feat(headers): add IfMatch header

Add support for the If-Match http header.

src/header/common/if_match.rs

@@ -0,0 +1,68 @@
+use header::{EntityTag, Header, HeaderFormat};
+use header::parsing::{from_comma_delimited, fmt_comma_delimited, from_one_raw_str};
+use std::fmt;
+
+/// The `If-Match` header
+///
+/// The `If-Match` request-header field is used with a method to make
+/// it conditional.  The client provides a list of entity tags, and
+/// the request is only executed if one of those tags matches the
+/// current entity.
+///
+/// See http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.24
+#[derive(Clone, PartialEq, Debug)]
+pub enum IfMatch {
+    /// This corresponds to '*'.
+    Any,
+    /// The header field names which will influence the response representation.
+    EntityTags(Vec<EntityTag>)
+}
+
+impl Header for IfMatch {
+    fn header_name() -> &'static str {
+        "If-Match"
+    }
+
+    fn parse_header(raw: &[Vec<u8>]) -> Option<IfMatch> {
+        from_one_raw_str(raw).and_then(|s: String| {
+            let slice = &s[];
+            match slice {
+                "" => None,
+                "*" => Some(IfMatch::Any),
+                _ => from_comma_delimited(raw).map(IfMatch::EntityTags),
+            }
+        })
+    }
+}
+
+impl HeaderFormat for IfMatch {
+    fn fmt_header(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            IfMatch::Any => write!(fmt, "*"),
+            IfMatch::EntityTags(ref fields) => fmt_comma_delimited(fmt, &fields[])
+        }
+    }
+}
+
+#[test]
+fn test_parse_header() {
+    {
+        let a: IfMatch = Header::parse_header(
+        [b"*".to_vec()].as_slice()).unwrap();
+        assert_eq!(a, IfMatch::Any);
+    }
+    {
+        let a: IfMatch = Header::parse_header(
+            [b"\"xyzzy\", \"r2d2xxxx\", \"c3piozzzz\"".to_vec()].as_slice()).unwrap();
+        let b = IfMatch::EntityTags(
+            vec![EntityTag{weak:false, tag: "xyzzy".to_string()},
+                 EntityTag{weak:false, tag: "r2d2xxxx".to_string()},
+                 EntityTag{weak:false, tag: "c3piozzzz".to_string()}]);
+        assert_eq!(a, b);
+    }
+}
+
+bench_header!(star, IfMatch, { vec![b"*".to_vec()] });
+bench_header!(single , IfMatch, { vec![b"\"xyzzy\"".to_vec()] });
+bench_header!(multi, IfMatch,
+              { vec![b"\"xyzzy\", \"r2d2xxxx\", \"c3piozzzz\"".to_vec()] });

src/header/common/mod.rs

@@ -20,6 +20,7 @@ pub use self::date::Date;
 pub use self::etag::Etag;
 pub use self::expires::Expires;
 pub use self::host::Host;
+pub use self::if_match::IfMatch;
 pub use self::if_modified_since::IfModifiedSince;
 pub use self::if_none_match::IfNoneMatch;
 pub use self::if_unmodified_since::IfUnmodifiedSince;
@@ -157,6 +158,7 @@ mod date;
 mod etag;
 mod expires;
 mod host;
+mod if_match;
 mod last_modified;
 mod if_modified_since;
 mod if_none_match;