hashes: Switch to Into/TryFrom.

src/hashes.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;
@@ -16,42 +18,46 @@ pub struct Hash {
     pub hash: String,
 }
 
-pub fn parse_hash(root: &Element) -> Result<Hash, Error> {
-    if !root.is("hash", ns::HASHES) {
-        return Err(Error::ParseError("This is not a hash element."));
+impl<'a> TryFrom<&'a Element> for Hash {
+    type Error = Error;
+
+    fn try_from(elem: &'a Element) -> Result<Hash, Error> {
+        if !elem.is("hash", ns::HASHES) {
+            return Err(Error::ParseError("This is not a hash element."));
+        }
+        for _ in elem.children() {
+            return Err(Error::ParseError("Unknown child in hash element."));
+        }
+        let algo = elem.attr("algo").ok_or(Error::ParseError("Mandatory argument 'algo' not present in hash element."))?.to_owned();
+        let hash = match elem.text().as_ref() {
+            "" => return Err(Error::ParseError("Hash element shouldn’t be empty.")),
+            text => text.to_owned(),
+        };
+        Ok(Hash {
+            algo: algo,
+            hash: hash,
+        })
     }
-    for _ in root.children() {
-        return Err(Error::ParseError("Unknown child in hash element."));
-    }
-    let algo = root.attr("algo").ok_or(Error::ParseError("Mandatory argument 'algo' not present in hash element."))?.to_owned();
-    let hash = match root.text().as_ref() {
-        "" => return Err(Error::ParseError("Hash element shouldn’t be empty.")),
-        text => text.to_owned(),
-    };
-    Ok(Hash {
-        algo: algo,
-        hash: hash,
-    })
 }
 
-pub fn serialise(hash: &Hash) -> Element {
-    Element::builder("hash")
-            .ns(ns::HASHES)
-            .attr("algo", hash.algo.clone())
-            .append(hash.hash.clone())
-            .build()
+impl<'a> Into<Element> for &'a Hash {
+    fn into(self) -> Element {
+        Element::builder("hash")
+                .ns(ns::HASHES)
+                .attr("algo", self.algo.clone())
+                .append(self.hash.clone())
+                .build()
+    }
 }
 
 #[cfg(test)]
 mod tests {
-    use minidom::Element;
-    use error::Error;
-    use hashes;
+    use super::*;
 
     #[test]
     fn test_simple() {
         let elem: Element = "<hash xmlns='urn:xmpp:hashes:2' algo='sha-256'>2XarmwTlNxDAMkvymloX3S5+VbylNrJt/l5QyPa+YoU=</hash>".parse().unwrap();
-        let hash = hashes::parse_hash(&elem).unwrap();
+        let hash = Hash::try_from(&elem).unwrap();
         assert_eq!(hash.algo, "sha-256");
         assert_eq!(hash.hash, "2XarmwTlNxDAMkvymloX3S5+VbylNrJt/l5QyPa+YoU=");
     }
@@ -59,7 +65,7 @@ mod tests {
     #[test]
     fn test_unknown() {
         let elem: Element = "<replace xmlns='urn:xmpp:message-correct:0'/>".parse().unwrap();
-        let error = hashes::parse_hash(&elem).unwrap_err();
+        let error = Hash::try_from(&elem).unwrap_err();
         let message = match error {
             Error::ParseError(string) => string,
             _ => panic!(),
@@ -70,7 +76,7 @@ mod tests {
     #[test]
     fn test_invalid_child() {
         let elem: Element = "<hash xmlns='urn:xmpp:hashes:2'><coucou/></hash>".parse().unwrap();
-        let error = hashes::parse_hash(&elem).unwrap_err();
+        let error = Hash::try_from(&elem).unwrap_err();
         let message = match error {
             Error::ParseError(string) => string,
             _ => panic!(),