dwds/lib/src/debugger.dart - webdev - Git at Google

 // 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';

 import 'dart:async';

 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 'helpers.dart';
 import 'location.dart';
 import 'sources.dart';

 /// Converts from ExceptionPauseMode strings to [PauseState] enums.
 ///
 /// Values defined in:
 /// https://chromedevtools.github.io/devtools-protocol/tot/Debugger#method-setPauseOnExceptions
 const _pauseModePauseStates = {
   'none': PauseState.none,
   'all': PauseState.all,
   'unhandled': PauseState.uncaught,
 };

 class Debugger {
   WipConnection _tabConnection;

   final AssetHandler _assetHandler;
   final StreamNotify _streamNotify;
   final AppInspectorProvider _appInspectorProvider;

   /// The root URI from which the application is served.
   final String _root;

   Debugger._(
     this._assetHandler,
     this._tabConnection,
     this._streamNotify,
     this._appInspectorProvider,
     // TODO(401) - Remove.
     this._root,
   ) : _breakpoints = _Breakpoints(_appInspectorProvider);

   WipDebugger get _chromeDebugger => _tabConnection.debugger;

   /// The scripts and sourcemaps for the application, both JS and Dart.
   Sources sources;

   /// The breakpoints we have set so far, indexable by either
   /// Dart or JS ID.
   _Breakpoints _breakpoints;

   /// Allocates Dart breakpoint IDs
   int _nextBreakpointId = 1;

   Stack _pausedStack;

   bool _isStepping = false;

   Future<Success> pause() async {
     _isStepping = false;
     var result = await _chromeDebugger.sendCommand('Debugger.pause');
     handleErrorIfPresent(result);
     return Success();
   }

   Future<Success> setExceptionPauseMode(String isolateId, String mode) async {
     if (isolateId != _appInspectorProvider().isolate?.id) {
       throw ArgumentError.value(
           isolateId, 'isolateId', 'Unrecognized isolate id');
     }
     var pauseState = _pauseModePauseStates[mode.toLowerCase()] ??
         (throw ArgumentError.value('mode', 'Unsupported mode `$mode`'));
     await _chromeDebugger.setPauseOnExceptions(pauseState);
     return Success();
   }

   /// Resumes the debugger.
   ///
   /// Step parameter options:
   /// https://github.com/dart-lang/sdk/blob/master/runtime/vm/service/service.md#resume
   ///
   /// If the step parameter is not provided, the program will resume regular
   /// execution.
   ///
   /// If the step parameter is provided, it indicates what form of
   /// single-stepping to use.
   ///
   /// Note that stepping will automatically continue until Chrome is paused at
   /// a location for which we have source information.
   Future<Success> resume(String isolateId,
       {String step, int frameIndex}) async {
     if (isolateId != _appInspectorProvider().isolate?.id) {
       throw ArgumentError.value(
           isolateId, 'isolateId', 'Unrecognized isolate id');
     }
     if (frameIndex != null) {
       throw ArgumentError('FrameIndex is currently unsupported.');
     }
     WipResponse result;
     if (step != null) {
       _isStepping = true;
       switch (step) {
         case 'Over':
           result = await _chromeDebugger.sendCommand('Debugger.stepOver');
           break;
         case 'Out':
           result = await _chromeDebugger.sendCommand('Debugger.stepOut');
           break;
         case 'Into':
           result = await _chromeDebugger.sendCommand('Debugger.stepInto');
           break;
         default:
           throw ArgumentError('Unexpected value for step: $step');
       }
     } else {
       _isStepping = false;
       result = await _chromeDebugger.sendCommand('Debugger.resume');
     }
     handleErrorIfPresent(result);
     return Success();
   }

