add vary header, first draft

src/header/common/vary.rs

@@ -0,0 +1,59 @@
+use header::{Header, HeaderFormat, CaseInsensitive};
+use std::fmt::{mod};
+use super::util::{from_comma_delimited, fmt_comma_delimited, from_one_raw_str};
+
+/// The `Allow` header.
+/// See also https://tools.ietf.org/html/rfc7231#section-7.1.4
+
+#[deriving(Clone, PartialEq, Show)]
+pub enum Vary {
+    /// This corresponds to '*'.
+    Any,
+    /// The header field names which will influence the response representation.
+    Headers(Vec<CaseInsensitive>),
+}
+
+impl Header for Vary {
+    fn header_name(_: Option<Vary>) -> &'static str {
+        "Vary"
+    }
+
+    fn parse_header(raw: &[Vec<u8>]) -> Option<Vary> {
+        from_one_raw_str(raw).and_then(|s: String| {
+            let slice = s[];
+            match slice {
+                "" => None,
+                "*" => Some(Vary::Any),
+                _ => from_comma_delimited(raw).map(|vec| Vary::Headers(vec)),
+            }
+        })
+    }
+}
+
+impl HeaderFormat for Vary {
+    fn fmt_header(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            Vary::Any => { write!(fmt, "*") }
+            Vary::Headers(ref fields) => { fmt_comma_delimited(fmt, fields[]) }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Vary;
+    use header::{Header, CaseInsensitive};
+
+    #[test]
+    fn test_vary() {
+        let mut vary: Option<Vary>;
+
+        vary = Header::parse_header([b"*".to_vec()].as_slice());
+        assert_eq!(vary, Some(Vary::Any));
+
+        vary = Header::parse_header([b"etag,cookie,allow".to_vec()].as_slice());
+        assert_eq!(vary, Some(Vary::Headers(vec![from_str::<CaseInsensitive>("eTag").unwrap(),
+                                                 from_str::<CaseInsensitive>("cookIE").unwrap(),
+                                                 from_str::<CaseInsensitive>("AlLOw").unwrap(),])));
+    }
+}