DefaultUndoContext.java

package jetbrains.mps.smodel.undo;

/*Generated by MPS */

import org.jetbrains.mps.openapi.model.SNode;
import java.util.List;
import jetbrains.mps.smodel.SNodeUndoableAction;
import jetbrains.mps.internal.collections.runtime.ListSequence;
import jetbrains.mps.internal.collections.runtime.IWhereFilter;
import jetbrains.mps.internal.collections.runtime.ISelector;
import jetbrains.mps.lang.smodel.generator.smodelAdapter.SNodeOperations;

public class DefaultUndoContext implements UndoContext {
  @Override
  public Iterable<SNode> getVirtualFileNodes(List<SNodeUndoableAction> actions) {
    // There is a chance that so-called SNodeUndoableAction#isGlobal() actions may 
    // return null from SNodeUndoableAction#getRoot() method (e.g. if the root was deleted). 
    // In this case such actions does not have any influence on VirtualFiles collection associated 
    // with the currently executed command within Undo subsystem. 
    //   
    // Such actions (delete node) are always global and can be undone either from the project pane 
    // (in global context) or together with other actions executed in same command and associated 
    // with different VirtualFiles (as a part of undo called on another editor). 
    //   
    // We do not use SNodeUndoableAction#isGlobal() as a condition here because other "global" 
    // actions (add root) should probably be undoable within the current editor context (in case of 
    // multi-tabbed editors / adding new aspect node and immediately undoing that command). 
    return ListSequence.fromList(actions).where(new IWhereFilter<SNodeUndoableAction>() {
      public boolean accept(SNodeUndoableAction it) {
        return it.hasVirtualFile();
      }
    }).select(new ISelector<SNodeUndoableAction, SNode>() {
      public SNode select(SNodeUndoableAction it) {
        return SNodeOperations.getContainingRoot(((SNode) it.getAffectedNode()));
      }
    }).where(new IWhereFilter<SNode>() {
      public boolean accept(SNode it) {
        return (it != null);
      }
    });
  }
}