Implement flatten (de)

yaserde/tests/deserializer.rs

@@ -647,3 +647,89 @@ fn de_custom() {
     }
   );
 }
+
+#[test]
+fn de_flatten() {
+  #[derive(Default, PartialEq, Debug, YaDeserialize)]
+  struct DateTime {
+    #[yaserde(flatten)]
+    date: Date,
+    time: String,
+    #[yaserde(flatten)]
+    kind: DateKind,
+  }
+
+  #[derive(Default, PartialEq, Debug, YaDeserialize)]
+  struct Date {
+    year: i32,
+    month: i32,
+    day: i32,
+    #[yaserde(flatten)]
+    extra: Extra,
+    #[yaserde(flatten)]
+    optional_extra: Option<OptionalExtra>,
+  }
+
+  #[derive(Default, PartialEq, Debug, YaDeserialize)]
+  pub struct Extra {
+    week: i32,
+    century: i32,
+  }
+
+  #[derive(Default, PartialEq, Debug, YaDeserialize)]
+  pub struct OptionalExtra {
+    lunar_day: i32,
+  }
+
+  #[derive(PartialEq, Debug, YaDeserialize)]
+  pub enum DateKind {
+    #[yaserde(rename = "holidays")]
+    Holidays(Vec<String>),
+    #[yaserde(rename = "working")]
+    Working,
+  }
+
+  impl Default for DateKind {
+    fn default() -> Self {
+      DateKind::Working
+    }
+  };
+
+  let content = r#"
+    <?xml version="1.0" encoding="utf-8"?>
+    <DateTime>
+      <year>2020</year>
+      <month>1</month>
+      <day>1</day>
+      <week>1</week>
+      <century>21</century>
+      <lunar_day>1</lunar_day>
+      <time>10:40:03</time>
+      <holidays>New Year's Day</holidays>
+      <holidays>Novy God Day</holidays>
+      <holidays>Polar Bear Swim Day</holidays>
+    </DateTime>
+  "#;
+  convert_and_validate!(
+    content,
+    DateTime,
+    DateTime {
+      date: Date {
+        year: 2020,
+        month: 1,
+        day: 1,
+        extra: Extra {
+          week: 1,
+          century: 21,
+        },
+        optional_extra: Some(OptionalExtra { lunar_day: 1 }),
+      },
+      time: "10:40:03".to_string(),
+      kind: DateKind::Holidays(vec![
+        "New Year's Day".into(),
+        "Novy God Day".into(),
+        "Polar Bear Swim Day".into()
+      ])
+    }
+  );
+}