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use std::fmt;
use util::IterExt;
/// The `Expect` header.
///
/// > The "Expect" header field in a request indicates a certain set of
/// > behaviors (expectations) that need to be supported by the server in
/// > order to properly handle this request. The only such expectation
/// > defined by this specification is 100-continue.
/// >
/// > Expect = "100-continue"
///
/// # Example
///
/// ```
/// # extern crate headers;
/// use headers::Expect;
///
/// let expect = Expect::CONTINUE;
/// ```
#[derive(Clone, PartialEq)]
pub struct Expect(());
impl Expect {
/// "100-continue"
pub const CONTINUE: Expect = Expect(());
}
impl ::Header for Expect {
fn name() -> &'static ::HeaderName {
&::http::header::EXPECT
}
fn decode<'i, I: Iterator<Item = &'i ::HeaderValue>>(values: &mut I) -> Result<Self, ::Error> {
values
.just_one()
.and_then(|value| {
if value == "100-continue" {
Some(Expect::CONTINUE)
} else {
None
}
})
.ok_or_else(::Error::invalid)
}
fn encode<E: Extend<::HeaderValue>>(&self, values: &mut E) {
values.extend(::std::iter::once(::HeaderValue::from_static(
"100-continue",
)));
}
}
impl fmt::Debug for Expect {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_tuple("Expect").field(&"100-continue").finish()
}
}
#[cfg(test)]
mod tests {
use super::super::test_decode;
use super::Expect;
#[test]
fn expect_continue() {
assert_eq!(
test_decode::<Expect>(&["100-continue"]),
Some(Expect::CONTINUE),
);
}
#[test]
fn expectation_failed() {
assert_eq!(test_decode::<Expect>(&["sandwich"]), None,);
}
#[test]
fn too_many_values() {
assert_eq!(
test_decode::<Expect>(&["100-continue", "100-continue"]),
None,
);
}
}