feat(headers): adds Accept

Moved utils to shared/. Added quality_value.

src/header/common/accept_encoding.rs

@@ -0,0 +1,39 @@
+use std::fmt;
+
+use header;
+use header::shared;
+
+/// The `Accept-Encoding` header
+///
+/// The `Accept-Encoding` header can be used by clients to indicate what
+/// response encodings they accept.
+#[deriving(Clone, PartialEq, Show)]
+pub struct AcceptEncoding(pub Vec<shared::QualityItem<shared::Encoding>>);
+
+deref!(AcceptEncoding -> Vec<shared::QualityItem<shared::Encoding>>);
+
+impl header::Header for AcceptEncoding {
+    fn header_name(_: Option<AcceptEncoding>) -> &'static str {
+        "AcceptEncoding"
+    }
+
+    fn parse_header(raw: &[Vec<u8>]) -> Option<AcceptEncoding> {
+        shared::from_comma_delimited(raw).map(AcceptEncoding)
+    }
+}
+
+impl header::HeaderFormat for AcceptEncoding {
+    fn fmt_header(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        shared::fmt_comma_delimited(fmt, self[])
+    }
+}
+
+#[test]
+fn test_parse_header() {
+    let a: AcceptEncoding = header::Header::parse_header([b"gzip;q=1.0, identity; q=0.5".to_vec()].as_slice()).unwrap();
+    let b = AcceptEncoding(vec![
+        shared::QualityItem{item: shared::Gzip, quality: 1f32},
+        shared::QualityItem{item: shared::Identity, quality: 0.5f32},
+    ]);
+    assert_eq!(a, b);
+}