DefaultTokenFactory.java

/*
 * 10/28/2004
 *
 * DefaultTokenFactory.java - Default token factory.
 * Copyright (C) 2004 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 javax.swing.text.Segment;

/**
 * This class generates tokens for a {@link TokenMaker}. This class is here because it reuses tokens when they aren't
 * needed anymore to prevent This class doesn't actually create new tokens every time <code>createToken</code> is
 * called. Instead, it internally keeps a stack of available already-created tokens. When more tokens are needed to
 * properly display a line, more tokens are added to the available stack. This saves from needless repetitive memory
 * allocation. However, it makes it IMPERATIVE that users call <code>resetTokenList</code> when creating a new token
 * list so that the token maker can keep an accurate list of available tokens.
 * <p>
 * 
 * NOTE: This class should only be used by {@link TokenMaker}; nobody else needs it!
 * 
 * @author Robert Futrell
 * @version 0.1
 */
class DefaultTokenFactory implements TokenFactory {

    private int size;
    private int increment;
    private Token[] tokenList;
    private int currentFreeToken;

    protected static final int DEFAULT_START_SIZE = 30;
    protected static final int DEFAULT_INCREMENT = 10;

    /**
     * Cosnstructor.
     */
    public DefaultTokenFactory() {
        this(DEFAULT_START_SIZE, DEFAULT_INCREMENT);
    }

    /**
     * Constructor.
     * 
     * @param size
     *            The initial number of tokens in this factory.
     * @param increment
     *            How many tokens to increment by when the stack gets empty.
     */
    public DefaultTokenFactory(int size, int increment) {

        this.size = size;
        this.increment = increment;
        this.currentFreeToken = 0;

        // Give us some tokens to initially work with.
        tokenList = new Token[size];
        for (int i = 0; i < size; i++)
            tokenList[i] = createInternalUseOnlyToken();

    }

    /**
     * Adds tokens to the internal token list. This is called whenever a request is made and no more tokens are
     * available.
     */
    private final void augmentTokenList() {
        Token[] temp = new Token[size + increment];
        System.arraycopy(tokenList, 0, temp, 0, size);
        size += increment;
        tokenList = temp;
        for (int i = 0; i < increment; i++) {
            tokenList[size - i - 1] = createInternalUseOnlyToken();
        }
        // System.err.println("... size up to: " + size);
    }

    /**
     * Creates a token for use internally by this token factory. This method should NOT be called externally; only by
     * this class and possibly subclasses.
     * 
     * @return A token to add to this token factory's internal stack. If a subclass wants to produce a stack of a token
     *         other than {@link DefaultToken}, then this method can be overridden to return a new instance of the
     *         desired token type.
     */
    protected Token createInternalUseOnlyToken() {
        return new DefaultToken();
    }

    /**
     * Returns a null token.
     * 
     * @return A null token.
     */
    public Token createToken() {
        Token token = tokenList[currentFreeToken];
        token.text = null;
        token.type = Token.NULL;
        token.offset = -1;
        token.setNextToken(null);
        currentFreeToken++;
        if (currentFreeToken == size)
            augmentTokenList();
        return token;
    }

    /**
     * Returns a token.
     * 
     * @param line
     *            The segment from which to get the token's text.
     * @param beg
     *            The starting offset of the token's text in the segment.
     * @param end
     *            The ending offset of the token's text in the segment.
     * @param startOffset
     *            The offset in the document of the token.
     * @param type
     *            The type of token.
     * @return The token.
     */
    public Token createToken(final Segment line, final int beg,
            final int end, final int startOffset, final int type) {
        return createToken(line.array, beg, end, startOffset, type);
    }

    /**
     * Returns a token.
     * 
     * @param line
     *            The segment from which to get the token's text.
     * @param beg
     *            The starting offset of the token's text in the segment.
     * @param end
     *            The ending offset of the token's text in the segment.
     * @param startOffset
     *            The offset in the document of the token.
     * @param type
     *            The type of token.
     * @return The token.
     */
    public Token createToken(final char[] line, final int beg,
            final int end, final int startOffset, final int type) {
        Token token = tokenList[currentFreeToken];
        token.set(line, beg, end, startOffset, type);
        currentFreeToken++;
        if (currentFreeToken == size)
            augmentTokenList();
        return token;
    }

    /**
     * Resets the state of this token maker. This method should be called by the <code>TokenMaker</code> every time a
     * token list is generated for a new line so the tokens can be reused.
     */
    public void resetAllTokens() {
        currentFreeToken = 0;
    }

}