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Rich Internet Application Framework for GWT
There is a newer version: 2.3.1-gwt22
/*
 * Sencha GXT 2.3.1a - Sencha for GWT
 * Copyright(c) 2007-2013, Sencha, Inc.
 * [email protected]
 * 
 * http://www.sencha.com/products/gxt/license/
 */
 package com.extjs.gxt.ui.client.event;

import java.util.ArrayList;
import java.util.List;

import com.extjs.gxt.ui.client.data.ModelData;

/**
 * Provides a selection service where SelectionProviders can
 * register, allowing any listeners to be notified of selection events.
 */
public class SelectionService {

  private static SelectionService instance = new SelectionService();

  /**
   * Returns the singleton instance.
   * 
   * @return the service
   */
  public static SelectionService get() {
    return instance;
  }

  private SelectionChangedListener listener;
  private List> providers;
  private List> listeners;

  private SelectionService() {
    listener = new SelectionChangedListener() {
      public void selectionChanged(SelectionChangedEvent event) {
        onSelectionChanged(event);
      }
    };
    listeners = new ArrayList>();
    providers = new ArrayList>();
  }

  /**
   * Adds a listener to be notified of selection events from any registered
   * selection providers.
   * 
   * @param listener the listener to add
   */
  @SuppressWarnings({"unchecked", "rawtypes"})
  public void addListener(SelectionChangedListener listener) {
    listeners.add((SelectionChangedListener)listener);
  }

  /**
   * Returns a list of all current listeners.
   * 
   * @return the listeners
   */
  public List> getListeners() {
    return new ArrayList>(listeners);
  }

  /**
   * Returns the list of current providers.
   * 
   * @return the providers
   */
  public List> getProviders() {
    return new ArrayList>(providers);
  }

  /**
   * Registers a selection provider.
   * 
   * @param provider the provider to add
   */
  @SuppressWarnings({"unchecked", "rawtypes"})
  public void register(SelectionProvider provider) {
    provider.addSelectionChangedListener((SelectionChangedListener)listener);
    providers.add((SelectionProvider)provider);
  }

  /**
   * Removes a previously added listener.
   * 
   * @param listener the listener to remove
   */
  public void removeListener(SelectionChangedListener listener) {
    listeners.remove(listener);
  }

  /**
   * Unregisters a selection provider.
   * 
   * @param provider the provider to unregister
   */
  public void unregister(SelectionProvider provider) {
    provider.removeSelectionListener(listener);
    providers.remove(provider);
  }

  /**
   * Called when any selection changed event is received from any registered
   * providers.
   * 
   * @param event the selection changed event
   */
  protected void onSelectionChanged(SelectionChangedEvent event) {
    for (SelectionChangedListener l : listeners) {
      l.selectionChanged(event);
    }
  }
}