source: other-projects/rsyntax-textarea/src/java/org/fife/ui/rsyntaxtextarea/TokenMakerFactory.java@ 25584

/*
 * 12/12/2008
 *
 * TokenMakerFactory.java - A factory for TokenMakers.
 * 
 * This library is distributed under a modified BSD license.  See the included
 * RSyntaxTextArea.License.txt file for details.
 */
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;
    }


}