add bits to deal with Upgrade requests

src/header/common/upgrade.rs

@@ -0,0 +1,51 @@
+use header::Header;
+use std::fmt::{mod, Show};
+use super::{from_comma_delimited, fmt_comma_delimited};
+use std::from_str::FromStr;
+
+/// The `Upgrade` header.
+#[deriving(Clone, PartialEq, Show)]
+pub struct Upgrade(Vec<Protocol>);
+
+/// Protocol values that can appear in the Upgrade header.
+#[deriving(Clone, PartialEq)]
+pub enum Protocol {
+    /// The websocket protocol.
+    WebSocket,
+    /// Some other less common protocol.
+    ProtocolExt(String),
+}
+
+impl FromStr for Protocol {
+    fn from_str(s: &str) -> Option<Protocol> {
+        match s {
+            "websocket" => Some(WebSocket),
+            s => Some(ProtocolExt(s.to_string()))
+        }
+    }
+}
+
+impl fmt::Show for Protocol {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            WebSocket => "websocket",
+            ProtocolExt(ref s) => s.as_slice()
+        }.fmt(fmt)
+    }
+}
+
+impl Header for Upgrade {
+    fn header_name(_: Option<Upgrade>) -> &'static str {
+        "Upgrade"
+    }
+
+    fn parse_header(raw: &[Vec<u8>]) -> Option<Upgrade> {
+        from_comma_delimited(raw).map(|vec| Upgrade(vec))
+    }
+
+    fn fmt_header(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let Upgrade(ref parts) = *self;
+        fmt_comma_delimited(fmt, parts[])
+    }
+}
+