Add support for variables in stack frames

dwds/lib/src/chrome_proxy_service.dart

@@ -567,6 +567,7 @@ const _stdoutTypes = ['log', 'info', 'warning'];
 /// result.
 void handleErrorIfPresent(WipResponse response,
     {String evalContents, Object additionalDetails}) {
+  if (response == null) return;
   if (response.result.containsKey('exceptionDetails')) {
     throw ChromeDebugException(
         response.result['exceptionDetails'] as Map<String, dynamic>,

dwds/lib/src/debugger.dart

@@ -11,6 +11,7 @@ import 'chrome_proxy_service.dart';
 import 'dart_uri.dart';
 import 'domain.dart';
 import 'location.dart';
+import 'objects.dart';
 import 'sources.dart';
 
 /// Converts from ExceptionPauseMode strings to [PauseState] enums.
@@ -146,12 +147,13 @@ class Debugger extends Domain {
     sources = Sources(_assetHandler);
     // We must add a listener before enabling the debugger otherwise we will
     // miss events.
-    _chromeDebugger.onScriptParsed.listen(sources.scriptParsed);
-    _chromeDebugger.onPaused.listen(_pauseHandler);
-    _chromeDebugger.onResumed.listen(_resumeHandler);
+    // Allow a null debugger/connection for unit tests.
+    _chromeDebugger?.onScriptParsed?.listen(sources.scriptParsed);
+    _chromeDebugger?.onPaused?.listen(_pauseHandler);
+    _chromeDebugger?.onResumed?.listen(_resumeHandler);
 
-    handleErrorIfPresent(await _tabConnection.page.enable() as WipResponse);
-    handleErrorIfPresent(await _chromeDebugger.enable() as WipResponse);
+    handleErrorIfPresent(await _tabConnection?.page?.enable() as WipResponse);
+    handleErrorIfPresent(await _chromeDebugger?.enable() as WipResponse);
   }
 
   /// Add a breakpoint at the given position.
@@ -268,10 +270,10 @@ class Debugger extends Domain {
 
   /// Translates Chrome callFrames contained in [DebuggerPausedEvent] into Dart
   /// [Frame]s.
-  List<Frame> _dartFramesFor(DebuggerPausedEvent e) {
+  Future<List<Frame>> dartFramesFor(List<Map<String, dynamic>> frames) async {
     var dartFrames = <Frame>[];
     var index = 0;
-    for (var frame in e.params['callFrames']) {
+    for (var frame in frames) {
       var location = frame['location'];
       var functionName = frame['functionName'] as String ?? '';
       functionName = functionName.split('.').last;
@@ -282,12 +284,52 @@ class Debugger extends Domain {
       if (dartFrame != null) {
         dartFrame.code.name = functionName.isEmpty ? '<closure>' : functionName;
         dartFrame.index = index++;
+        dartFrame.vars =
+            await _variablesFor(frame['scopeChain'] as List<dynamic>);
         dartFrames.add(dartFrame);
       }
     }
     return dartFrames;
   }
 
