Better serialization of complex types under `Vec<T>`

instant-xml/src/impls.rs

@@ -317,6 +317,7 @@ fn decode(input: &str) -> Cow<'_, str> {
     Cow::Owned(result)
 }
 
+const VEC_LIST_TAG: &str = "list";
 const VEC_ELEMENT_TAG: &str = "element";
 
 impl<'xml, T> FromXml<'xml> for Vec<T>
@@ -325,10 +326,11 @@ where
 {
     fn deserialize<'cx>(deserializer: &'cx mut Deserializer<'cx, 'xml>) -> Result<Self, Error> {
         let mut result = Self::new();
+        let kind = <T as FromXml<'xml>>::KIND;
 
         while let Some(Ok(node)) = deserializer.next() {
-            match node {
-                Node::Open(data) => {
+            match (&kind, node) {
+                (Kind::Scalar, Node::Open(data)) => {
                     let id = deserializer.element_id(&data)?;
 
                     match id.name {
@@ -339,6 +341,10 @@ where
                         _ => return Err(Error::UnexpectedState),
                     }
                 }
+                (Kind::Vec | Kind::Element(_), Node::Open(data)) => {
+                    let mut nested = deserializer.nested(data);
+                    result.push(<T as FromXml<'xml>>::deserialize(&mut nested)?)
+                }
                 _ => return Err(Error::UnexpectedState),
             }
         }
@@ -357,12 +363,30 @@ where
         &self,
         serializer: &mut Serializer<W>,
     ) -> Result<(), Error> {
+        match <T as ToXml>::KIND {
+            Kind::Element(_) => {
+                for i in self {
+                    i.serialize(serializer)?;
+                }
+            }
+            Kind::Scalar => {
                 for i in self {
                     let prefix = serializer.write_start(VEC_ELEMENT_TAG, "", false)?;
                     serializer.end_start()?;
                     i.serialize(serializer)?;
                     serializer.write_close(prefix, VEC_ELEMENT_TAG)?;
                 }
+            }
+            // this would be a Vec<Vec<T>>, where the internal field is unnamed
+            Kind::Vec => {
+                for i in self {
+                    let prefix = serializer.write_start(VEC_LIST_TAG, "", false)?;
+                    serializer.end_start()?;
+                    i.serialize(serializer)?;
+                    serializer.write_close(prefix, VEC_LIST_TAG)?;
+                }
+            }
+        }
 
         Ok(())
     }

instant-xml/tests/entities.rs

@@ -13,6 +13,33 @@ struct StructSpecialEntities<'a> {
     vec: Vec<String>,
 }
 
+#[derive(Debug, PartialEq, Eq, FromXml, ToXml)]
+#[xml(ns("URI"))]
+struct VecEntities<'a> {
+    complex: Vec<StructSpecialEntities<'a>>,
+    list1: Vec<String>,
+    list2: Vec<Vec<String>>,
+}
+
+#[test]
+fn vec_entities() {
+    let serialized = r#"<VecEntities xmlns="URI"><complex><StructSpecialEntities><string>&lt;&gt;&amp;&quot;&apos;adsad&quot;</string><str>str</str><cow>str&amp;</cow><vec><element xmlns="">one</element><element xmlns="">two</element><element xmlns="">three</element></vec></StructSpecialEntities></complex><list1><element xmlns="">a</element><element xmlns="">b</element></list1><list2><list xmlns=""><element xmlns="">a</element><element xmlns="">b</element></list></list2></VecEntities>"#;
+
+    let instance = VecEntities {
+        complex: vec![StructSpecialEntities {
+            string: String::from("<>&\"'adsad\""),
+            str: "str",
+            cow: Cow::Owned("str&".to_string()),
+            vec: vec!["one".into(), "two".into(), "three".into()],
+        }],
+        list1: vec!["a".into(), "b".into()],
+        list2: vec![vec!["a".into(), "b".into()]],
+    };
+
+    assert_eq!(to_string(&instance).unwrap(), serialized);
+    assert_eq!(from_str(serialized), Ok(instance));
+}
+
 #[test]
 fn escape_back() {
     assert_eq!(