LoadStrategy (#894)

Towards #893

Collect module strategy and related loading logic into new `LoadStrategy` abstraction. This will allow us to  make an explicit contract for the `RequireStrategy`.

Author: grouma

dwds/CHANGELOG.md

@@ -1,3 +1,12 @@
+## 2.0.0-dev
+
+**Breaking Changes:**
+- Now require a `LoadStrategy` to `Dwds.start`. This package defines two
+  compatible load strategies, `RequireStrategy` and `LegacyStrategy.
+- `Dwds.start` function signature has been changed to accept one more parameter
+  of new interface type `ExpressionCompiler` to support expression
+  evaluation
+
 ## 1.0.1
 
 - Make the `root` optional for the `ProxyServerAssetReader`.
@@ -21,9 +30,6 @@
   clearly defined. The new abstraction is now consumed through `dwds.dart`.
 - `BuildRunnerAssetHandler` has been renamed to `ProxyServerAssetReader` and is
   now consumed through `dwds.dart`.
-- `Dwds.start` function signature has been changed to accept one more parameter
-  of new interface type `ExpressionCompiler` to support expression
-  evaluation
 
 ## 0.9.0
 

dwds/lib/dwds.dart

@@ -4,25 +4,29 @@
 
 import 'dart:async';
 
-import 'package:dwds/data/build_result.dart';
-import 'package:dwds/src/services/expression_compiler.dart';
-import 'package:dwds/src/utilities/shared.dart';
 import 'package:logging/logging.dart';
 import 'package:meta/meta.dart';
 import 'package:shelf/shelf.dart';
 import 'package:webkit_inspection_protocol/webkit_inspection_protocol.dart';
 
+import 'data/build_result.dart';
 import 'src/connections/app_connection.dart';
 import 'src/connections/debug_connection.dart';
 import 'src/handlers/dev_handler.dart';
 import 'src/handlers/injected_handler.dart';
+import 'src/loaders/strategy.dart';
 import 'src/readers/asset_reader.dart';
 import 'src/servers/devtools.dart';
 import 'src/servers/extension_backend.dart';
+import 'src/services/expression_compiler.dart';
+import 'src/utilities/shared.dart';
 
 export 'src/connections/app_connection.dart' show AppConnection;
 export 'src/connections/debug_connection.dart' show DebugConnection;
 export 'src/handlers/dev_handler.dart' show AppConnectionException;
+export 'src/loaders/legacy.dart' show LegacyStrategy;
+export 'src/loaders/require.dart' show RequireStrategy;
+export 'src/loaders/strategy.dart' show LoadStrategy, ReloadConfiguration;
 export 'src/readers/asset_reader.dart' show AssetReader;
 export 'src/readers/frontend_server_asset_reader.dart'
     show FrontendServerAssetReader;
@@ -33,8 +37,6 @@ export 'src/services/expression_compiler.dart'
 
 typedef ConnectionProvider = Future<ChromeConnection> Function();
 typedef UrlEncoder = Future<String> Function(String url);
-enum ReloadConfiguration { none, hotReload, hotRestart, liveReload }
-enum ModuleStrategy { requireJS, legacy }
 
 /// The Dart Web Debug Service.
 class Dwds {
@@ -68,33 +70,32 @@ class Dwds {
     return DebugConnection(appDebugServices);
   }
 
-  static Future<Dwds> start(
-      {@required AssetReader assetReader,
-      @required Stream<BuildResult> buildResults,
-      @required ConnectionProvider chromeConnection,
-      @required bool enableDebugging,
-      String hostname,
-      ReloadConfiguration reloadConfiguration,
-      bool useSseForDebugProxy,
-      bool serveDevTools,
-      LogWriter logWriter,
-      bool verbose,
-      bool enableDebugExtension,
-      ModuleStrategy moduleStrategy,
-      UrlEncoder urlEncoder,
-      @deprecated bool restoreBreakpoints,
-      // TODO(annagrin): make expressionCompiler argument required
-      // [issue 881](https://github.com/dart-lang/webdev/issues/881)
-      ExpressionCompiler expressionCompiler}) async {
+  static Future<Dwds> start({
+    @required AssetReader assetReader,
+    @required Stream<BuildResult> buildResults,
+    @required ConnectionProvider chromeConnection,
+    @required LoadStrategy loadStrategy,
+    @required bool enableDebugging,
+    bool enableDebugExtension,
+    String hostname,
+    bool useSseForDebugProxy,
+    bool serveDevTools,
+    LogWriter logWriter,
+    bool verbose,
+    UrlEncoder urlEncoder,
+    // TODO(annagrin): make expressionCompiler argument required
+    // [issue 881](https://github.com/dart-lang/webdev/issues/881)
+    ExpressionCompiler expressionCompiler,
+    @deprecated bool restoreBreakpoints,
+  }) async {
     hostname ??= 'localhost';
-    reloadConfiguration ??= ReloadConfiguration.none;
     enableDebugging ??= true;
     enableDebugExtension ??= false;
     useSseForDebugProxy ??= true;
     serveDevTools ??= true;
     logWriter ??= (level, message) => print(message);
     verbose ??= false;
-    globalModuleStrategy = moduleStrategy ?? ModuleStrategy.requireJS;
+    globalLoadStrategy = loadStrategy;
     restoreBreakpoints ??= false;
 
