feat(headers): add Warning header

Implements Warning header from RFC7234
Closes #883

src/header/common/mod.rs

@@ -58,6 +58,7 @@ pub use self::transfer_encoding::TransferEncoding;
 pub use self::upgrade::{Upgrade, Protocol, ProtocolName};
 pub use self::user_agent::UserAgent;
 pub use self::vary::Vary;
+pub use self::warning::Warning;
 
 #[doc(hidden)]
 #[macro_export]
@@ -420,3 +421,4 @@ mod transfer_encoding;
 mod upgrade;
 mod user_agent;
 mod vary;
+mod warning;

src/header/common/warning.rs

@@ -0,0 +1,174 @@
+use std::fmt;
+use std::str::{FromStr};
+use header::{Header, HttpDate, Raw};
+use header::parsing::from_one_raw_str;
+
+/// `Warning` header, defined in [RFC7234](https://tools.ietf.org/html/rfc7234#section-5.5)
+///
+/// The `Warning` header field can be be used to carry additional information
+/// about the status or transformation of a message that might not be reflected
+/// in the status code. This header is sometimes used as backwards
+/// compatible way to notify of a deprecated API. 
+///
+/// # ABNF
+/// ```plain
+/// Warning       = 1#warning-value
+/// warning-value = warn-code SP warn-agent SP warn-text
+///                                       [ SP warn-date ]
+/// warn-code  = 3DIGIT
+/// warn-agent = ( uri-host [ ":" port ] ) / pseudonym
+///                 ; the name or pseudonym of the server adding
+///                 ; the Warning header field, for use in debugging
+///                 ; a single "-" is recommended when agent unknown
+/// warn-text  = quoted-string
+/// warn-date  = DQUOTE HTTP-date DQUOTE
+/// ```
+///
+/// # Example values
+/// * `Warning: 112 - "network down" "Sat, 25 Aug 2012 23:34:45 GMT"`
+/// * `Warning: 299 - "Deprecated API " "Tue, 15 Nov 1994 08:12:31 GMT"`
+/// * `Warning: 299 api.hyper.rs:8080 "Deprecated API : use newapi.hyper.rs instead."`
+/// * `Warning: 299 api.hyper.rs:8080 "Deprecated API : use newapi.hyper.rs instead." "Tue, 15 Nov 1994 08:12:31 GMT"` 
+///
+/// # Examples
+/// ```
+/// use hyper::header::{Headers, Warning};
+/// 
+/// let mut headers = Headers::new();
+/// headers.set(
+///     Warning{
+///         code: 299,
+///         agent: "api.hyper.rs".to_owned(),
+///         text: "Deprecated".to_owned(),
+///         date: None
+///     }
+/// );
+/// ```
+/// ```
+/// use hyper::header::{Headers, HttpDate, Warning};
+/// 
+/// let mut headers = Headers::new();
+/// headers.set(
+///     Warning{
+///         code: 299,
+///         agent: "api.hyper.rs".to_owned(),
+///         text: "Deprecated".to_owned(),
+///         date: "Tue, 15 Nov 1994 08:12:31 GMT".parse::<HttpDate>().ok()
+///     }
+/// );
+/// ```
+/// ```
+/// # extern crate hyper;
+/// # extern crate time;
+/// # fn main() {
+/// use hyper::header::{Headers, HttpDate, Warning};
+/// 
+/// let mut headers = Headers::new();
+/// headers.set(
+///     Warning{
+///         code: 199,
+///         agent: "api.hyper.rs".to_owned(),
+///         text: "Deprecated".to_owned(),
+///         date: Some(HttpDate(time::now()))
+///     }
+/// );
+/// # }
+/// ```
+#[derive(PartialEq, Clone, Debug)]
+pub struct Warning {
+    /// The 3 digit warn code.
+    pub code: u16,
+    /// The name or pseudonym of the server adding this header.
+    pub agent: String,
+    /// The warning message describing the error.
+    pub text: String,
+    /// An optional warning date.
+    pub date: Option<HttpDate>
+}
+
+impl Header for Warning {
+    fn header_name() -> &'static str {
+        static NAME: &'static str = "Warning";
+        NAME
+    }
+
+    fn parse_header(raw: &Raw) -> ::Result<Warning> {
+        from_one_raw_str(raw)
+    }
+
+    fn fmt_header(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self.date {
+            Some(date) => write!(f, "{:03} {} \"{}\" \"{}\"", self.code, self.agent, self.text, date),
+            None => write!(f, "{:03} {} \"{}\"", self.code, self.agent, self.text)
+        }
+    }
+}
+
+impl FromStr for Warning {
+    type Err = ::Error;
+
+    fn from_str(s: &str) -> ::Result<Warning> {
+        let mut warning_split = s.split_whitespace();
+        let code = match warning_split.next() {
+            Some(c) => match c.parse::<u16>() {
+                Ok(c) => c,
+                Err(..) => return Err(::Error::Header)
+            },
+            None => return Err(::Error::Header)
+        };
+        let agent = match warning_split.next() {
+            Some(a) => a.to_string(),
+            None => return Err(::Error::Header)
+        };
+
+        let mut warning_split = s.split('"').skip(1);
+        let text = match warning_split.next() {
+            Some(t) => t.to_string(),
+            None => return Err(::Error::Header)
+        };
+        let date = match warning_split.skip(1).next() {
+            Some(d) => d.parse::<HttpDate>().ok(),
+            None => None // Optional
+        };
+
+        Ok(Warning {
+            code: code,
+            agent: agent,
+            text: text,
+            date: date
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Warning;
+    use header::{Header, HttpDate};
+
+    #[test]
+    fn test_parsing() {
+        let warning = Header::parse_header(&vec![b"112 - \"network down\" \"Sat, 25 Aug 2012 23:34:45 GMT\"".to_vec()].into());
+        assert_eq!(warning.ok(), Some(Warning {
+            code: 112,
+            agent: "-".to_owned(),
+            text: "network down".to_owned(),
+            date: "Sat, 25 Aug 2012 23:34:45 GMT".parse::<HttpDate>().ok()
+        }));
+
+        let warning = Header::parse_header(&vec![b"299 api.hyper.rs:8080 \"Deprecated API : use newapi.hyper.rs instead.\"".to_vec()].into());
+        assert_eq!(warning.ok(), Some(Warning {
+            code: 299,
+            agent: "api.hyper.rs:8080".to_owned(),
+            text: "Deprecated API : use newapi.hyper.rs instead.".to_owned(),
+            date: None
+        }));
+
+        let warning = Header::parse_header(&vec![b"299 api.hyper.rs:8080 \"Deprecated API : use newapi.hyper.rs instead.\" \"Tue, 15 Nov 1994 08:12:31 GMT\"".to_vec()].into());
+        assert_eq!(warning.ok(), Some(Warning {
+            code: 299,
+            agent: "api.hyper.rs:8080".to_owned(),
+            text: "Deprecated API : use newapi.hyper.rs instead.".to_owned(),
+            date: "Tue, 15 Nov 1994 08:12:31 GMT".parse::<HttpDate>().ok()
+        }));
+    }
+}