   /// Returns the current Dart stack for the paused debugger.
   ///
   /// Returns null if the debugger is not paused.
   Future<Stack> getStack(String isolateId) async {
     if (isolateId != _appInspectorProvider().isolate?.id) {
       throw ArgumentError.value(
           isolateId, 'isolateId', 'Unrecognized isolate id');
     }
     return _pausedStack;
   }

   static Future<Debugger> create(
       AssetHandler assetHandler,
       WipConnection tabConnection,
       StreamNotify streamNotify,
       AppInspectorProvider appInspectorProvider,
       String root) async {
     var debugger = Debugger._(
       assetHandler,
       tabConnection,
       streamNotify,
       appInspectorProvider,
       // TODO(401) - Remove.
       root,
     );
     await debugger._initialize();
     return debugger;
   }

   Future<Null> _initialize() async {
     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);

     handleErrorIfPresent(await _tabConnection.page.enable() as WipResponse);
     handleErrorIfPresent(await _chromeDebugger.enable() as WipResponse);
   }

   /// Add a breakpoint at the given position.
   ///
   /// Note that line and column are Dart source locations and one-based.
   Future<Breakpoint> addBreakpoint(String isolateId, String scriptId, int line,
       {int column}) async {
     var inspector = _appInspectorProvider();
     var isolate = inspector.isolate;
     if (isolateId != isolate.id) {
       throw ArgumentError.value(
           isolateId, 'isolateId', 'Unrecognized isolate id');
     }

     var dartScript = await inspector.scriptWithId(scriptId);
     // TODO(401): Remove the additional parameter.
     var dartUri =
         DartUri(dartScript.uri, '${Uri.parse(_root).path}/garbage.dart');
     var location = _locationForDart(dartUri, line);
     // TODO: Handle cases where a breakpoint can't be set exactly at that line.
     if (location == null) return null;
     var jsBreakpointId = await _setBreakpoint(location);
     var dartBreakpoint = _dartBreakpoint(dartScript, location, isolate);
     _breakpoints.noteBreakpoint(js: jsBreakpointId, bp: dartBreakpoint);
     return dartBreakpoint;
   }

   /// Create a Dart breakpoint at [location] in [dartScript].
   Breakpoint _dartBreakpoint(
       ScriptRef dartScript, Location location, Isolate isolate) {
     var breakpoint = Breakpoint()
       ..resolved = true
       ..id = '${_nextBreakpointId++}'
       ..location = (SourceLocation()
         ..script = dartScript
         ..tokenPos = location.tokenPos);
     _streamNotify(
         'Debug',
         Event()
           ..kind = EventKind.kBreakpointAdded
           ..isolate = toIsolateRef(isolate)
           ..breakpoint = breakpoint);
     return breakpoint;
   }

   /// Remove a Dart breakpoint.
   Future<Success> removeBreakpoint(
       String isolateId, String breakpointId) async {
     var isolate = _appInspectorProvider().isolate;
     if (isolateId != isolate.id) {
       throw ArgumentError.value(
           isolateId, 'isolateId', 'Unrecognized isolate id');
     }
     if (breakpointId == null) {
       throw ArgumentError.notNull('breakpointId');
     }
     var jsId = _breakpoints.jsId(breakpointId);
     var bp = _breakpoints.removeBreakpoint(js: jsId, dartId: breakpointId);
     if (bp == null) {
       throw ArgumentError.value(
           breakpointId, 'Breakpoint not found with this id.');
     }
     _streamNotify(
         'Debug',
         Event()
           ..kind = EventKind.kBreakpointRemoved
           ..isolate = toIsolateRef(isolate)
           ..breakpoint = bp);
     await _removeBreakpoint(jsId);
     return Success();
   }

   /// Call the Chrome protocol setBreakpoint and return the breakpoint ID.
   Future<String> _setBreakpoint(Location location) async {
     // Location is 0 based according to:
     // https://chromedevtools.github.io/devtools-protocol/tot/Debugger#type-Location
     var response =
         await _chromeDebugger.sendCommand('Debugger.setBreakpoint', params: {
       'location': {
         'scriptId': location.jsLocation.scriptId,
         'lineNumber': location.jsLocation.line - 1,
       }
     });
     handleErrorIfPresent(response);
     return response.result['breakpointId'] as String;
   }

   /// Call the Chrome protocol removeBreakpoint.
   Future<void> _removeBreakpoint(String breakpointId) async {
     var response = await _chromeDebugger.sendCommand(
         'Debugger.removeBreakpoint',
         params: {'breakpointId': breakpointId});
     handleErrorIfPresent(response);
   }

