5 files changed, 75 insertions, 38 deletions

diff --git a/editors/code/package.json b/editors/code/package.json
index d4ce2ae2c..fda411810 100644
--- a/editors/code/package.json
+++ b/editors/code/package.json
@@ -75,7 +75,7 @@
         "commands": [
             {
                 "command": "rust-analyzer.syntaxTree",
-                "title": "Show syntax tree for current file",
+                "title": "Show Syntax Tree",
                 "category": "Rust Analyzer"
             },
             {
diff --git a/editors/code/src/commands/syntaxTree.ts b/editors/code/src/commands/syntaxTree.ts
index c0baf08c5..2f50fe14b 100644
--- a/editors/code/src/commands/syntaxTree.ts
+++ b/editors/code/src/commands/syntaxTree.ts
@@ -1,11 +1,11 @@
 import * as vscode from 'vscode';
-import { TextDocumentIdentifier } from 'vscode-languageclient';
+import { Range, TextDocumentIdentifier } from 'vscode-languageclient';
 
 import { Server } from '../server';
 
 export const syntaxTreeUri = vscode.Uri.parse('rust-analyzer://syntaxtree');
 
-export class TextDocumentContentProvider
+export class SyntaxTreeContentProvider
     implements vscode.TextDocumentContentProvider {
     public eventEmitter = new vscode.EventEmitter<vscode.Uri>();
     public syntaxTree: string = 'Not available';
@@ -17,8 +17,21 @@ export class TextDocumentContentProvider
         if (editor == null) {
             return '';
         }
+
+        let range: Range | undefined;
+
+        // When the range based query is enabled we take the range of the selection
+        if (uri.query === 'range=true') {
+            range = editor.selection.isEmpty
+                ? undefined
+                : Server.client.code2ProtocolConverter.asRange(
+                      editor.selection
+                  );
+        }
+
         const request: SyntaxTreeParams = {
-            textDocument: { uri: editor.document.uri.toString() }
+            textDocument: { uri: editor.document.uri.toString() },
+            range
         };
         return Server.client.sendRequest<SyntaxTreeResult>(
             'rust-analyzer/syntaxTree',
@@ -33,6 +46,7 @@ export class TextDocumentContentProvider
 
 interface SyntaxTreeParams {
     textDocument: TextDocumentIdentifier;
+    range?: Range;
 }
 
 type SyntaxTreeResult = string;
@@ -40,11 +54,23 @@ type SyntaxTreeResult = string;
 // Opens the virtual file that will show the syntax tree
 //
 // The contents of the file come from the `TextDocumentContentProvider`
-export async function handle() {
-    const document = await vscode.workspace.openTextDocument(syntaxTreeUri);
-    return vscode.window.showTextDocument(
-        document,
-        vscode.ViewColumn.Two,
-        true
-    );
+export function createHandle(provider: SyntaxTreeContentProvider) {
+    return async () => {
+        const editor = vscode.window.activeTextEditor;
+        const rangeEnabled = !!(editor && !editor.selection.isEmpty);
+
+        const uri = rangeEnabled
+            ? vscode.Uri.parse(`${syntaxTreeUri.toString()}?range=true`)
+            : syntaxTreeUri;
+
+        const document = await vscode.workspace.openTextDocument(uri);
+
+        provider.eventEmitter.fire(uri);
+
+        return vscode.window.showTextDocument(
+            document,
+            vscode.ViewColumn.Two,
+            true
+        );
+    };
 }
diff --git a/editors/code/src/events/change_active_text_editor.ts b/editors/code/src/events/change_active_text_editor.ts
index af295b2ec..64be56225 100644
--- a/editors/code/src/events/change_active_text_editor.ts
+++ b/editors/code/src/events/change_active_text_editor.ts
@@ -1,23 +1,32 @@
 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) {
-    if (
-        !Server.config.highlightingOn ||
-        !editor ||
-        editor.document.languageId !== 'rust'
-    ) {
-        return;
-    }
-    const params: TextDocumentIdentifier = {
-        uri: editor.document.uri.toString()
+export function makeHandler(syntaxTreeProvider: SyntaxTreeContentProvider) {
+    return async function handle(editor: TextEditor | undefined) {
+        if (!editor || editor.document.languageId !== 'rust') {
+            return;
+        }
+
+        syntaxTreeProvider.eventEmitter.fire(syntaxTreeUri);
+
+        if (!Server.config.highlightingOn) {
+            return;
+        }
+
+        const params: TextDocumentIdentifier = {
+            uri: editor.document.uri.toString()
+        };
+        const decorations = await Server.client.sendRequest<Decoration[]>(
+            'rust-analyzer/decorationsRequest',
+            params
+        );
+        Server.highlighter.setHighlights(editor, decorations);
     };
-    const decorations = await Server.client.sendRequest<Decoration[]>(
-        'rust-analyzer/decorationsRequest',
-        params
-    );
-    Server.highlighter.setHighlights(editor, decorations);
 }
diff --git a/editors/code/src/events/change_text_document.ts b/editors/code/src/events/change_text_document.ts
index 6be057245..89488bc61 100644
--- a/editors/code/src/events/change_text_document.ts
+++ b/editors/code/src/events/change_text_document.ts
@@ -1,20 +1,18 @@
 import * as vscode from 'vscode';
 
