implement a type hierarchy command

package.json

@@ -92,6 +92,12 @@
 				"key": "ctrl+alt+o",
 				"mac": "cmd+alt+o",
 				"when": "editorLangId == dart"
+			},
+			{
+				"command": "dart.showTypeHierarchy",
+				"key": "f4",
+				"mac": "f4",
+				"when": "editorLangId == dart"
 			}
 		],
 		"menus": {

src/commands/type_hierarchy.ts

@@ -0,0 +1,131 @@
+"use strict";
+
+import * as editors from "../editors";
+import * as vs from "vscode";
+import * as as from "../analysis/analysis_server_types";
+import { Analyzer } from "../analysis/analyzer";
+import { toRange } from "../utils";
+
+export class TypeHierarchyCommand implements vs.Disposable {
+	private context: vs.ExtensionContext;
+	private analyzer: Analyzer;
+	private commands: Array<vs.Disposable> = [];
+
+	constructor(context: vs.ExtensionContext, analyzer: Analyzer) {
+		this.context = context;
+		this.analyzer = analyzer;
+
+		this.commands.push(
+			vs.commands.registerTextEditorCommand("dart.showTypeHierarchy", this.showTypeHierarchy, this)
+		);
+	}
+
+	private showTypeHierarchy(editor: vs.TextEditor, editBuilder: vs.TextEditorEdit) {
+		if (!editors.hasActiveDartEditor()) {
+			vs.window.showWarningMessage("No active Dart editor.");
+			return;
+		}
+
+		let document = editor.document;
+
+		this.analyzer.searchGetTypeHierarchy({
+			file: document.fileName,
+			offset: document.offsetAt(editor.selection.active)
+		}).then(response => {
+			let items = response.hierarchyItems;
+			if (!items) {
+				vs.window.showInformationMessage('Type hierarchy not available.');
+				return;
+			}
+
+			let options = { placeHolder: name(items, 0) };
+
+			// TODO: How / where to show implements?
+			// TODO: How / where to show mixins?
+			let tree = [];
+			let startItem = items[0];
+
+			tree.push(startItem);
+			addParents(items, tree, startItem);
+			addChildren(items, tree, startItem);
+
+			vs.window.showQuickPick(tree.map(item => itemToPick(item, items)), options).then(result => {
+				if (result) {
+					let location: as.Location = result['location'];
+					vs.workspace.openTextDocument(location.file).then(document => {
+						vs.window.showTextDocument(document).then(editor => {
+							let range = toRange(location);
+							editor.revealRange(range, vs.TextEditorRevealType.InCenterIfOutsideViewport);
+							editor.selection = new vs.Selection(range.end, range.start);
+						});
+					});
+				}
+			});
+		});
+	}
+
+	dispose(): any {
+		for (let command of this.commands)
+			command.dispose();
+	}
+}
+
+function addParents(items: as.TypeHierarchyItem[], tree: as.TypeHierarchyItem[], item: as.TypeHierarchyItem) {
+	if (item.superclass) {
+		let parent = items[item.superclass];
+		tree.unshift(parent);
+		addParents(items, tree, parent);
+	}
+}
+
+function addChildren(items: as.TypeHierarchyItem[], tree: as.TypeHierarchyItem[], item: as.TypeHierarchyItem) {
+	// Handle direct children.
+	for (let index of item.subclasses) {
+		let child = items[index];
+		tree.push(child);
+	}
+
+	// Handle grandchildren.
+	for (let index of item.subclasses) {
+		let child = items[index];
+		if (child.subclasses.length > 0)
+			addChildren(items, tree, child);
+	}
+}
+
+function itemToPick(item: as.TypeHierarchyItem, items: as.TypeHierarchyItem[]): vs.QuickPickItem {
+	let desc = '';
+
+	// extends
+	if (item.superclass !== undefined && name(items, item.superclass) != 'Object')
+		desc += `extends ${name(items, item.superclass)}`;
+
+	// implements
+	if (item.interfaces.length > 0) {
+		if (desc.length > 0)
+			desc += ', ';
+		desc += `implements ${item.interfaces.map(i => name(items, i)).join(', ')}`;
+	}
+
+	// with
+	if (item.mixins.length > 0) {
+		if (desc.length > 0)
+			desc += ', ';
+		desc += `with ${item.mixins.map(i => name(items, i)).join(', ')}`;
+	}
+
+	// TODO: Show the library location in the details (dart:core, ...) (share code
+	// with dart_workspace_symbol_provider.ts).
+
+	let result = {
+		label: item.classElement.name,
+		description: desc,
+		location: item.classElement.location
+	};
+
+	return result;
+}
+
+function name(items: as.TypeHierarchyItem[], index: number) {
+	return items[index].classElement.name;
+}

src/extension.ts

@@ -24,6 +24,7 @@ import { DartRenameProvider } from "./providers/dart_rename_provider";
 import { FileChangeHandler } from "./file_change_handler";
 import { OpenFileTracker } from "./open_file_tracker";
 import { SdkCommands } from "./commands/sdk";
+import { TypeHierarchyCommand } from "./commands/type_hierarchy";
 import { ServerStatusNotification } from "./analysis/analysis_server_types";
 
 const DART_MODE: vs.DocumentFilter = { language: "dart", scheme: "file" };
@@ -132,6 +133,9 @@ export function activate(context: vs.ExtensionContext) {
 
 	// Set up commands for Dart editors.
 	context.subscriptions.push(new EditCommands(context, analyzer));
+
+	// Register misc commands.
+ 	context.subscriptions.push(new TypeHierarchyCommand(context, analyzer));
 }
 
 function handleConfigurationChange() {