   /// Find the [Location] for the given Dart source position.
   ///
   /// The [line] number is 1-based.
   Location _locationForDart(DartUri uri, int line) => sources
       .locationsForDart(uri.serverPath)
       .firstWhere((location) => location.dartLocation.line == line,
           orElse: () => null);

   /// Find the [Location] for the given JS source position.
   ///
   /// The [line] and [column] are 1-based.
   Location _locationForJs(String scriptId, int line, int column) =>
       sources.locationsForJs(scriptId).firstWhere(
           (location) =>
               location.jsLocation.line == line &&
               location.jsLocation.column == column,
           orElse: () => null);

   /// Returns source [Location] for the paused event.
   ///
   /// If we do not have [Location] data for the embedded JS location, null is
   /// returned.
   Location _sourceLocation(DebuggerPausedEvent e) {
     var frame = e.params['callFrames'][0];
     var location = frame['location'];
     var jsLocation = JsLocation.fromZeroBased(location['scriptId'] as String,
         location['lineNumber'] as int, location['columnNumber'] as int);
     return _locationForJs(
         jsLocation.scriptId, jsLocation.line, jsLocation.column);
   }

   /// Translates Chrome callFrames contained in [DebuggerPausedEvent] into Dart
   /// [Frame]s.
   List<Frame> _dartFramesFor(DebuggerPausedEvent e) {
     var dartFrames = <Frame>[];
     var index = 0;
     for (var frame in e.params['callFrames']) {
       var location = frame['location'];
       var functionName = frame['functionName'] as String ?? '';
       functionName = functionName.split('.').last;
       // Chrome is 0 based. Account for this.
       var jsLocation = JsLocation.fromZeroBased(location['scriptId'] as String,
           location['lineNumber'] as int, location['columnNumber'] as int);
       var dartFrame = _frameFor(jsLocation);
       if (dartFrame != null) {
         dartFrame.code.name = functionName.isEmpty ? '<closure>' : functionName;
         dartFrame.index = index++;
         dartFrames.add(dartFrame);
       }
     }
     return dartFrames;
   }

   /// Returns a Dart [Frame] for a [JsLocation].
   Frame _frameFor(JsLocation jsLocation) {
     // TODO(sdk/issues/37240) - ideally we look for an exact location instead
     // of the closest location on a given line.
     Location bestLocation;
     for (var location in sources.locationsForJs(jsLocation.scriptId)) {
       if (location.jsLocation.line == jsLocation.line) {
         bestLocation ??= location;
         if ((location.jsLocation.column - jsLocation.column).abs() <
             (bestLocation.jsLocation.column - jsLocation.column).abs()) {
           bestLocation = location;
         }
       }
     }
     if (bestLocation == null) return null;
     var script = _appInspectorProvider()
         ?.scriptRefFor(bestLocation.dartLocation.uri.serverPath);
     return Frame()
       ..code = (CodeRef()..kind = CodeKind.kDart)
       ..location = (SourceLocation()
         ..tokenPos = bestLocation.tokenPos
         ..script = script)
       ..kind = FrameKind.kRegular;
   }

   /// Handles pause events coming from the Chrome connection.
   Future<void> _pauseHandler(DebuggerPausedEvent e) async {
     var isolate = _appInspectorProvider().isolate;
     if (isolate == null) return;
     var event = Event()..isolate = toIsolateRef(isolate);
     var params = e.params;
     var breakpoints = params['hitBreakpoints'] as List;
     if (breakpoints.isNotEmpty) {
       event.kind = EventKind.kPauseBreakpoint;
     } else if (e.reason == 'exception' || e.reason == 'assert') {
       event.kind = EventKind.kPauseException;
     } else {
       // If we don't have source location continue stepping.
       if (_isStepping && _sourceLocation(e) == null) {
         await _chromeDebugger.sendCommand('Debugger.stepInto');
         return;
       }
       event.kind = EventKind.kPauseInterrupted;
     }
     var frames = _dartFramesFor(e);
     _pausedStack = Stack()
       ..frames = frames
       ..messages = [];
     if (frames.isNotEmpty) event.topFrame = frames.first;
     _streamNotify('Debug', event);
   }

