tag. yum.>");
+ let err = Expect::from_headers(headers).unwrap_err();
+ assert_eq!(err.status(), 400);
+ Ok(())
+ }
+}

src/other/mod.rs

@@ -1,5 +1,7 @@
 //! Miscellaneous HTTP headers.
 
 mod date;
+mod expect;
 
 pub use date::Date;
+pub use expect::Expect;