 import {
-    syntaxTreeUri,
-    TextDocumentContentProvider
+    SyntaxTreeContentProvider,
+    syntaxTreeUri
 } from '../commands/syntaxTree';
 
-export function createHandler(
-    textDocumentContentProvider: TextDocumentContentProvider
-) {
+export function createHandler(syntaxTreeProvider: SyntaxTreeContentProvider) {
     return (event: vscode.TextDocumentChangeEvent) => {
         const doc = event.document;
         if (doc.languageId !== 'rust') {
             return;
         }
         afterLs(() => {
-            textDocumentContentProvider.eventEmitter.fire(syntaxTreeUri);
+            syntaxTreeProvider.eventEmitter.fire(syntaxTreeUri);
         });
     };
 }
diff --git a/editors/code/src/extension.ts b/editors/code/src/extension.ts
index 8b332eeb2..941beba18 100644
--- a/editors/code/src/extension.ts
+++ b/editors/code/src/extension.ts
@@ -2,7 +2,7 @@ import * as vscode from 'vscode';
 import * as lc from 'vscode-languageclient';
 
 import * as commands from './commands';
-import { TextDocumentContentProvider } from './commands/syntaxTree';
+import { SyntaxTreeContentProvider } from './commands/syntaxTree';
 import * as events from './events';
 import * as notifications from './notifications';
 import { Server } from './server';
@@ -52,7 +52,6 @@ export function activate(context: vscode.ExtensionContext) {
     registerCommand('rust-analyzer.collectGarbage', () =>
         Server.client.sendRequest<null>('rust-analyzer/collectGarbage', null)
     );
-    registerCommand('rust-analyzer.syntaxTree', commands.syntaxTree.handle);
     registerCommand(
         'rust-analyzer.extendSelection',
         commands.extendSelection.handle
@@ -95,22 +94,27 @@ 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 textDocumentContentProvider = new TextDocumentContentProvider();
     disposeOnDeactivation(
         vscode.workspace.registerTextDocumentContentProvider(
             'rust-analyzer',
-            textDocumentContentProvider
+            syntaxTreeContentProvider
         )
     );
 
+    registerCommand(
+        'rust-analyzer.syntaxTree',
+        commands.syntaxTree.createHandle(syntaxTreeContentProvider)
+    );
+
     vscode.workspace.onDidChangeTextDocument(
-        events.changeTextDocument.createHandler(textDocumentContentProvider),
+        events.changeTextDocument.createHandler(syntaxTreeContentProvider),
         null,
         context.subscriptions
     );