     DevTools devTools;
@@ -135,7 +136,6 @@ class Dwds {
 
     return Dwds._(
       createInjectedHandler(
-        reloadConfiguration,
         extensionUri: extensionUri,
         urlEncoder: urlEncoder,
       ),

dwds/lib/src/debugging/classes.dart

@@ -2,6 +2,7 @@
 // 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 '../loaders/strategy.dart';
 import '../utilities/domain.dart';
 import '../utilities/shared.dart';
 import '../utilities/wrapped_service.dart';
@@ -68,7 +69,7 @@ class ClassHelper extends Domain {
     var rawName = classRef.name.split('<').first;
     var expression = '''
     (function() {
-      ${getLibrarySnippet(libraryRef.uri)}
+      ${globalLoadStrategy.loadLibrarySnippet(libraryRef.uri)}
       var result = {};
       var clazz = library["$rawName"];
       var descriptor = {

dwds/lib/src/debugging/dart_scope.dart

@@ -2,8 +2,7 @@
 // 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 'package:dwds/src/utilities/shared.dart';
-
+import '../loaders/strategy.dart';
 import '../utilities/objects.dart';
 import 'debugger.dart';
 
@@ -59,7 +58,7 @@ Future<Property> _findMissingThis(String callFrameId, Debugger debugger) async {
   final findCurrent = '''
         (function (THIS) {
            if (THIS === window) { return null; }
-           $getLibraries
+           ${globalLoadStrategy.loadLibrariesSnippet}
            for (let lib of libs) {
              if (lib === THIS) {
                 return null;

dwds/lib/src/debugging/debugger.dart

@@ -10,6 +10,7 @@ import 'package:meta/meta.dart';
 import 'package:webkit_inspection_protocol/webkit_inspection_protocol.dart'
     hide StackTrace;
 
+import '../loaders/strategy.dart';
 import '../readers/asset_reader.dart';
 import '../services/chrome_proxy_service.dart';
 import '../utilities/conversions.dart';
@@ -388,7 +389,7 @@ class Debugger extends Domain {
     // want. To make those alternatives easier in JS, pass both count and end.
     var expression = '''
         function (offset, count, end) {
-          const sdk = $loadModule("dart_sdk");
+          const sdk = ${globalLoadStrategy.loadModuleSnippet}("dart_sdk");
           if (sdk.core.Map.is(this)) {
             const entries = sdk.dart.dload(this, "entries");
             const skipped = sdk.dart.dsend(entries, "skip", [offset])

