trait based event system

packages/html/src/events/composition.rs

@@ -1,10 +1,89 @@
 use dioxus_core::Event;
 
 pub type CompositionEvent = Event<CompositionData>;
-#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
-#[derive(Debug, Clone, PartialEq, Eq)]
+
 pub struct CompositionData {
-    pub data: String,
+    inner: Box<dyn HasCompositionData>,
+}
+
+impl std::fmt::Debug for CompositionData {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("CompositionData")
+            .field("data", &self.data())
+            .finish()
+    }
+}
+
+impl<E: HasCompositionData> From<E> for CompositionData {
+    fn from(e: E) -> Self {
+        Self { inner: Box::new(e) }
+    }
+}
+
+impl PartialEq for CompositionData {
+    fn eq(&self, other: &Self) -> bool {
+        self.data() == other.data()
+    }
+}
+
+impl CompositionData {
+    pub fn data(&self) -> String {
+        self.inner.data()
+    }
+
+    pub fn downcast<T: 'static>(&self) -> Option<&T> {
+        self.inner.as_any().downcast_ref()
+    }
+}
+
+#[cfg(feature = "serialize")]
+#[derive(serde::Serialize, serde::Deserialize)]
+struct SerializedCompositionData {
+    data: String,
+}
+
+#[cfg(feature = "serialize")]
+impl From<&CompositionData> for SerializedCompositionData {
+    fn from(data: &CompositionData) -> Self {
+        Self { data: data.data() }
+    }
+}
+
+#[cfg(feature = "serialize")]
+impl HasCompositionData for SerializedCompositionData {
+    fn data(&self) -> String {
+        self.data.clone()
+    }
+
+    fn as_any(&self) -> &dyn std::any::Any {
+        self
+    }
+}
+
+#[cfg(feature = "serialize")]
+impl serde::Serialize for CompositionData {
+    fn serialize<S: serde::Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
+        SerializedCompositionData::from(self).serialize(serializer)
+    }
+}
+
+#[cfg(feature = "serialize")]
+impl<'de> serde::Deserialize<'de> for CompositionData {
+    fn deserialize<D: serde::Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
+        let data = SerializedCompositionData::deserialize(deserializer)?;
+        Ok(Self {
+            inner: Box::new(data),
+        })
+    }
+}
+
+/// A trait for any object that has the data for a composition event
+pub trait HasCompositionData: std::any::Any {
+    /// The characters generated by the input method that raised the event
+    fn data(&self) -> String;
+
+    /// return self as Any
+    fn as_any(&self) -> &dyn std::any::Any;
 }
 
 impl_event! [