   /// Handles resume events coming from the Chrome connection.
   Future<void> _resumeHandler(DebuggerResumedEvent e) async {
     // We can receive a resume event in the middle of a reload which will
     // result in a null isolate.
     var isolate = _appInspectorProvider()?.isolate;
     if (isolate == null) return;
     _pausedStack = null;
     _streamNotify(
         'Debug',
         Event()
           ..kind = EventKind.kResume
           ..isolate = toIsolateRef(isolate));
   }
 }

 /// Keeps track of the Dart and JS breakpoint Ids that correspond.
 class _Breakpoints {
   final Map<String, String> _byJsId = {};
   final Map<String, String> _byDartId = {};

   final AppInspectorProvider _appInspectorProvider;

   _Breakpoints(this._appInspectorProvider);

   /// Record the breakpoint.
   ///
   /// Either [dartId] or the Dart breakpoint [bp] must be provided.
   void noteBreakpoint({String js, String dartId, Breakpoint bp}) {
     _byJsId[js] = dartId ?? bp?.id;
     _byDartId[dartId ?? bp?.id] = js;
     var isolate = _appInspectorProvider().isolate;
     if (bp != null) {
       isolate?.breakpoints?.add(bp);
     }
   }

   Breakpoint removeBreakpoint({String js, String dartId, Breakpoint bp}) {
     var isolate = _appInspectorProvider().isolate;
     _byJsId.remove(js);
     _byDartId.remove(dartId ?? bp?.id);
     Breakpoint dartBp;
     // TODO: Do something better than the default throw when it's not found.
     dartBp = bp ??
         isolate.breakpoints
             .firstWhere((b) => b.id == dartId, orElse: () => null);
     isolate?.breakpoints?.remove(dartBp);
     return dartBp;
   }

   String dartId(String jsId) => _byJsId[jsId];

   String jsId(String dartId) => _byDartId[dartId];
 }
	// 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';

	import 'dart:async';

	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 'helpers.dart';
	import 'location.dart';
	import 'sources.dart';

	/// Converts from ExceptionPauseMode strings to [PauseState] enums.
	///
	/// Values defined in:
	/// https://chromedevtools.github.io/devtools-protocol/tot/Debugger#method-setPauseOnExceptions
	const _pauseModePauseStates = {
	'none': PauseState.none,
	'all': PauseState.all,
	'unhandled': PauseState.uncaught,
	};

	class Debugger {
	WipConnection _tabConnection;

	final AssetHandler _assetHandler;
	final StreamNotify _streamNotify;
	final AppInspectorProvider _appInspectorProvider;

	/// The root URI from which the application is served.
	final String _root;

	Debugger._(
	this._assetHandler,
	this._tabConnection,
	this._streamNotify,
	this._appInspectorProvider,
	// TODO(401) - Remove.
	this._root,
	) : _breakpoints = _Breakpoints(_appInspectorProvider);

	WipDebugger get _chromeDebugger => _tabConnection.debugger;

	/// The scripts and sourcemaps for the application, both JS and Dart.
	Sources sources;

	/// The breakpoints we have set so far, indexable by either
	/// Dart or JS ID.
	_Breakpoints _breakpoints;

	/// Allocates Dart breakpoint IDs
	int _nextBreakpointId = 1;

	Stack _pausedStack;

	bool _isStepping = false;

	Future<Success> pause() async {
	_isStepping = false;
	var result = await _chromeDebugger.sendCommand('Debugger.pause');
	handleErrorIfPresent(result);
	return Success();
	}

	Future<Success> setExceptionPauseMode(String isolateId, String mode) async {
	if (isolateId != _appInspectorProvider().isolate?.id) {
	throw ArgumentError.value(
	isolateId, 'isolateId', 'Unrecognized isolate id');
	}
	var pauseState = _pauseModePauseStates[mode.toLowerCase()] ??
	(throw ArgumentError.value('mode', 'Unsupported mode `$mode`'));
	await _chromeDebugger.setPauseOnExceptions(pauseState);
	return Success();
	}

