refactor(headers): Use header!() macro for 3 headers with a "*" value

`If-Match`, `If-None-Match` and `Vary` headers are either a "*" value meaning that the header
matches every possible item or a list of items, one of them must be matched to fulfil the condition.

BREAKING CHANGE: `If-Match`, `If-None-Match` and `Vary` item variant name changed to `Items`

Author: pyfisch

src/header/common/if_match.rs

@@ -1,51 +1,31 @@
-use header::{EntityTag, Header, HeaderFormat};
-use header::parsing::{from_comma_delimited, fmt_comma_delimited, from_one_raw_str};
-use std::fmt;
+use header::EntityTag;
 
-/// 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[..])
-        }
-    }
+header! {
+    #[doc="`If-Match` header, defined in"]
+    #[doc="[RFC7232](https://tools.ietf.org/html/rfc7232#section-3.1)"]
+    #[doc=""]
+    #[doc="The `If-Match` header field makes the request method conditional on"]
+    #[doc="the recipient origin server either having at least one current"]
+    #[doc="representation of the target resource, when the field-value is \"*\","]
+    #[doc="or having a current representation of the target resource that has an"]
+    #[doc="entity-tag matching a member of the list of entity-tags provided in"]
+    #[doc="the field-value."]
+    #[doc=""]
+    #[doc="An origin server MUST use the strong comparison function when"]
+    #[doc="comparing entity-tags for `If-Match`, since the client"]
+    #[doc="intends this precondition to prevent the method from being applied if"]
+    #[doc="there have been any changes to the representation data."]
+    #[doc=""]
+    #[doc="# ABNF"]
+    #[doc="```plain"]
+    #[doc="If-Match = \"*\" / 1#entity-tag"]
+    #[doc="```"]
+    (IfMatch, "If-Match") => {Any / (EntityTag)+}
 }
 
 #[test]
 fn test_parse_header() {
+    use header::Header;
     {
         let a: IfMatch = Header::parse_header(
         [b"*".to_vec()].as_ref()).unwrap();
@@ -54,7 +34,7 @@ fn test_parse_header() {
     {
         let a: IfMatch = Header::parse_header(
             [b"\"xyzzy\", \"r2d2xxxx\", \"c3piozzzz\"".to_vec()].as_ref()).unwrap();
-        let b = IfMatch::EntityTags(
+        let b = IfMatch::Items(
             vec![EntityTag::new(false, "xyzzy".to_string()),
                  EntityTag::new(false, "r2d2xxxx".to_string()),
                  EntityTag::new(false, "c3piozzzz".to_string())]);

src/header/common/if_none_match.rs

@@ -1,8 +1,28 @@
-use header::{Header, HeaderFormat, EntityTag};
-use header::parsing::{from_comma_delimited, fmt_comma_delimited, from_one_raw_str};
-use std::fmt::{self};
+use header::EntityTag;
 
-/// The `If-None-Match` header defined by HTTP/1.1.
+header! {
+    #[doc="`If-None-Match` header, defined in"]
+    #[doc="[RFC7232](https://tools.ietf.org/html/rfc7232#section-3.2)"]
+    #[doc=""]
+    #[doc="The `If-None-Match` header field makes the request method conditional"]
+    #[doc="on a recipient cache or origin server either not having any current"]
+    #[doc="representation of the target resource, when the field-value is \"*\","]
+    #[doc="or having a selected representation with an entity-tag that does not"]
+    #[doc="match any of those listed in the field-value."]
+    #[doc=""]
+    #[doc="A recipient MUST use the weak comparison function when comparing"]
+    #[doc="entity-tags for If-None-Match (Section 2.3.2), since weak entity-tags"]
+    #[doc="can be used for cache validation even if there have been changes to"]
+    #[doc="the representation data."]
+    #[doc=""]
+    #[doc="# ABNF"]
+    #[doc="```plain"]
+    #[doc="If-None-Match = \"*\" / 1#entity-tag"]
+    #[doc="```"]
+    (IfNoneMatch, "If-None-Match") => {Any / (EntityTag)+}
+}
+
+/*/// The `If-None-Match` header defined by HTTP/1.1.
 ///
 /// The "If-None-Match" header field makes the request method conditional
 /// on a recipient cache or origin server either not having any current
@@ -50,7 +70,7 @@ impl HeaderFormat for IfNoneMatch {
             IfNoneMatch::EntityTags(ref fields) => { fmt_comma_delimited(fmt, &fields[..]) }
         }
     }
-}
+}*/
 