+  /// The variables visible in a frame in Dart protocol [BoundVariable] form.
+  Future<List<BoundVariable>> _variablesFor(List<dynamic> scopeChain) async {
+    // TODO: Much better logic for which frames to use. This is probably just
+    // the dynamically visible variables, so we should omit library scope.
+    return [
+      for (var scope in scopeChain.take(2)) ...await _boundVariables(scope)
+    ];
+  }
+
+  /// The [BoundVariable]s visible in a v8 'scope' object as found in the
+  /// 'scopeChain' field of the 'callFrames' in a DebuggerPausedEvent.
+  Future<Iterable<BoundVariable>> _boundVariables(dynamic scope) async {
+    var properties =
+        await _getProperties(scope['object']['objectId'] as String);
+    // We return one level of properties from this object. Sub-properties are
+    // another round trip.
+    var refs = properties
+        .map<Future<BoundVariable>>((property) async => BoundVariable()
+          ..name = property.name
+          ..value = await inspector.instanceRefFor(property.value));
+    return Future.wait(refs);
+  }
+
+  /// Calls the Chrome Runtime.getProperties API for the object
+  /// with [id].
+  Future<List<Property>> _getProperties(String id) async {
+    var response = await _tabConnection.runtime
+        .sendCommand('Runtime.getProperties', params: {
+      'objectId': id,
+      'ownProperties': true,
+    });
+    var jsProperties = response.result['result'];
+    var properties = (jsProperties as List)
+        .map<Property>((each) => Property(each as Map<String, dynamic>))
+        .toList();
+    return properties;
+  }
+
   /// Returns a Dart [Frame] for a [JsLocation].
   Frame _frameFor(JsLocation jsLocation) {
     // TODO(sdk/issues/37240) - ideally we look for an exact location instead
@@ -332,7 +374,9 @@ class Debugger extends Domain {
       }
       event.kind = EventKind.kPauseInterrupted;
     }
-    var frames = _dartFramesFor(e);
+    var jsFrames =
+        (e.params['callFrames'] as List).cast<Map<String, dynamic>>();
+    var frames = await dartFramesFor(jsFrames);
     _pausedStack = Stack()
       ..frames = frames
       ..messages = [];

dwds/lib/src/domain.dart

@@ -16,6 +16,10 @@ abstract class Domain {
 
   Domain(this._appInspectorProvider);
 
+  /// A constructor for the AppInspector to call which doesn't set
+  /// [_appInspectorProvider] as it's not used by the AppInspector.
+  Domain.forInspector() : _appInspectorProvider = null;
+
   AppInspector get inspector => _appInspectorProvider();
 
   /// Validate that isolateId matches the current isolate we're connected to and

dwds/lib/src/inspector.dart

@@ -2,21 +2,24 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.import 'dart:async';
 
+import 'dart:math' as math show min;
+
 import 'package:path/path.dart' as p;
 import 'package:vm_service_lib/vm_service_lib.dart';
 import 'package:webkit_inspection_protocol/webkit_inspection_protocol.dart';
 
 import 'chrome_proxy_service.dart';
 import 'dart_uri.dart';
 import 'debugger.dart';
+import 'domain.dart';
 import 'helpers.dart';
 
 /// An inspector for a running Dart application contained in the
 /// [WipConnection].
 ///
 /// Provides information about currently loaded scripts and objects and support
 /// for eval.
-class AppInspector {
+class AppInspector extends Domain {
   /// Map of class ID to [Class].
   final _classes = <String, Class>{};
 
@@ -50,7 +53,13 @@ class AppInspector {
     this._assetHandler,
     this._debugger,
     this._root,
-  ) : isolateRef = _toIsolateRef(isolate);
+  )   : isolateRef = _toIsolateRef(isolate),
+        super.forInspector();
+
+  @override
+
+  /// We are the inspector, so this getter is trivial.
+  AppInspector get inspector => this;
 
   Future<void> _initialize() async {
     isolate.libraries.addAll(await _getLibraryRefs());
@@ -146,9 +155,16 @@ function($argsString) {
             'scope': scope,
           });
     }
-    var remoteObject =
-        RemoteObject(result.result['result'] as Map<String, dynamic>);
+    return await instanceRefFor(
+        RemoteObject(result.result['result'] as Map<String, dynamic>));
+  }
 