dwds/lib/src/debugging/inspector.dart

@@ -13,6 +13,7 @@ import 'package:webkit_inspection_protocol/webkit_inspection_protocol.dart';
 import '../connections/app_connection.dart';
 import '../debugging/location.dart';
 import '../debugging/remote_debugger.dart';
+import '../loaders/strategy.dart';
 import '../readers/asset_reader.dart';
 import '../utilities/conversions.dart';
 import '../utilities/dart_uri.dart';
@@ -151,7 +152,7 @@ class AppInspector extends Domain {
   Future<RemoteObject> loadField(RemoteObject receiver, String fieldName) {
     var load = '''
         function() {
-          return $loadModule("dart_sdk").dart.dloadRepl(this, "$fieldName");
+          return ${globalLoadStrategy.loadModuleSnippet}("dart_sdk").dart.dloadRepl(this, "$fieldName");
         }
         ''';
     return jsCallFunctionOn(receiver, load, []);
@@ -170,7 +171,7 @@ class AppInspector extends Domain {
     var send = '''
         function () {
           if (!(this.__proto__)) { return 'Instance of PlainJavaScriptObject';}
-          return $loadModule("dart_sdk").dart.dsendRepl(this, "$methodName", arguments);
+          return ${globalLoadStrategy.loadModuleSnippet}("dart_sdk").dart.dsendRepl(this, "$methodName", arguments);
         }
         ''';
     var remote = await jsCallFunctionOn(receiver, send, positionalArgs);
@@ -251,7 +252,7 @@ class AppInspector extends Domain {
       String expression, String libraryUri) {
     var evalExpression = '''
 (function() {
-  ${getLibrarySnippet(libraryUri)};
+  ${globalLoadStrategy.loadLibrarySnippet(libraryUri)};
   return library.$expression;
 })();
 ''';
@@ -278,7 +279,7 @@ class AppInspector extends Domain {
       Library library, String jsFunction, List<RemoteObject> arguments) async {
     var findLibrary = '''
 (function() {
-  ${getLibrarySnippet(library.uri)};
+  ${globalLoadStrategy.loadLibrarySnippet(library.uri)};
   return library;
 })();
 ''';
@@ -294,7 +295,7 @@ class AppInspector extends Domain {
     var arguments = scope.values.map(remoteObjectFor).toList();
     var evalExpression = '''
 function($argsString) {
-  ${getLibrarySnippet(library.uri)};
+  ${globalLoadStrategy.loadLibrarySnippet(library.uri)};
   return library.$expression;
 }
     ''';
@@ -370,7 +371,7 @@ function($argsString) {
     (function() {
       var uris = JSON.parse('$listAsJson');
       var allScripts = {};
-      var sdkUtils = $loadModule('dart_sdk').dart;
+      var sdkUtils = ${globalLoadStrategy.loadModuleSnippet}('dart_sdk').dart;
       for (var uri of uris) {
         var parts = sdkUtils.getParts(uri);
         allScripts[uri] = parts;
@@ -414,7 +415,7 @@ function($argsString) {
   /// Runs an eval on the page to compute all existing registered extensions.
   Future<List<String>> _getExtensionRpcs() async {
     var expression =
-        "$loadModule('dart_sdk').developer._extensions.keys.toList();";
+        "${globalLoadStrategy.loadModuleSnippet}('dart_sdk').developer._extensions.keys.toList();";
     var extensionsResult =
         await remoteDebugger.sendCommand('Runtime.evaluate', params: {
       'expression': expression,

dwds/lib/src/debugging/instance.dart

@@ -6,6 +6,7 @@ import 'dart:math';
 
 import 'package:webkit_inspection_protocol/webkit_inspection_protocol.dart';
 
+import '../loaders/strategy.dart';
 import '../utilities/conversions.dart';
 import '../utilities/domain.dart';
 import '../utilities/objects.dart';
@@ -172,7 +173,7 @@ class InstanceHelper extends Domain {
     // values that we need to be RemoteObject, e.g. a List of int.
     var expression = '''
       function() {
-        var sdkUtils = $loadModule('dart_sdk').dart;
+        var sdkUtils = ${globalLoadStrategy.loadModuleSnippet}('dart_sdk').dart;
         var entries = sdkUtils.dloadRepl(this, "entries");
         entries = sdkUtils.dsendRepl(entries, "toList", []);
         function asKey(entry) {
@@ -268,7 +269,7 @@ class InstanceHelper extends Domain {
     // of these as special.
     // TODO(alanknight): Handle superclass fields.
     final fieldNameExpression = '''function() {
-      const sdk = $loadModule("dart_sdk");
+      const sdk = ${globalLoadStrategy.loadModuleSnippet}("dart_sdk");
       const sdk_utils = sdk.dart;
       const fields = sdk_utils.getFields(sdk_utils.getType(this)) || [];
       if (!fields && (dart_sdk._interceptors.JSArray.is(this) ||

dwds/lib/src/debugging/libraries.dart

@@ -4,6 +4,7 @@
 
 import 'package:dwds/src/debugging/inspector.dart';
 
+import '../loaders/strategy.dart';
 import '../utilities/domain.dart';
 import '../utilities/shared.dart';
 import '../utilities/wrapped_service.dart';
@@ -26,7 +27,7 @@ class LibraryHelper extends Domain {
     if (_libraryRefsById.isNotEmpty) return _libraryRefsById.values.toList();
     var expression = '''
       (function() {
-        $getLibraries
+        ${globalLoadStrategy.loadLibrariesSnippet}
         return libs;
       })()
      ''';
@@ -64,7 +65,7 @@ class LibraryHelper extends Domain {
     // Fetch information about all the classes in this library.
     var expression = '''
     (function() {
-      ${getLibrarySnippet(libraryRef.uri)}
+      ${globalLoadStrategy.loadLibrarySnippet(libraryRef.uri)}
       var result = {};
       var classes = Object.values(Object.getOwnPropertyDescriptors(library))
         .filter((p) => 'value' in p)

dwds/lib/src/debugging/metadata.dart

@@ -6,6 +6,7 @@ import 'package:webkit_inspection_protocol/webkit_inspection_protocol.dart';
 