 #[cfg(test)]
 mod tests {
@@ -71,7 +91,7 @@ mod tests {
         let weak_etag = EntityTag::new(true, "weak-etag".to_string());
         entities.push(foobar_etag);
         entities.push(weak_etag);
-        assert_eq!(if_none_match, Some(IfNoneMatch::EntityTags(entities)));
+        assert_eq!(if_none_match, Some(IfNoneMatch::Items(entities)));
     }
 }
 

src/header/common/mod.rs

@@ -173,6 +173,47 @@ macro_rules! header {
             }
         }
     };
+    // List header, one or more items with "*" option
+    ($(#[$a:meta])*($id:ident, $n:expr) => {Any / ($item:ty)+}) => {
+        $(#[$a])*
+        #[derive(Clone, Debug, PartialEq)]
+        pub enum $id {
+            /// Any value is a match
+            Any,
+            /// Only the listed items are a match
+            Items(Vec<$item>),
+        }
+        impl $crate::header::Header for $id {
+            fn header_name() -> &'static str {
+                $n
+            }
+            fn parse_header(raw: &[Vec<u8>]) -> Option<Self> {
+                // FIXME: Return None if no item is in $id::Only
+                if raw.len() == 1 {
+                    if raw[0] == b"*" {
+                        return Some($id::Any)
+                    } else if raw[0] == b"" {
+                        return None
+                    }
+                }
+                $crate::header::parsing::from_comma_delimited(raw).map(|vec| $id::Items(vec))
+            }
+        }
+        impl $crate::header::HeaderFormat for $id {
+            fn fmt_header(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+                match *self {
+                    $id::Any => write!(f, "*"),
+                    $id::Items(ref fields) => $crate::header::parsing::fmt_comma_delimited(f, &fields[..])
+                }
+            }
+        }
+        impl ::std::fmt::Display for $id {
+            fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+                use $crate::header::HeaderFormat;
+                self.fmt_header(f)
+            }
+        }
+    };
 }
 
 mod access_control;

src/header/common/vary.rs

@@ -1,9 +1,23 @@
-use header::{Header, HeaderFormat};
-use std::fmt::{self};
-use header::parsing::{from_comma_delimited, fmt_comma_delimited, from_one_raw_str};
 use unicase::UniCase;
 
-/// The `Allow` header.
+header! {
+    #[doc="`Vary` header, defined in [RFC7231](https://tools.ietf.org/html/rfc7231#section-7.1.4)"]
+    #[doc=""]
+    #[doc="The \"Vary\" header field in a response describes what parts of a"]
+    #[doc="request message, aside from the method, Host header field, and"]
+    #[doc="request target, might influence the origin server's process for"]
+    #[doc="selecting and representing this response.  The value consists of"]
+    #[doc="either a single asterisk (\"*\") or a list of header field names"]
+    #[doc="(case-insensitive)."]
+    #[doc=""]
+    #[doc="# ABNF"]
+    #[doc="```plain"]
+    #[doc="Vary = \"*\" / 1#field-name"]
+    #[doc="```"]
+    (Vary, "Vary") => {Any / (UniCase<String>)+}
+}
+
+/*/// The `Allow` header.
 /// See also https://tools.ietf.org/html/rfc7231#section-7.1.4
 
 #[derive(Clone, PartialEq, Debug)]
@@ -38,7 +52,7 @@ impl HeaderFormat for Vary {
             Vary::Headers(ref fields) => { fmt_comma_delimited(fmt, &fields[..]) }
         }
     }
-}
+}*/
 
 #[cfg(test)]
 mod tests {
@@ -53,8 +67,8 @@ mod tests {
         assert_eq!(vary, Some(Vary::Any));
 
         vary = Header::parse_header([b"etag,cookie,allow".to_vec()].as_ref());
-        assert_eq!(vary, Some(Vary::Headers(vec!["eTag".parse().unwrap(),
-                                                 "cookIE".parse().unwrap(),
-                                                 "AlLOw".parse().unwrap(),])));
+        assert_eq!(vary, Some(Vary::Items(vec!["eTag".parse().unwrap(),
+                                                "cookIE".parse().unwrap(),
+                                                "AlLOw".parse().unwrap(),])));
     }
 }