featuredescriptions.java

Mandarax是一个规则引擎的纯Java实现。它支持多类型的事实和基于反映的规则

/*
 * Copyright (C) 1999-2004 <A href="http://www-ist.massey.ac.nz/JBDietrich" target="_top">Jens Dietrich</a>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package org.mandarax.kernel;


import java.util.Collection;
import java.util.Properties;
import java.util.TreeSet;

/**
 * Abstract class providing a description of features of an object.
 * Used to describe features of knowledge bases and inference engines.
 * The most easiest way to use this class is to define an anonymous
 * subclass, to override the constructor and to add a list of <code>support()</code>
 * statements in the <code>initialize()</code> for the supported features.
 * @author <A href="http://www-ist.massey.ac.nz/JBDietrich" target="_top">Jens Dietrich</A>
 * @version 3.4 <7 March 05>
 * @since 1.0
 */
public abstract class FeatureDescriptions {
    protected Collection    supported    = new TreeSet ();
    protected Properties descriptions = new Properties();
    /**
     * Constructor.
     */
    public FeatureDescriptions() {
        super ();
        initialize ();
    }
    /**
     * Get a description string of the respective feature.
     * @return the description
     * @param featureName the name of the feature
     */
    public String getFeatureDescription(String featureName) {
        return descriptions.getProperty (featureName);
    }
    /**
     * Get a collection of all supported features.
     * @return a collection of supported features
     */
    public Collection getSupportedFeatures() {
        return supported;
    }
    /**
     * Initialize the object. Override this method and invoke this
     * implementation using <code>super.initialize()</code> first.
     */
    protected void initialize() {
        // nothing to do here   
    }
    /**
     * Indicates whether the named feature is supported.
     * @return true if the respective featurte is supported, false otherwise
     * @param aFeatureName the name of the feature
     */
    public boolean isFeatureSupported(String aFeatureName) {
        return supported.contains (aFeatureName);
    }
    /**
     * Register a feature to be supported.
     * @param featureName the name of the feature
     */
    protected void support(String featureName) {
        supported.add (featureName);
    }
}