attention: Replace parse_* and serialise with TryFrom<Element> and Into<Element>.

src/attention.rs

@@ -4,6 +4,8 @@
 // License, v. 2.0. If a copy of the MPL was not distributed with this
 // file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+use std::convert::TryFrom;
+
 use minidom::Element;
 
 use error::Error;
@@ -13,38 +15,45 @@ use ns;
 #[derive(Debug, Clone)]
 pub struct Attention;
 
-pub fn parse_attention(root: &Element) -> Result<Attention, Error> {
-    if !root.is("attention", ns::ATTENTION) {
-        return Err(Error::ParseError("This is not an attention element."));
+impl<'a> TryFrom<&'a Element> for Attention {
+    type Error = Error;
+
+    fn try_from(elem: &'a Element) -> Result<Attention, Error> {
+        if !elem.is("attention", ns::ATTENTION) {
+            return Err(Error::ParseError("This is not an attention element."));
+        }
+        for _ in elem.children() {
+            return Err(Error::ParseError("Unknown child in attention element."));
+        }
+        Ok(Attention)
     }
-    for _ in root.children() {
-        return Err(Error::ParseError("Unknown child in attention element."));
-    }
-    Ok(Attention)
 }
 
-pub fn serialise(_: &Attention) -> Element {
-    Element::builder("attention")
-            .ns(ns::ATTENTION)
-            .build()
+impl<'a> Into<Element> for &'a Attention {
+    fn into(self) -> Element {
+        Element::builder("attention")
+                .ns(ns::ATTENTION)
+                .build()
+    }
 }
 
 #[cfg(test)]
 mod tests {
+    use std::convert::TryFrom;
     use minidom::Element;
     use error::Error;
-    use attention;
+    use super::Attention;
 
     #[test]
     fn test_simple() {
         let elem: Element = "<attention xmlns='urn:xmpp:attention:0'/>".parse().unwrap();
-        attention::parse_attention(&elem).unwrap();
+        Attention::try_from(&elem).unwrap();
     }
 
     #[test]
     fn test_invalid_child() {
         let elem: Element = "<attention xmlns='urn:xmpp:attention:0'><coucou/></attention>".parse().unwrap();
-        let error = attention::parse_attention(&elem).unwrap_err();
+        let error = Attention::try_from(&elem).unwrap_err();
         let message = match error {
             Error::ParseError(string) => string,
             _ => panic!(),
@@ -55,8 +64,10 @@ mod tests {
     #[test]
     fn test_serialise() {
         let elem: Element = "<attention xmlns='urn:xmpp:attention:0'/>".parse().unwrap();
-        let attention = attention::Attention;
-        let elem2 = attention::serialise(&attention);
+        let attention = Attention;
+        let elem2: Element = (&attention).into();
+        let elem3: Element = (&attention).into();
         assert_eq!(elem, elem2);
+        assert_eq!(elem2, elem3);
     }
 }

src/lib.rs

@@ -13,6 +13,8 @@
 // License, v. 2.0. If a copy of the MPL was not distributed with this
 // file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+#![feature(try_from)]
+
 extern crate minidom;
 extern crate jid;
 extern crate base64;

src/message.rs

@@ -4,6 +4,7 @@
 // License, v. 2.0. If a copy of the MPL was not distributed with this
 // file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+use std::convert::TryFrom;
 use std::str::FromStr;
 
 use minidom::{Element, IntoElements, IntoAttributeValue};
@@ -20,7 +21,7 @@ use stanza_error;
 use chatstates;
 use receipts;
 use delay;
-use attention;
+use attention::Attention;
 use message_correct;
 use eme;
 
@@ -32,7 +33,7 @@ pub enum MessagePayload {
     ChatState(chatstates::ChatState),
     Receipt(receipts::Receipt),
     Delay(delay::Delay),
-    Attention(attention::Attention),
+    Attention(Attention),
     MessageCorrect(message_correct::Replace),
     ExplicitMessageEncryption(eme::ExplicitMessageEncryption),
 }
@@ -121,7 +122,7 @@ pub fn parse_message(root: &Element) -> Result<Message, Error> {
             Some(MessagePayload::Receipt(receipt))
         } else if let Ok(delay) = delay::parse_delay(elem) {
             Some(MessagePayload::Delay(delay))
-        } else if let Ok(attention) = attention::parse_attention(elem) {
+        } else if let Ok(attention) = Attention::try_from(elem) {
             Some(MessagePayload::Attention(attention))
         } else if let Ok(replace) = message_correct::parse_replace(elem) {
             Some(MessagePayload::MessageCorrect(replace))
@@ -148,7 +149,7 @@ pub fn serialise_payload(payload: &MessagePayload) -> Element {
     match *payload {
         MessagePayload::Body(ref body) => body::serialise(body),
         MessagePayload::StanzaError(ref stanza_error) => stanza_error::serialise(stanza_error),
-        MessagePayload::Attention(ref attention) => attention::serialise(attention),
+        MessagePayload::Attention(ref attention) => attention.into(),
         MessagePayload::ChatState(ref chatstate) => chatstates::serialise(chatstate),
         MessagePayload::Receipt(ref receipt) => receipts::serialise(receipt),
         MessagePayload::Delay(ref delay) => delay::serialise(delay),