keep markers until explicitly invalidated to keep syncing after last char is deleted

xml/impl/src/com/intellij/codeInsight/editorActions/XmlTagNameSynchronizer.java

@@ -62,12 +62,21 @@ public class XmlTagNameSynchronizer extends CommandAdapter implements Applicatio
 
       @Override
       public void editorReleased(@NotNull EditorFactoryEvent event) {
-        event.getEditor().getDocument().putUserData(SYNCHRONIZER_KEY, null);
+        uninstallSynchronizer(event);
       }
     }, ApplicationManager.getApplication());
     processor.addCommandListener(this);
   }
 
+  public void uninstallSynchronizer(@NotNull EditorFactoryEvent event) {
+    final Document document = event.getEditor().getDocument();
+    final TagNameSynchronizer synchronizer = findSynchronizer(document);
+    if (synchronizer != null) {
+      synchronizer.clearMarkers();
+    }
+    document.putUserData(SYNCHRONIZER_KEY, null);
+  }
+
   private void installSynchronizer(Editor editor) {
     final Project project = editor.getProject();
     if (project == null) return;
@@ -98,24 +107,15 @@ public class XmlTagNameSynchronizer extends CommandAdapter implements Applicatio
 
   }
 
-  @Override
-  public void commandStarted(CommandEvent event) {
-    final TagNameSynchronizer synchronizer = findSynchronizer(event);
-    if (synchronizer != null) {
-      synchronizer.commandStarted();
-    }
-  }
-
   @Nullable
-  public TagNameSynchronizer findSynchronizer(CommandEvent event) {
-    if (!WebEditorOptions.getInstance().isSyncTagEditing()) return null;
-    final Document document = event.getDocument();
-    return document != null ? document.getUserData(SYNCHRONIZER_KEY) : null;
+  public TagNameSynchronizer findSynchronizer(final Document document) {
+    if (!WebEditorOptions.getInstance().isSyncTagEditing() || document == null) return null;
+    return document.getUserData(SYNCHRONIZER_KEY);
   }
 
   @Override
   public void beforeCommandFinished(CommandEvent event) {
-    final TagNameSynchronizer synchronizer = findSynchronizer(event);
+    final TagNameSynchronizer synchronizer = findSynchronizer(event.getDocument());
     if (synchronizer != null) {
       synchronizer.beforeCommandFinished();
     }
@@ -127,7 +127,7 @@ public class XmlTagNameSynchronizer extends CommandAdapter implements Applicatio
     private enum State {INITIAL, TRACKING, APPLYING}
 
     private final Editor myEditor;
-    private State myState;
+    private State myState = State.INITIAL;
     private final List<Couple<RangeMarker>> myMarkers = new SmartList<Couple<RangeMarker>>();
 
     public TagNameSynchronizer(Editor editor, Project project) {
@@ -216,6 +216,7 @@ public class XmlTagNameSynchronizer extends CommandAdapter implements Applicatio
         leaderAndSupport.second.dispose();
       }
       myMarkers.clear();
+      myState = State.INITIAL;
     }
 
     private RangeMarker createTagNameMarker(Caret caret) {
@@ -248,11 +249,6 @@ public class XmlTagNameSynchronizer extends CommandAdapter implements Applicatio
       return Character.isJavaIdentifierPart(c) || c == ':';
     }
 
-    public void commandStarted() {
-      myState = State.INITIAL;
-      clearMarkers();
-    }
-
     public void beforeCommandFinished() {
       if (myMarkers.isEmpty()) return;
 
@@ -270,7 +266,8 @@ public class XmlTagNameSynchronizer extends CommandAdapter implements Applicatio
           }
         }
       });
-      clearMarkers();
+
+      myState = State.TRACKING;
     }
 
     private static RangeMarker findSupport(RangeMarker leader, PsiFile file, Document document) {

xml/tests/src/com/intellij/codeInsight/completion/XmlSyncTagTest.java

@@ -38,6 +38,10 @@ public class XmlSyncTagTest extends LightPlatformCodeInsightFixtureTestCase {
     doTest("<div<caret>></div>", "\b\b\b", "<></>");
   }
 
+  public void testLastCharDeletedAndNewAdded() {
+    doTest("<a<caret> alt='</>'></a>", "\bb", "<b alt='</>'></b>");
+  }
+
   public void testSelection() {
     doTest("<<selection>div</selection>></div>", "b", "<b></b>");
   }
@@ -80,17 +84,20 @@ public class XmlSyncTagTest extends LightPlatformCodeInsightFixtureTestCase {
 
   private void doTest(final String text, final String toType, final String result) {
     myFixture.configureByText(XmlFileType.INSTANCE, text);
-    CommandProcessor.getInstance().executeCommand(getProject(), new Runnable() {
-      @Override
-      public void run() {
-        ApplicationManager.getApplication().runWriteAction(new Runnable() {
-          @Override
-          public void run() {
-            myFixture.type(toType);
-          }
-        });
-      }
-    }, "Typing", DocCommandGroupId.noneGroupId(myFixture.getEditor().getDocument()), myFixture.getEditor().getDocument());
+    for (int i = 0; i < toType.length(); i++) {
+      final char c = toType.charAt(i);
+      CommandProcessor.getInstance().executeCommand(getProject(), new Runnable() {
+        @Override
+        public void run() {
+          ApplicationManager.getApplication().runWriteAction(new Runnable() {
+            @Override
+            public void run() {
+              myFixture.type(c);
+            }
+          });
+        }
+      }, "Typing", DocCommandGroupId.noneGroupId(myFixture.getEditor().getDocument()), myFixture.getEditor().getDocument());
+    }
     myFixture.checkResult(result);
   }