Add node introspection API

Closes #1110

Test Plan: query the introspectNode Endpoint from js

Reviewers: 

Pull Request: https://github.com/GraphiteEditor/Graphite/pull/1183

editor/src/dispatcher.rs

@@ -8,12 +8,12 @@ use graphene_core::text::Font;
 pub struct Dispatcher {
 	message_queues: Vec<VecDeque<Message>>,
 	pub responses: Vec<FrontendMessage>,
-	message_handlers: DispatcherMessageHandlers,
+	pub message_handlers: DispatcherMessageHandlers,
 }
 
 #[remain::sorted]
 #[derive(Debug, Default)]
-struct DispatcherMessageHandlers {
+pub struct DispatcherMessageHandlers {
 	broadcast_message_handler: BroadcastMessageHandler,
 	debug_message_handler: DebugMessageHandler,
 	dialog_message_handler: DialogMessageHandler,
@@ -21,7 +21,7 @@ struct DispatcherMessageHandlers {
 	input_preprocessor_message_handler: InputPreprocessorMessageHandler,
 	key_mapping_message_handler: KeyMappingMessageHandler,
 	layout_message_handler: LayoutMessageHandler,
-	portfolio_message_handler: PortfolioMessageHandler,
+	pub portfolio_message_handler: PortfolioMessageHandler,
 	preferences_message_handler: PreferencesMessageHandler,
 	tool_message_handler: ToolMessageHandler,
 	workspace_message_handler: WorkspaceMessageHandler,

editor/src/messages/portfolio/portfolio_message_handler.rs

@@ -16,7 +16,7 @@ use document_legacy::layers::layer_info::LayerDataType;
 use document_legacy::layers::style::RenderData;
 use document_legacy::Operation as DocumentOperation;
 use graph_craft::document::value::TaggedValue;
-use graph_craft::document::NodeInput;
+use graph_craft::document::{NodeId, NodeInput};
 use graphene_core::raster::Image;
 use graphene_core::text::Font;
 
@@ -606,6 +606,10 @@ impl MessageHandler<PortfolioMessage, (&InputPreprocessorMessageHandler, &Prefer
 }
 
 impl PortfolioMessageHandler {
+	pub fn introspect_node(&self, node_path: &[NodeId]) -> Option<String> {
+		self.executor.introspect_node(node_path)
+	}
+
 	pub fn document(&self, document_id: u64) -> Option<&DocumentMessageHandler> {
 		self.documents.get(&document_id)
 	}

editor/src/node_graph_executor.rs

@@ -51,6 +51,10 @@ impl NodeGraphExecutor {
 		}
 	}
 
+	pub fn introspect_node(&self, path: &[NodeId]) -> Option<String> {
+		self.executor.introspect(path).flatten()
+	}
+
 	/// Computes an input for a node in the graph
 	pub fn compute_input<T: dyn_any::StaticType>(&mut self, old_network: &NodeNetwork, node_path: &[NodeId], mut input_index: usize, editor_api: Cow<EditorApi<'_>>) -> Result<T, String> {
 		let mut network = old_network.clone();

frontend/wasm/src/editor_api.rs

@@ -697,6 +697,25 @@ impl JsEditorHandle {
 		let message = DocumentMessage::ToggleLayerExpansion { layer_path };
 		self.dispatch(message);
 	}
+
+	/// Returns the string representation of the nodes contents
+	#[wasm_bindgen(js_name = introspectNode)]
+	pub fn introspect_node(&self, node_path: Vec<NodeId>) -> Option<String> {
+		let frontend_messages = EDITOR_INSTANCES.with(|instances| {
+			// Mutably borrow the editors, and if successful, we can access them in the closure
+			instances.try_borrow_mut().map(|mut editors| {
+				// Get the editor instance for this editor ID, then dispatch the message to the backend, and return its response `FrontendMessage` queue
+				editors
+					.get_mut(&self.editor_id)
+					.expect("EDITOR_INSTANCES does not contain the current editor_id")
+					.dispatcher
+					.message_handlers
+					.portfolio_message_handler
+					.introspect_node(&node_path)
+			})
+		});
+		frontend_messages.unwrap()
+	}
 }
 
 // Needed to make JsEditorHandle functions pub to Rust.

node-graph/graph-craft/src/proto.rs

@@ -275,7 +275,7 @@ impl ProtoNetwork {
 		let paths = self.nodes.iter().map(|(_, node)| node.document_node_path.clone()).collect::<Vec<_>>();
 
 		let resolved_lookup = resolved.clone();
-		if let Some((input_node, id, input, path)) = self.nodes.iter_mut().filter(|(id, _)| !resolved_lookup.contains(id)).find_map(|(id, node)| {
+		if let Some((input_node, id, input, mut path)) = self.nodes.iter_mut().filter(|(id, _)| !resolved_lookup.contains(id)).find_map(|(id, node)| {
 			if let ProtoNodeInput::Node(input_node, false) = node.input {
 				resolved.insert(*id);
 				let pre_node_input = inputs.get(input_node as usize).expect("input node should exist");
@@ -288,6 +288,7 @@ impl ProtoNetwork {
 		}) {
 			lookup.insert(id, compose_node_id);
 			self.replace_node_references(&lookup, true);
+			path.push(id);
 			self.nodes.push((
 				compose_node_id,
 				ProtoNode {

node-graph/interpreted-executor/src/executor.rs

@@ -50,6 +50,10 @@ impl DynamicExecutor {
 		Ok(())
 	}
 
+	pub fn introspect(&self, node_path: &[NodeId]) -> Option<Option<String>> {
+		self.tree.introspect(node_path)
+	}
+
 	pub fn input_type(&self) -> Option<Type> {
 		self.typing_context.type_of(self.output).map(|node_io| node_io.input.clone())
 	}
@@ -99,6 +103,7 @@ impl NodeContainer<'static> {
 #[derive(Default, Debug, Clone)]
 pub struct BorrowTree {
 	nodes: HashMap<NodeId, Arc<RwLock<NodeContainer<'static>>>>,
+	source_map: HashMap<Vec<NodeId>, NodeId>,
 }
 
 impl BorrowTree {
@@ -123,6 +128,7 @@ impl BorrowTree {
 				node.reset();
 			}
 			old_nodes.remove(&id);
+			self.source_map.retain(|_, nid| *nid != id);
 		}
 		Ok(old_nodes.into_iter().collect())
 	}
@@ -139,6 +145,14 @@ impl BorrowTree {
 		node
 	}
 
+	pub fn introspect(&self, node_path: &[NodeId]) -> Option<Option<String>> {
+		let id = self.source_map.get(node_path)?;
+		let node = self.nodes.get(id)?;
+		let reader = node.read().unwrap();
+		let node = reader.node.as_ref();
+		Some(node.serialize())
+	}
+
 	pub fn get(&self, id: NodeId) -> Option<Arc<RwLock<NodeContainer<'static>>>> {
 		self.nodes.get(&id).cloned()
 	}
@@ -163,6 +177,7 @@ impl BorrowTree {
 
 	pub fn push_node(&mut self, id: NodeId, proto_node: ProtoNode, typing_context: &TypingContext) -> Result<(), String> {
 		let ProtoNode { construction_args, identifier, .. } = proto_node;
+		self.source_map.insert(proto_node.document_node_path, id);
 
 		match construction_args {
 			ConstructionArgs::Value(value) => {