swing/text/WhitespaceBasedBreakIterator.java

/*
 * Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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 General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
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 */

package javax.swing.text;

import java.text.BreakIterator;
import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
import java.util.Arrays;

/**
 * A simple whitespace-based BreakIterator implementation.
 *
 * @author Sergey Groznyh
 */
class WhitespaceBasedBreakIterator extends BreakIterator {
    private char[] text = new char[0];
    private int[] breaks = new int[] { 0 } ;
    private int pos = 0;

    /**
     * Calculate break positions eagerly parallel to reading text.
     */
    public void setText(CharacterIterator ci) {
        int begin = ci.getBeginIndex();
        text = new char[ci.getEndIndex() - begin];
        int[] breaks0 = new int[text.length + 1];
        int brIx = 0;
        breaks0[brIx++] = begin;

        int charIx = 0;
        boolean inWs = false;
        for (char c = ci.first(); c != CharacterIterator.DONE; c = ci.next()) {
            text[charIx] = c;
            boolean ws = Character.isWhitespace(c);
            if (inWs && !ws) {
                breaks0[brIx++] = charIx + begin;
            }
            inWs = ws;
            charIx++;
        }
        if (text.length > 0) {
            breaks0[brIx++] = text.length + begin;
        }
        System.arraycopy(breaks0, 0, breaks = new int[brIx], 0, brIx);
    }

    public CharacterIterator getText() {
        return new StringCharacterIterator(new String(text));
    }

    public int first() {
        return breaks[pos = 0];
    }

    public int last() {
        return breaks[pos = breaks.length - 1];
    }

    public int current() {
        return breaks[pos];
    }

    public int next() {
        return (pos == breaks.length - 1 ? DONE : breaks[++pos]);
    }

    public int previous() {
        return (pos == 0 ? DONE : breaks[--pos]);
    }

    public int next(int n) {
        return checkhit(pos + n);
    }

    public int following(int n) {
        return adjacent(n, 1);
    }

    public int preceding(int n) {
        return adjacent(n, -1);
    }

    private int checkhit(int hit) {
        if ((hit < 0) || (hit >= breaks.length)) {
            return DONE;
        } else {
            return breaks[pos = hit];
        }
    }

    private int adjacent(int n, int bias) {
        int hit = Arrays.binarySearch(breaks, n);
        int offset = (hit < 0 ? (bias < 0 ? -1 : -2) : 0);
        return checkhit(Math.abs(hit) + bias + offset);
    }
}