ActionSeries.java :  » GWT » kiyaa » com » habitsoft » kiyaa » metamodel » Java Open Source

package com.habitsoft.kiyaa.metamodel;

import java.util.ArrayList;
import java.util.Collection;

import com.google.gwt.user.client.rpc.AsyncCallback;
import com.habitsoft.kiyaa.util.AsyncCallbackDirectProxy;

/**
 * This Action subclass runs a series of other actions.  If any of them fails,
 * it returns failure without running the ones that follow.
 */
public class ActionSeries extends Action {

  public ArrayList<Action> actions = new ArrayList<Action>();
  
  public ActionSeries() {
  }

  public ActionSeries(Action... actions) {
      for(Action a : actions) {
          this.actions.add(a);
      }
  }
  
  public void add(Action action) {
    if(action == null) throw new NullPointerException("Don't add null actions to an ActionSeries!");
    actions.add(action);
  }
  
  /**
   * Class to run each action in order.  If any action fails, returns
   * failure to the original callback.
   * 
   * Note that if actions are added to the list while this is running,
   * it WILL pick them up and also run them.
   */
  class Executor extends AsyncCallbackDirectProxy<Void> {
    int pos=0;
    
    public Executor(AsyncCallback<Void> delegate) {
      super(delegate);
    }

    @Override
    public void onSuccess(Void result) {
      performNext();
    }
    
    public void performNext() {
      if(pos < actions.size()) {
        Action nextAction = actions.get(pos);
        pos++;
        nextAction.performDeferred(this);
      } else {
        returnSuccess(null);
      }
    }
    
  }
  @Override
  public void perform(AsyncCallback<Void> callback) {
    if(actions.size() == 0) {
      callback.onSuccess(null);
      return;
    }
    new Executor(callback).performNext();
  }

  public boolean addAll(Collection<? extends Action> c) {
    return actions.addAll(c);
  }

  public void clear() {
    actions.clear();
  }

  public boolean contains(Object o) {
    return actions.contains(o);
  }

  public Action get(int index) {
    return actions.get(index);
  }

  public boolean isEmpty() {
    return actions.isEmpty();
  }

  public int size() {
    return actions.size();
  }
  

}