DocumentUndoProvider.java

/*
 * Copyright 2000-2015 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.intellij.openapi.command.impl;

import com.intellij.openapi.Disposable;
import com.intellij.openapi.command.undo.DocumentReference;
import com.intellij.openapi.command.undo.DocumentReferenceManager;
import com.intellij.openapi.command.undo.UndoConstants;
import com.intellij.openapi.command.undo.UndoManager;
import com.intellij.openapi.editor.Document;
import com.intellij.openapi.editor.EditorFactory;
import com.intellij.openapi.editor.event.DocumentEvent;
import com.intellij.openapi.editor.event.DocumentListener;
import com.intellij.openapi.fileEditor.FileDocumentManager;
import com.intellij.openapi.project.Project;
import com.intellij.openapi.util.Key;
import com.intellij.openapi.vfs.VirtualFile;
import org.jetbrains.annotations.Nullable;

public class DocumentUndoProvider implements Disposable {
  private static final Key<Boolean> UNDOING_EDITOR_CHANGE = Key.create("DocumentUndoProvider.UNDOING_EDITOR_CHANGE");

  private final Project myProject;

  DocumentUndoProvider(Project project) {
    MyEditorDocumentListener documentListener = new MyEditorDocumentListener();
    myProject = project;

    EditorFactory.getInstance().getEventMulticaster().addDocumentListener(documentListener, this);
  }

  @Override
  public void dispose() {
  }

  private UndoManagerImpl getUndoManager() {
    return (UndoManagerImpl)(myProject == null ? UndoManager.getGlobalInstance() : UndoManager.getInstance(myProject));
  }

  public static void startDocumentUndo(@Nullable Document doc) {
    if (doc != null) doc.putUserData(UNDOING_EDITOR_CHANGE, Boolean.TRUE);
  }

  public static void finishDocumentUndo(@Nullable Document doc) {
    if (doc != null) doc.putUserData(UNDOING_EDITOR_CHANGE, null);
  }

  private class MyEditorDocumentListener implements DocumentListener {
    @Override
    public void beforeDocumentChange(DocumentEvent e) {
      Document document = e.getDocument();
      if (!shouldProcess(document)) return;

      UndoManagerImpl undoManager = getUndoManager();
      if (undoManager.isActive() && isUndoable(document) && (undoManager.isUndoInProgress() || undoManager.isRedoInProgress()) && 
          document.getUserData(UNDOING_EDITOR_CHANGE) != Boolean.TRUE) {
        throw new IllegalStateException("Do not change documents during undo as it will break undo sequence.");
      }
    }

    @Override
    public void documentChanged(final DocumentEvent e) {
      Document document = e.getDocument();
      if (!shouldProcess(document)) return;

      UndoManagerImpl undoManager = getUndoManager();
      if (undoManager.isActive() && isUndoable(document)) {
        registerUndoableAction(e);
      }
      else {
        registerNonUndoableAction(document);
      }
    }
    
    private boolean shouldProcess(Document document) {
      if (myProject != null && myProject.isDisposed()) return false;
      return !UndoManagerImpl.isCopy(document) // if we don't ignore copy's events, we will receive notification
             // for the same event twice (from original document too)
             // and undo will work incorrectly
             && shouldRecordActions(document);
    }

    private boolean shouldRecordActions(final Document document) {
      if (document.getUserData(UndoConstants.DONT_RECORD_UNDO) == Boolean.TRUE) return false;

      final VirtualFile vFile = FileDocumentManager.getInstance().getFile(document);
      return vFile == null || vFile.getUserData(UndoConstants.DONT_RECORD_UNDO) != Boolean.TRUE;
    }

    private void registerUndoableAction(DocumentEvent e) {
      getUndoManager().undoableActionPerformed(new EditorChangeAction(e));
    }

    private void registerNonUndoableAction(final Document document) {
      DocumentReference ref = DocumentReferenceManager.getInstance().create(document);
      getUndoManager().nonundoableActionPerformed(ref, false);
    }

    private boolean isUndoable(Document document) {
      DocumentReference ref = DocumentReferenceManager.getInstance().create(document);
      VirtualFile file = ref.getFile();

      // Allow undo even from refresh if requested
      if (file != null && file.getUserData(UndoConstants.FORCE_RECORD_UNDO) == Boolean.TRUE) {
        return true;
      }
      return !UndoManagerImpl.isRefresh() || getUndoManager().isUndoOrRedoAvailable(ref);
    }
  }
}