 import '../debugging/classes.dart';
 import '../debugging/inspector.dart';
+import '../loaders/strategy.dart';
 import '../services/chrome_proxy_service.dart';
 import '../utilities/shared.dart';
 import '../utilities/wrapped_service.dart';
@@ -51,7 +52,7 @@ class ClassMetaData {
     try {
       var evalExpression = '''
       function(arg) {
-        const sdkUtils = $loadModule('dart_sdk').dart;
+        const sdkUtils = ${globalLoadStrategy.loadModuleSnippet}('dart_sdk').dart;
         const classObject = sdkUtils.getReifiedType(arg);
         const isFunction = sdkUtils.AbstractFunctionType.is(classObject);
         const result = {};
@@ -101,7 +102,7 @@ class FunctionMetaData {
       RemoteDebugger remoteDebugger, RemoteObject remoteObject) async {
     var evalExpression = '''
       function(remoteObject) {
-        var sdkUtils = $loadModule('dart_sdk').dart;
+        var sdkUtils = ${globalLoadStrategy.loadModuleSnippet}('dart_sdk').dart;
         var name = remoteObject.name;
         if(remoteObject._boundObject) {
          name = sdkUtils.getType(remoteObject._boundObject).name +

dwds/lib/src/debugging/modules.dart

@@ -7,6 +7,7 @@ import 'dart:async';
 import 'package:dwds/src/debugging/execution_context.dart';
 import 'package:path/path.dart' as p;
 
+import '../loaders/strategy.dart';
 import '../utilities/dart_uri.dart';
 import '../utilities/shared.dart';
 import 'remote_debugger.dart';
@@ -110,7 +111,7 @@ class Modules {
   Future<void> _initializeMapping() async {
     var expression = '''
     (function() {
-          var dart = $loadModule('dart_sdk').dart;
+          var dart = ${globalLoadStrategy.loadModuleSnippet}('dart_sdk').dart;
           var result = {};
           dart.getModuleNames().forEach(function(module){
             Object.keys(dart.getModuleLibraries(module)).forEach(

dwds/lib/src/handlers/injected_handler.dart

@@ -7,7 +7,7 @@ import 'dart:io';
 import 'dart:isolate';
 
 import 'package:crypto/crypto.dart';
-import 'package:dwds/src/utilities/shared.dart';
+import 'package:dwds/src/loaders/strategy.dart';
 import 'package:dwds/src/version.dart';
 import 'package:shelf/shelf.dart';
 
@@ -26,9 +26,7 @@ const mainExtensionMarker = '/* MAIN_EXTENSION_MARKER */';
 const _clientScript = 'dwds/src/injected/client';
 
 Handler Function(Handler) createInjectedHandler(
-        ReloadConfiguration configuration,
-        {String extensionUri,
-        UrlEncoder urlEncoder}) =>
+        {String extensionUri, UrlEncoder urlEncoder}) =>
     (innerHandler) {
       return (Request request) async {
         if (request.url.path.endsWith('$_clientScript.js')) {
@@ -74,7 +72,6 @@ Handler Function(Handler) createInjectedHandler(
               requestedUriBase = await urlEncoder(requestedUriBase);
             }
             body += _injectedClientJs(
-              configuration,
               appId,
               mainFunction,
               requestedUriBase,
@@ -99,7 +96,6 @@ Handler Function(Handler) createInjectedHandler(
     };
 
 String _injectedClientJs(
-  ReloadConfiguration configuration,
   String appId,
   String mainFunction,
   String requestedUriBase, {
@@ -108,11 +104,11 @@ String _injectedClientJs(
   var injectedBody = '// Injected by webdev for build results support.\n'
       'window.\$dartAppId = "$appId";\n'
       'window.\$dartRunMain = $mainFunction;\n'
-      'window.\$dartReloadConfiguration = "$configuration";\n'
+      'window.\$dartReloadConfiguration = "${globalLoadStrategy.reloadConfiguration}";\n'
       'window.\$dartLoader.forceLoadModule("$_clientScript");\n'
-      'window.\$dartModuleStrategy = "$loadModule";\n'
+      'window.\$dartModuleStrategy = "${globalLoadStrategy.id}";\n'
       'window.\$dartUriBase = "$requestedUriBase";\n'
-      'window.\$loadModuleConfig = $loadModule;\n'
+      'window.\$loadModuleConfig = ${globalLoadStrategy.loadModuleSnippet};\n'
       'window.\$dwdsVersion = "$packageVersion";\n';
   if (extensionUri != null) {
     injectedBody += 'window.\$dartExtensionUri = "$extensionUri";\n';