Allow syntax tree to update when changing files

Previously when using the file based syntax tree, it would not update until a
change had been made in the new file. Now we automatically update the syntax
tree to match the current file.

editors/code/src/events/change_active_text_editor.ts

@@ -1,17 +1,25 @@
 import { TextEditor } from 'vscode';
 import { TextDocumentIdentifier } from 'vscode-languageclient';
 
+import {
+    SyntaxTreeContentProvider,
+    syntaxTreeUri
+} from '../commands/syntaxTree';
 import { Decoration } from '../highlighting';
 import { Server } from '../server';
 
-export async function handle(editor: TextEditor | undefined) {
+export function makeHandler(syntaxTreeProvider: SyntaxTreeContentProvider) {
-    if (
+    return async function handle(editor: TextEditor | undefined) {
-        !Server.config.highlightingOn ||
+        if (!editor || editor.document.languageId !== 'rust') {
-        !editor ||
-        editor.document.languageId !== 'rust'
-    ) {
             return;
         }
+
+        syntaxTreeProvider.eventEmitter.fire(syntaxTreeUri);
+
+        if (!Server.config.highlightingOn) {
+            return;
+        }
+
         const params: TextDocumentIdentifier = {
             uri: editor.document.uri.toString()
         };
@@ -20,4 +28,5 @@ export async function handle(editor: TextEditor | undefined) {
             params
         );
         Server.highlighter.setHighlights(editor, decorations);
+    };
 }

editors/code/src/extension.ts

@@ -94,13 +94,13 @@ export function activate(context: vscode.ExtensionContext) {
             notifications.publishDecorations.handle
         ]
     ];
+    const syntaxTreeContentProvider = new SyntaxTreeContentProvider();
 
     // The events below are plain old javascript events, triggered and handled by vscode
     vscode.window.onDidChangeActiveTextEditor(
-        events.changeActiveTextEditor.handle
+        events.changeActiveTextEditor.makeHandler(syntaxTreeContentProvider)
     );
 
-    const syntaxTreeContentProvider = new SyntaxTreeContentProvider();
     disposeOnDeactivation(
         vscode.workspace.registerTextDocumentContentProvider(
             'rust-analyzer',