move code around a bit, use a Cow for string data

src/protocol/data.rs

@@ -1,4 +1,5 @@
 use bytes::Bytes;
+use std::borrow::Cow;
 
 /// Binary message data
 #[derive(Debug, Clone)]
@@ -72,78 +73,51 @@ impl AsMut<[u8]> for MessageData {
     }
 }
 
-/// String message data
-#[derive(Debug, Clone)]
-pub struct MessageStringData(MessageStringDataImpl);
+impl From<Vec<u8>> for MessageData {
+    fn from(data: Vec<u8>) -> MessageData {
+        MessageData(MessageDataImpl::Unique(data))
+    }
+}
 
-/// opaque inner type to allow modifying the implementation in the future
-#[derive(Debug, Clone)]
-enum MessageStringDataImpl {
-    Static(&'static str),
-    Unique(String),
+impl From<&'static [u8]> for MessageData {
+    fn from(data: &'static [u8]) -> MessageData {
+        MessageData(MessageDataImpl::Shared(Bytes::from_static(data)))
+    }
 }
 
-impl PartialEq for MessageStringData {
-    fn eq(&self, other: &MessageStringData) -> bool {
-        self.as_ref().eq(other.as_ref())
+impl From<Bytes> for MessageData {
+    fn from(data: Bytes) -> MessageData {
+        MessageData(MessageDataImpl::Shared(data))
     }
 }
 
-impl Eq for MessageStringData {}
+/// String message data
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct MessageStringData(Cow<'static, str>);
+
+impl<T: Into<Cow<'static, str>>> From<T> for MessageStringData {
+    fn from(str: T) -> Self {
+        MessageStringData(str.into())
+    }
+}
 
 impl From<MessageStringData> for String {
     fn from(data: MessageStringData) -> String {
-        match data.0 {
-            MessageStringDataImpl::Static(data) => data.into(),
-            MessageStringDataImpl::Unique(data) => data,
-        }
+        data.0.into()
     }
 }
 
 impl From<MessageStringData> for MessageData {
     fn from(data: MessageStringData) -> MessageData {
         match data.0 {
-            MessageStringDataImpl::Static(data) => MessageData::from(data.as_bytes()),
-            MessageStringDataImpl::Unique(data) => MessageData::from(data.into_bytes()),
+            Cow::Borrowed(data) => MessageData::from(data.as_bytes()),
+            Cow::Owned(data) => MessageData::from(data.into_bytes()),
         }
     }
 }
 
 impl AsRef<str> for MessageStringData {
     fn as_ref(&self) -> &str {
-        match &self.0 {
-            MessageStringDataImpl::Static(data) => *data,
-            MessageStringDataImpl::Unique(data) => data.as_ref(),
-        }
-    }
-}
-
-impl From<String> for MessageStringData {
-    fn from(string: String) -> MessageStringData {
-        MessageStringData(MessageStringDataImpl::Unique(string))
-    }
-}
-
-impl From<&'static str> for MessageStringData {
-    fn from(string: &'static str) -> MessageStringData {
-        MessageStringData(MessageStringDataImpl::Static(string))
-    }
-}
-
-impl From<Vec<u8>> for MessageData {
-    fn from(data: Vec<u8>) -> MessageData {
-        MessageData(MessageDataImpl::Unique(data))
-    }
-}
-
-impl From<&'static [u8]> for MessageData {
-    fn from(data: &'static [u8]) -> MessageData {
-        MessageData(MessageDataImpl::Shared(Bytes::from_static(data)))
-    }
-}
-
-impl From<Bytes> for MessageData {
-    fn from(data: Bytes) -> MessageData {
-        MessageData(MessageDataImpl::Shared(data))
+        self.0.as_ref()
     }
 }