TokenMakerFactory.java

/*
 * 12/12/2008
 *
 * TokenMakerFactory.java - A factory for TokenMakers.
 * Copyright (C) 2008 Robert Futrell
 * robert_futrell at users.sourceforge.net
 * http://fifesoft.com/rsyntaxtextarea
 *
 * 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 2.1 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.fife.ui.rsyntaxtextarea;

import java.util.Map;
import java.util.Set;

import org.fife.ui.rsyntaxtextarea.modes.PlainTextTokenMaker;

/**
 * A factory that maps syntax styles to {@link TokenMaker}s capable of splitting text into tokens for those syntax
 * styles.
 * 
 * @author Robert Futrell
 * @version 1.0
 */
public abstract class TokenMakerFactory {

    /**
     * If this system property is set, a custom <code>TokenMakerFactory</code> of the specified class will be used as
     * the default token maker factory.
     */
    public static final String PROPERTY_DEFAULT_TOKEN_MAKER_FACTORY =
            "TokenMakerFactory";

    /**
     * The singleton default <code>TokenMakerFactory</code> instance.
     */
    private static TokenMakerFactory DEFAULT_INSTANCE;

    /**
     * Creates and returns a mapping from keys to the names of {@link TokenMaker} implementation classes. When
     * {@link #getTokenMaker(String)} is called with a key defined in this map, a <code>TokenMaker</code> of the
     * corresponding type is returned.
     * 
     * @return The map.
     */
    protected abstract Map createTokenMakerKeyToClassNameMap();

    /**
     * Returns the default <code>TokenMakerFactory</code> instance. This is the factory used by all
     * {@link RSyntaxDocument}s by default.
     * 
     * @return The factory.
     * @see #setDefaultInstance(TokenMakerFactory)
     */
    public static synchronized TokenMakerFactory getDefaultInstance() {
        if (DEFAULT_INSTANCE == null) {
            String clazz = null;
            try {
                clazz = System.getProperty(PROPERTY_DEFAULT_TOKEN_MAKER_FACTORY);
            } catch (java.security.AccessControlException ace) {
                clazz = null; // We're in an applet; take default.
            }
            if (clazz == null) {
                clazz = "org.fife.ui.rsyntaxtextarea.DefaultTokenMakerFactory";
            }
            try {
                DEFAULT_INSTANCE = (TokenMakerFactory) Class.forName(clazz).
                        newInstance();
            } catch (RuntimeException re) { // FindBugs
                throw re;
            } catch (Exception e) {
                e.printStackTrace();
                throw new InternalError("Cannot find TokenMakerFactory: " +
                        clazz);
            }
        }
        return DEFAULT_INSTANCE;
    }

    /**
     * Returns a {@link TokenMaker} for the specified key.
     * 
     * @param key
     *            The key.
     * @return The corresponding <code>TokenMaker</code>, or {@link PlainTextTokenMaker} if none matches the specified
     *         key.
     */
    public final TokenMaker getTokenMaker(String key) {
        TokenMaker tm = getTokenMakerImpl(key);
        if (tm == null) {
            tm = new PlainTextTokenMaker();
        }
        return tm;
    }

    /**
     * Returns a {@link TokenMaker} for the specified key.
     * 
     * @param key
     *            The key.
     * @return The corresponding <code>TokenMaker</code>, or <code>null</code> if none matches the specified key.
     */
    protected abstract TokenMaker getTokenMakerImpl(String key);

    /**
     * Returns the set of keys that this factory maps to token makers.
     * 
     * return The set of keys.
     */
    public abstract Set keySet();

    /**
     * Sets the default <code>TokenMakerFactory</code> instance. This is the factory used by all future
     * {@link RSyntaxDocument}s by default. <code>RSyntaxDocument</code>s that have already been created are not
     * affected.
     * 
     * @param tmf
     *            The factory.
     * @throws IllegalArgumentException
     *             If <code>tmf</code> is <code>null</code>.
     * @see #getDefaultInstance()
     */
    public static synchronized void setDefaultInstance(TokenMakerFactory tmf) {
        if (tmf == null) {
            throw new IllegalArgumentException("tmf cannot be null");
        }
        DEFAULT_INSTANCE = tmf;
    }

}