creating a ContentCoding type defined via a macro

Author: ParkMyCar

src/common/content_coding.rs

@@ -0,0 +1,78 @@
+macro_rules! define_content_coding {
+    ($($coding:ident; $str:expr,)+) => {   
+        #[derive(Copy, Clone, Debug, Eq, PartialEq)]
+        /// Values that are used with headers like `Content-Encoding`
+        /// [RFC7231](https://www.iana.org/assignments/http-parameters/http-parameters.xhtml)
+        /// 
+        pub enum ContentCoding {
+            $(
+                #[doc = $str]
+                $coding,
+            )+
+        }
+
+        impl ContentCoding {
+            /// Returns a static str for a ContentCoding
+            #[inline]
+            pub fn to_static(&self) -> &'static str {
+                match *self {
+                    $(ContentCoding::$coding => $str,)+
+                }
+            }
+        }
+
+        impl std::string::ToString for ContentCoding {
+            #[inline]
+            fn to_string(&self) -> String {
+                match *self {
+                    $(ContentCoding::$coding => $str.to_string(),)+
+                }
+            }
+        }
+
+        impl std::str::FromStr for ContentCoding {
+            type Err = &'static str;
+
+            fn from_str(s: &str) -> Result<Self, Self::Err> {
+                match s {
+                    $(
+                        stringify!($coding)
+                        | $str => Ok(ContentCoding::$coding),
+                    )+
+                    _ => Err("invalid content coding")
+                }
+            }
+        }
+    }
+}
+
+define_content_coding! {
+    BROTLI; "br",
+    COMPRESS; "compress",
+    DEFLATE; "deflate",
+    GZIP; "gzip",
+    IDENTITY; "identity",
+}
+
+#[cfg(test)]
+mod tests {
+    use super::ContentCoding;
+    use std::str::FromStr;
+
+    #[test]
+    fn to_static() {
+        assert_eq!(ContentCoding::GZIP.to_static(), "gzip");
+    }
+
+    #[test]
+    fn to_string() {
+        assert_eq!(ContentCoding::DEFLATE.to_string(), "deflate".to_string());
+    }
+
+    #[test]
+    fn from_str() {
+        assert_eq!(ContentCoding::from_str("br"), Ok(ContentCoding::BROTLI));
+        assert_eq!(ContentCoding::from_str("GZIP"), Ok(ContentCoding::GZIP));
+        assert_eq!(ContentCoding::from_str("blah blah"), Err("invalid content coding"));
+    }
+}

src/common/content_encoding.rs

@@ -39,35 +39,30 @@ derive_header! {
     name: CONTENT_ENCODING
 }
 
-impl ContentEncoding {
-    /// A constructor to easily create a `Content-Encoding: gzip` header.
-    #[inline]
-    pub fn gzip() -> ContentEncoding {
-        ContentEncoding(HeaderValue::from_static("gzip").into())
-    }
-
-    /// A constructor to easily create a `Content-Encoding: compress` header.
-    #[inline]
-    pub fn compress() -> ContentEncoding {
-        ContentEncoding(HeaderValue::from_static("compress").into())
-    }
-
-    /// A constructor to easily create a `Content-Encoding: deflate` header.
-    #[inline]
-    pub fn deflate() -> ContentEncoding {
-        ContentEncoding(HeaderValue::from_static("deflate").into())
-    }
-
-    /// A constructor to easily create a `Content-Encoding: identity` header.
-    #[inline]
-    pub fn identity() -> ContentEncoding {
-        ContentEncoding(HeaderValue::from_static("identity").into())
-    }
+macro_rules! derive_constructor {
+    ($(doc = $doc:expr; $coding:ident,)+) => {
+        $(
+            #[doc = $doc]
+            #[inline]
+            pub fn $coding() -> ContentEncoding {
+                ContentEncoding(HeaderValue::from_static(stringify!($coding)).into())
+            }
+        )+
+    };
+}
 
-    /// A constructor to easily create a `Content-Encoding: br` header.
-    #[inline]
-    pub fn br() -> ContentEncoding {
-        ContentEncoding(HeaderValue::from_static("br").into())
+impl ContentEncoding {
+    derive_constructor! {
+        doc = "A constructor to easily create a `Content-Encoding`: gzip header";
+        gzip,
+        doc = "A constructor to easily create a `Content-Encoding`: compress header";
+        compress,
+        doc = "A constructor to easily create a `Content-Encoding`: deflate header";
+        deflate,
+        doc = "A constructor to easily create a `Content-Encoding`: identity header";
+        identity,
+        doc = "A constructor to easily create a `Content-Encoding`: br header";
+        br,
     }
 
     /// Check if this header contains a given "coding".

src/common/mod.rs

@@ -23,6 +23,7 @@ pub use self::allow::Allow;
 pub use self::authorization::Authorization;
 pub use self::cache_control::CacheControl;
 pub use self::connection::Connection;
+pub use self::content_coding::ContentCoding;
 pub use self::content_disposition::ContentDisposition;
 pub use self::content_encoding::ContentEncoding;
 //pub use self::content_language::ContentLanguage;
@@ -142,6 +143,7 @@ mod allow;
 pub mod authorization;
 mod cache_control;
 mod connection;
+mod content_coding;
 mod content_disposition;
 mod content_encoding;
 //mod content_language;