	/// Resumes the debugger.
	///
	/// Step parameter options:
	/// https://github.com/dart-lang/sdk/blob/master/runtime/vm/service/service.md#resume
	///
	/// If the step parameter is not provided, the program will resume regular
	/// execution.
	///
	/// If the step parameter is provided, it indicates what form of
	/// single-stepping to use.
	///
	/// Note that stepping will automatically continue until Chrome is paused at
	/// a location for which we have source information.
	Future<Success> resume(String isolateId,
	{String step, int frameIndex}) async {
	if (isolateId != _appInspectorProvider().isolate?.id) {
	throw ArgumentError.value(
	isolateId, 'isolateId', 'Unrecognized isolate id');
	}
	if (frameIndex != null) {
	throw ArgumentError('FrameIndex is currently unsupported.');
	}
	WipResponse result;
	if (step != null) {
	_isStepping = true;
	switch (step) {
	case 'Over':
	result = await _chromeDebugger.sendCommand('Debugger.stepOver');
	break;
	case 'Out':
	result = await _chromeDebugger.sendCommand('Debugger.stepOut');
	break;
	case 'Into':
	result = await _chromeDebugger.sendCommand('Debugger.stepInto');
	break;
	default:
	throw ArgumentError('Unexpected value for step: $step');
	}
	} else {
	_isStepping = false;
	result = await _chromeDebugger.sendCommand('Debugger.resume');
	}
	handleErrorIfPresent(result);
	return Success();
	}

	/// Returns the current Dart stack for the paused debugger.
	///
	/// Returns null if the debugger is not paused.
	Future<Stack> getStack(String isolateId) async {
	if (isolateId != _appInspectorProvider().isolate?.id) {
	throw ArgumentError.value(
	isolateId, 'isolateId', 'Unrecognized isolate id');
	}
	return _pausedStack;
	}

	static Future<Debugger> create(
	AssetHandler assetHandler,
	WipConnection tabConnection,
	StreamNotify streamNotify,
	AppInspectorProvider appInspectorProvider,
	String root) async {
	var debugger = Debugger._(
	assetHandler,
	tabConnection,
	streamNotify,
	appInspectorProvider,
	// TODO(401) - Remove.
	root,
	);
	await debugger._initialize();
	return debugger;
	}

	Future<Null> _initialize() async {
	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);

	handleErrorIfPresent(await _tabConnection.page.enable() as WipResponse);
	handleErrorIfPresent(await _chromeDebugger.enable() as WipResponse);
	}

	/// Add a breakpoint at the given position.
	///
	/// Note that line and column are Dart source locations and one-based.
	Future<Breakpoint> addBreakpoint(String isolateId, String scriptId, int line,
	{int column}) async {
	var inspector = _appInspectorProvider();
	var isolate = inspector.isolate;
	if (isolateId != isolate.id) {
	throw ArgumentError.value(
	isolateId, 'isolateId', 'Unrecognized isolate id');
	}

	var dartScript = await inspector.scriptWithId(scriptId);
	// TODO(401): Remove the additional parameter.
	var dartUri =
	DartUri(dartScript.uri, '${Uri.parse(_root).path}/garbage.dart');
	var location = _locationForDart(dartUri, line);
	// TODO: Handle cases where a breakpoint can't be set exactly at that line.
	if (location == null) return null;
	var jsBreakpointId = await _setBreakpoint(location);
	var dartBreakpoint = _dartBreakpoint(dartScript, location, isolate);
	_breakpoints.noteBreakpoint(js: jsBreakpointId, bp: dartBreakpoint);
	return dartBreakpoint;
	}

	/// Create a Dart breakpoint at [location] in [dartScript].
	Breakpoint _dartBreakpoint(
	ScriptRef dartScript, Location location, Isolate isolate) {
	var breakpoint = Breakpoint()
	..resolved = true
	..id = '${_nextBreakpointId++}'
	..location = (SourceLocation()
	..script = dartScript
	..tokenPos = location.tokenPos);
	_streamNotify(
	'Debug',
	Event()
	..kind = EventKind.kBreakpointAdded
	..isolate = toIsolateRef(isolate)
	..breakpoint = breakpoint);
	return breakpoint;
	}

