Restructure the entire editor codebase to consistently match the message hierarchy

Closes #744

editor/src/utility_traits.rs

@@ -0,0 +1,51 @@
+pub use crate::dispatcher::*;
+use crate::messages::prelude::*;
+
+use std::collections::VecDeque;
+
+/// Implements a message handler struct for a separate message struct.
+/// - The first generic argument (`M`) is that message struct type, representing a message enum variant to be matched and handled in `process_message()`.
+/// - The second generic argument (`D`) is the type of data that can be passed along by the caller to `process_message()`.
+pub trait MessageHandler<M: ToDiscriminant, D>
+where
+	M::Discriminant: AsMessage,
+	<M::Discriminant as TransitiveChild>::TopParent: TransitiveChild<Parent = <M::Discriminant as TransitiveChild>::TopParent, TopParent = <M::Discriminant as TransitiveChild>::TopParent> + AsMessage,
+{
+	/// Return true if the Action is consumed.
+	fn process_message(&mut self, message: M, data: D, responses: &mut VecDeque<Message>);
+
+	fn actions(&self) -> ActionList;
+}
+
+pub type ActionList = Vec<Vec<MessageDiscriminant>>;
+
+pub trait AsMessage: TransitiveChild
+where
+	Self::TopParent: TransitiveChild<Parent = Self::TopParent, TopParent = Self::TopParent> + AsMessage,
+{
+	fn local_name(self) -> String;
+	fn global_name(self) -> String {
+		<Self as Into<Self::TopParent>>::into(self).local_name()
+	}
+}
+
+// TODO: Add Send + Sync requirement
+// Use something like rw locks for synchronization
+pub trait MessageHandlerData {}
+
+pub trait ToDiscriminant {
+	type Discriminant;
+
+	fn to_discriminant(&self) -> Self::Discriminant;
+}
+
+pub trait TransitiveChild: Into<Self::Parent> + Into<Self::TopParent> {
+	type TopParent;
+	type Parent;
+}
+
+use std::collections::HashMap;
+
+pub trait Hint {
+	fn hints(&self) -> HashMap<String, String>;
+}