MenuParser.java

import je3.reflect.*;
import java.awt.event.*;
import java.util.MissingResourceException;
import javax.swing.*;
import java.util.StringTokenizer;

/**
 * This class parses a JMenu or JPopupMenu from textual descriptions found in
 * a GUIResourceBundle.  The grammar is straightforward: the menu label
 * followed by a colon and a list of menu items.  Menu items that begin with
 * a '>' character are submenus.  Menu items that begin with a '-' character
 * are separators.  All other items are action names.
 **/
public class MenuParser extends ResourceParser {
    static final Class[  ] supportedTypes = new Class[  ] {
        JMenu.class, JPopupMenu.class  // This class handles two resource types
    };

    public Class[  ] getResourceTypes( ) { return supportedTypes; }

    public Object parse(GUIResourceBundle bundle, String key, Class type) //throws MissingResourceException, MalformedResourceException
        //throws MissingResourceException, MalformedResourceException
    {
        // Get the string value of the key
        String menudef = bundle.getString(key);

        // Break it up into words, ignoring whitespace, colons, and commas
        StringTokenizer st = new StringTokenizer(menudef, " \t:,");

        // The first word is the label of the menu
        String menuLabel = st.nextToken( );

        // Create either a JMenu or JPopupMenu
        JMenu menu = null;
        JPopupMenu popup = null;
        if (type == JMenu.class) menu = new JMenu(menuLabel);
        else popup = new JPopupMenu(menuLabel);

        // Then loop through the rest of the words, creating a JMenuItem
        // for each one.  Accumulate these items in a list
        while(st.hasMoreTokens( )) {
            String item = st.nextToken( );     // the next word
            char firstchar = item.charAt(0);  // determines type of menu item
            switch(firstchar) {
            case '-':   // words beginning with - add a separator to the menu
                if (menu != null) menu.addSeparator( );
                else popup.addSeparator( );
                break;
            case '>':   // words beginning with > are submenu names
                // strip off the > character, and recurse to parse the submenu
                item = item.substring(1);  
                // Parse a submenu and add it to the list of items
                JMenu submenu = (JMenu)parse(bundle, item, JMenu.class);
                if (menu != null) menu.add(submenu);
                else popup.add(submenu);
                break;
            case '!': // words beginning with ! are action names
                item = item.substring(1);   // strip off the ! character
                /* falls through */         // fall through to the next case
            default:  // By default all other words are taken as action names
                // Look up the named action and add it to the menu
                Action action = (Action)bundle.getResource(item, Action.class);
                if (menu != null) menu.add(action);
                else popup.add(action);
                break;
            }
        }

        // Finally, return the menu or the popup menu
        if (menu != null) return menu;
        else return popup;
    }
}