	/// Remove a Dart breakpoint.
	Future<Success> removeBreakpoint(
	String isolateId, String breakpointId) async {
	var isolate = _appInspectorProvider().isolate;
	if (isolateId != isolate.id) {
	throw ArgumentError.value(
	isolateId, 'isolateId', 'Unrecognized isolate id');
	}
	if (breakpointId == null) {
	throw ArgumentError.notNull('breakpointId');
	}
	var jsId = _breakpoints.jsId(breakpointId);
	var bp = _breakpoints.removeBreakpoint(js: jsId, dartId: breakpointId);
	if (bp == null) {
	throw ArgumentError.value(
	breakpointId, 'Breakpoint not found with this id.');
	}
	_streamNotify(
	'Debug',
	Event()
	..kind = EventKind.kBreakpointRemoved
	..isolate = toIsolateRef(isolate)
	..breakpoint = bp);
	await _removeBreakpoint(jsId);
	return Success();
	}

	/// Call the Chrome protocol setBreakpoint and return the breakpoint ID.
	Future<String> _setBreakpoint(Location location) async {
	// Location is 0 based according to:
	// https://chromedevtools.github.io/devtools-protocol/tot/Debugger#type-Location
	var response =
	await _chromeDebugger.sendCommand('Debugger.setBreakpoint', params: {
	'location': {
	'scriptId': location.jsLocation.scriptId,
	'lineNumber': location.jsLocation.line - 1,
	}
	});
	handleErrorIfPresent(response);
	return response.result['breakpointId'] as String;
	}

	/// Call the Chrome protocol removeBreakpoint.
	Future<void> _removeBreakpoint(String breakpointId) async {
	var response = await _chromeDebugger.sendCommand(
	'Debugger.removeBreakpoint',
	params: {'breakpointId': breakpointId});
	handleErrorIfPresent(response);
	}

	/// Find the [Location] for the given Dart source position.
	///
	/// The [line] number is 1-based.
	Location _locationForDart(DartUri uri, int line) => sources
	.locationsForDart(uri.serverPath)
	.firstWhere((location) => location.dartLocation.line == line,
	orElse: () => null);

	/// Find the [Location] for the given JS source position.
	///
	/// The [line] and [column] are 1-based.
	Location _locationForJs(String scriptId, int line, int column) =>
	sources.locationsForJs(scriptId).firstWhere(
	(location) =>
	location.jsLocation.line == line &&
	location.jsLocation.column == column,
	orElse: () => null);

	/// Returns source [Location] for the paused event.
	///
	/// If we do not have [Location] data for the embedded JS location, null is
	/// returned.
	Location _sourceLocation(DebuggerPausedEvent e) {
	var frame = e.params['callFrames'][0];
	var location = frame['location'];
	var jsLocation = JsLocation.fromZeroBased(location['scriptId'] as String,
	location['lineNumber'] as int, location['columnNumber'] as int);
	return _locationForJs(
	jsLocation.scriptId, jsLocation.line, jsLocation.column);
	}

	/// Translates Chrome callFrames contained in [DebuggerPausedEvent] into Dart
	/// [Frame]s.
	List<Frame> _dartFramesFor(DebuggerPausedEvent e) {
	var dartFrames = <Frame>[];
	var index = 0;
	for (var frame in e.params['callFrames']) {
	var location = frame['location'];
	var functionName = frame['functionName'] as String ?? '';
	functionName = functionName.split('.').last;
	// Chrome is 0 based. Account for this.
	var jsLocation = JsLocation.fromZeroBased(location['scriptId'] as String,
	location['lineNumber'] as int, location['columnNumber'] as int);
	var dartFrame = _frameFor(jsLocation);
	if (dartFrame != null) {
	dartFrame.code.name = functionName.isEmpty ? '<closure>' : functionName;
	dartFrame.index = index++;
	dartFrames.add(dartFrame);
	}
	}
	return dartFrames;
	}

