Logback: the reliable, generic, fast and flexible logging framework.
Copyright (C) 1999-2015, QOS.ch. All rights reserved.
This program and the accompanying materials are dual-licensed under
either the terms of the Eclipse Public License v1.0 as published by
the Eclipse Foundation
  or (per the licensee's choosing)
under the terms of the GNU Lesser General Public License version 2.1
as published by the Free Software Foundation.
/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
 *
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *
 *   or (per the licensee's choosing)
 *
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 */
package ch.qos.logback.core.pattern;

public class SpacePadder {

    final static String[] SPACES = { " ", "  ", "    ", "        ", // 1,2,4,8
            // spaces
            "                ", // 16 spaces
            "                                " }; // 32 spaces

    final static public void leftPad(StringBuilder buf, String s, int desiredLength) {
        int actualLen = 0;
        if (s != null) {
            actualLen = s.length();
        }
        if (actualLen < desiredLength) {
            spacePad(buf, desiredLength - actualLen);
        }
        if (s != null) {
            buf.append(s);
        }
    }

    final static public void rightPad(StringBuilder buf, String s, int desiredLength) {
        int actualLen = 0;
        if (s != null) {
            actualLen = s.length();
        }
        if (s != null) {
            buf.append(s);
        }
        if (actualLen < desiredLength) {
            spacePad(buf, desiredLength - actualLen);
        }
    }

    
Fast space padding method.
/**
     * Fast space padding method.
     */
    final static public void spacePad(StringBuilder sbuf, int length) {
        while (length >= 32) {
            sbuf.append(SPACES[5]);
            length -= 32;
        }

        for (int i = 4; i >= 0; i--) {
            if ((length & (1 << i)) != 0) {
                sbuf.append(SPACES[i]);
            }
        }
    }
}