Detect concurrent edits.

dart/site/try/src/interaction_manager.dart

 // Copyright (c) 2014, 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.
 
 library trydart.interaction_manager;
 
 import 'dart:html';
 
 import 'dart:convert' show
     JSON;
@@ skipping 16 matching lines @@
 
 import 'compilation.dart' show
     currentSource,
     scheduleCompilation;
 
 import 'ui.dart' show
     currentTheme,
     hackDiv,
     mainEditorPane,
     observer,
-    outputDiv;
+    outputDiv,
+    statusDiv;
 
 import 'decoration.dart' show
     CodeCompletionDecoration,
     Decoration,
     DiagnosticDecoration,
     error,
     info,
     warning;
 
 import 'html_to_text.dart' show
@@ skipping 41 matching lines @@
 
   void onSelectionChange(Event event);
 
   /// Called when the content of a CompilationUnit changed.
   void onCompilationUnitChanged(CompilationUnit unit);
 
   Future<List<String>> projectFileNames();
 
   /// Called when the user selected a new project file.
   void onProjectFileSelected(String projectFile);
+
+  /// Called when notified about a project file changed (on the server).
+  void onProjectFileFsEvent(MessageEvent e);
 }
 
 /**
  * State machine for UI interactions.
  */
 class InteractionContext extends InteractionManager {
   InteractionState state;
 
   final Map<String, CompilationUnit> projectFiles = <String, CompilationUnit>{};
 
   CompilationUnit currentCompilationUnit =
       // TODO(ahe): Don't use a fake unit.
       new CompilationUnit('fake', '');
 
+  CompilationUnit lastSaved;
+
   InteractionContext()
       : super.internal() {
     state = new InitialState(this);
   }
 
   void onInput(Event event) => state.onInput(event);
 
   void onKeyUp(KeyboardEvent event) => state.onKeyUp(event);
 
   void onMutation(List<MutationRecord> mutations, MutationObserver observer) {
     return state.onMutation(mutations, observer);
   }
 
   void onSelectionChange(Event event) => state.onSelectionChange(event);
 
   void onCompilationUnitChanged(CompilationUnit unit) {
     return state.onCompilationUnitChanged(unit);
   }
 
   Future<List<String>> projectFileNames() => state.projectFileNames();
 
   void onProjectFileSelected(String projectFile) {
     return state.onProjectFileSelected(projectFile);
   }
+
+  void onProjectFileFsEvent(MessageEvent e) {
+    return state.onProjectFileFsEvent(e);
+  }
 }
 
 abstract class InteractionState implements InteractionManager {
   InteractionContext get context;
 
   void set state(InteractionState newState);
 
   void onStateChanged(InteractionState previous) {
     print('State change ${previous.runtimeType} -> ${runtimeType}.');
   }
@@ skipping 155 matching lines @@
       if (context.projectFiles.containsKey(unit.name)) {
         postProjectFileUpdate(unit);
       }
       scheduleCompilation();
     } else {
       print("Unexpected change to compilation unit '${unit.name}'.");
     }
   }
 
   void postProjectFileUpdate(CompilationUnit unit) {
+    context.lastSaved = unit;
     onError(ProgressEvent event) {
       HttpRequest request = event.target;
-      window.alert("Couldn't save '${unit.name}': ${request.responseText}");
+      statusDiv.text = "Couldn't save '${unit.name}': ${request.responseText}";
+      context.lastSaved = null;
     }
     new HttpRequest()
         ..open("POST", "/project/${unit.name}")
         ..onError.listen(onError)
         ..send(unit.content);
   }
 
   Future<List<String>> projectFileNames() {
     return getString('project?list').then((String response) {
       WebSocket socket = new WebSocket('ws://127.0.0.1:9090/ws/watch');
-      socket.onMessage.listen((MessageEvent e) {
-        print(e.data);
-      });
+      socket.onMessage.listen(context.onProjectFileFsEvent);
       return new List<String>.from(JSON.decode(response));
     });
   }
 
   void onProjectFileSelected(String projectFile) {
     // Disable editing whilst fetching data.
     mainEditorPane.contentEditable = 'false';
 
     CompilationUnit unit = context.projectFiles[projectFile];
     Future<CompilationUnit> future;
@@ skipping 26 matching lines @@
 
       transitionToInitialState();
       context.currentCompilationUnit = unit;
 
       // Install the code, which will trigger a call to onMutation.
       mainEditorPane.appendText(unit.content);
     });
   }
 
   void transitionToInitialState() {}
+
+  void onProjectFileFsEvent(MessageEvent e) {
+    Map map = JSON.decode(e.data);
+    List modified = map['modify'];
+    if (modified == null) return;
+    for (String name in modified) {
+      if (context.lastSaved != null && context.lastSaved.name == name) {
+        context.lastSaved = null;
+        continue;
+      }
+      if (context.currentCompilationUnit.name == name) {
+        mainEditorPane.contentEditable = false;
+        statusDiv.text = 'Modified on disk';
+      }
+    }
+  }
 }
 
 Future<String> getString(uri) {
   return new Future<String>.sync(() => HttpRequest.getString('$uri'));
 }
 
 class PendingInputState extends InitialState {
   PendingInputState(InteractionContext context)
       : super(context);
 
@@ skipping 294 matching lines @@
       event.getModifierState("Fn") ||
       event.getModifierState("Meta") ||
       event.getModifierState("NumLock") ||
       event.getModifierState("ScrollLock") ||
       event.getModifierState("Scroll") ||
       event.getModifierState("Win") ||
       event.getModifierState("Shift") ||
       event.getModifierState("SymbolLock") ||
       event.getModifierState("OS");
 }