	/// Returns a Dart [Frame] for a [JsLocation].
	Frame _frameFor(JsLocation jsLocation) {
	// TODO(sdk/issues/37240) - ideally we look for an exact location instead
	// of the closest location on a given line.
	Location bestLocation;
	for (var location in sources.locationsForJs(jsLocation.scriptId)) {
	if (location.jsLocation.line == jsLocation.line) {
	bestLocation ??= location;
	if ((location.jsLocation.column - jsLocation.column).abs() <
	(bestLocation.jsLocation.column - jsLocation.column).abs()) {
	bestLocation = location;
	}
	}
	}
	if (bestLocation == null) return null;
	var script = _appInspectorProvider()
	?.scriptRefFor(bestLocation.dartLocation.uri.serverPath);
	return Frame()
	..code = (CodeRef()..kind = CodeKind.kDart)
	..location = (SourceLocation()
	..tokenPos = bestLocation.tokenPos
	..script = script)
	..kind = FrameKind.kRegular;
	}

	/// Handles pause events coming from the Chrome connection.
	Future<void> _pauseHandler(DebuggerPausedEvent e) async {
	var isolate = _appInspectorProvider().isolate;
	if (isolate == null) return;
	var event = Event()..isolate = toIsolateRef(isolate);
	var params = e.params;
	var breakpoints = params['hitBreakpoints'] as List;
	if (breakpoints.isNotEmpty) {
	event.kind = EventKind.kPauseBreakpoint;
	} else if (e.reason == 'exception' \|\| e.reason == 'assert') {
	event.kind = EventKind.kPauseException;
	} else {
	// If we don't have source location continue stepping.
	if (_isStepping && _sourceLocation(e) == null) {
	await _chromeDebugger.sendCommand('Debugger.stepInto');
	return;
	}
	event.kind = EventKind.kPauseInterrupted;
	}
	var frames = _dartFramesFor(e);
	_pausedStack = Stack()
	..frames = frames
	..messages = [];
	if (frames.isNotEmpty) event.topFrame = frames.first;
	_streamNotify('Debug', event);
	}

	/// Handles resume events coming from the Chrome connection.
	Future<void> _resumeHandler(DebuggerResumedEvent e) async {
	// We can receive a resume event in the middle of a reload which will
	// result in a null isolate.
	var isolate = _appInspectorProvider()?.isolate;
	if (isolate == null) return;
	_pausedStack = null;
	_streamNotify(
	'Debug',
	Event()
	..kind = EventKind.kResume
	..isolate = toIsolateRef(isolate));
	}
	}

	/// Keeps track of the Dart and JS breakpoint Ids that correspond.
	class _Breakpoints {
	final Map<String, String> _byJsId = {};
	final Map<String, String> _byDartId = {};

	final AppInspectorProvider _appInspectorProvider;

	_Breakpoints(this._appInspectorProvider);

	/// Record the breakpoint.
	///
	/// Either [dartId] or the Dart breakpoint [bp] must be provided.
	void noteBreakpoint({String js, String dartId, Breakpoint bp}) {
	_byJsId[js] = dartId ?? bp?.id;
	_byDartId[dartId ?? bp?.id] = js;
	var isolate = _appInspectorProvider().isolate;
	if (bp != null) {
	isolate?.breakpoints?.add(bp);
	}
	}

	Breakpoint removeBreakpoint({String js, String dartId, Breakpoint bp}) {
	var isolate = _appInspectorProvider().isolate;
	_byJsId.remove(js);
	_byDartId.remove(dartId ?? bp?.id);
	Breakpoint dartBp;
	// TODO: Do something better than the default throw when it's not found.
	dartBp = bp ??
	isolate.breakpoints
	.firstWhere((b) => b.id == dartId, orElse: () => null);
	isolate?.breakpoints?.remove(dartBp);
	return dartBp;
	}

	String dartId(String jsId) => _byJsId[jsId];

	String jsId(String dartId) => _byDartId[dartId];
	}