+  /// Create an [InstanceRef] for the given Chrome [remoteObject].
+  Future<InstanceRef> instanceRefFor(RemoteObject remoteObject) async {
+    // If we have a null result, treat it as a reference to null.
+    if (remoteObject == null) {
+      return _primitiveInstance(InstanceKind.kNull, remoteObject);
+    }
     switch (remoteObject.type) {
       case 'string':
         return _primitiveInstance(InstanceKind.kString, remoteObject);
@@ -157,16 +173,27 @@ function($argsString) {
       case 'boolean':
         return _primitiveInstance(InstanceKind.kBool, remoteObject);
       case 'object':
+        // TODO: Actual toString()
+        var toString = 'Placeholder for toString() result';
+        // TODO: Make the truncation consistent with the VM.
+        var truncated = toString.substring(0, math.min(100, toString.length));
         return InstanceRef()
           ..kind = InstanceKind.kPlainInstance
           ..id = remoteObject.objectId
+          ..valueAsString = toString
+          ..valueAsStringIsTruncated = truncated.length != toString.length
           // TODO(jakemac): Create a real ClassRef, we need a way of looking
           // up the library for a given instance to create it though.
           // https://github.com/dart-lang/sdk/issues/36771.
           ..classRef = ClassRef();
       default:
-        throw UnsupportedError(
-            'Unsupported response type ${remoteObject.type}');
+        // Return unsupported types as a String placeholder for now.
+        var unsupported = RemoteObject({
+          'type': 'String',
+          'value':
+              'Unsupported type:${remoteObject.type} (${remoteObject.description})'
+        });
+        return _primitiveInstance(InstanceKind.kString, unsupported);
     }
   }
 
@@ -189,7 +216,6 @@ function($argsString) {
     if (clazz != null) return clazz;
     var scriptRef = _scriptRefs[objectId];
     if (scriptRef != null) return await _getScript(isolateId, scriptRef);
-
     throw UnsupportedError(
         'Only libraries and classes are supported for getObject');
   }
@@ -350,10 +376,7 @@ function($argsString) {
 
   /// Returns all scripts in the isolate.
   Future<List<ScriptRef>> scriptRefs(String isolateId) async {
-    if (isolateId != isolate.id) {
-      throw ArgumentError.value(
-          isolateId, 'isolateId', 'Unrecognized isolate id');
-    }
+    checkIsolate(isolateId);
     var scripts = <ScriptRef>[];
     for (var lib in isolate.libraries) {
       // We can't provide the source for `dart:` imports so ignore for now.

dwds/lib/src/objects.dart

@@ -0,0 +1,31 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.import 'dart:async';
+
+/// A library for WebKit mirror objects and support code. These probably should
+/// get migrated into webkit_inspection_protocol over time.
+
+import 'package:webkit_inspection_protocol/webkit_inspection_protocol.dart';
+
+/// Represents a property of an object.
+class Property {
+  final Map<String, dynamic> _map;
+
+  Property(this._map);
+
+  /// The remote object value in unwrapped form.
+  ///
+  /// Useful for getting access to properties of particular types of
+  /// RemoteObject.
+  Map<String, dynamic> get rawValue => _map['value'] as Map<String, dynamic>;
+
+  /// Remote object value in case of primitive values or JSON values (if it was
+  /// requested). (optional)
+  RemoteObject get value => RemoteObject(rawValue);
+
+  /// The name of the property
+  String get name => _map['name'] as String;
+
+  @override
+  String toString() => '$name $value';
+}

dwds/lib/src/sources.dart

@@ -69,17 +69,19 @@ class Sources {
             dartUri,
           );
           serverPaths.add(dartUri.serverPath);
-          _sourceToLocation
-              .putIfAbsent(dartUri.serverPath, () => Set())
-              .add(location);
-          _scriptIdToLocation
-              .putIfAbsent(script.scriptId, () => Set())
-              .add(location);
+          noteLocation(dartUri.serverPath, location, script.scriptId);
         }
       }
     }
   }
 
+  /// Add [location] to our lookups for both the Dart and JS scripts.
+  void noteLocation(
+      String dartServerPath, Location location, String wipScriptId) {
+    _sourceToLocation.putIfAbsent(dartServerPath, () => Set()).add(location);
+    _scriptIdToLocation.putIfAbsent(wipScriptId, () => Set()).add(location);
+  }
+
   /// Returns the tokenPosTable for the provided Dart script path as defined
   /// in:
   /// https://github.com/dart-lang/sdk/blob/master/runtime/vm/service/service.md#script