001/*
002 * jPOS Project [http://jpos.org]
003 * Copyright (C) 2000-2026 jPOS Software SRL
004 *
005 * This program is free software: you can redistribute it and/or modify
006 * it under the terms of the GNU Affero General Public License as
007 * published by the Free Software Foundation, either version 3 of the
008 * License, or (at your option) any later version.
009 *
010 * This program is distributed in the hope that it will be useful,
011 * but WITHOUT ANY WARRANTY; without even the implied warranty of
012 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
013 * GNU Affero General Public License for more details.
014 *
015 * You should have received a copy of the GNU Affero General Public License
016 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
017 */
018
019package org.jpos.iso;
020
021
022/**
023 * Implements the Padder interface for padding strings and byte arrays on the
024 * left.
025 * 
026 * @author joconnor
027 * @version $Revision$ $Date$
028 */
029public class LeftPadder implements Padder
030{
031    /**
032         * A padder for padding zeros on the left. This is very common in numeric
033         * fields.
034         */
035    public static final LeftPadder ZERO_PADDER = new LeftPadder('0');
036
037    private char pad;
038
039    /**
040         * Creates a Left Padder with a specific pad character.
041         * 
042         * @param pad
043         *            The padding character. For binary padders, the pad character
044         *            is truncated to lower order byte.
045         */
046    public LeftPadder(char pad)
047    {
048        this.pad = pad;
049    }
050
051    /**
052     */
053    public String pad(String data, int maxLength) throws ISOException
054    {
055        StringBuilder padded = new StringBuilder(maxLength);
056        int len = data.length();
057        if (len > maxLength)
058        {
059            throw new ISOException("Data is too long. Max = " + maxLength);
060        } else
061        {
062            for (int i = maxLength - len; i > 0; i--)
063            {
064                padded.append(pad);
065            }
066            padded.append(data);
067        }
068        return padded.toString();
069    }
070
071    /**
072         * (non-Javadoc)
073         *
074     */
075    public String unpad(String paddedData)
076    {
077        int i = 0;
078        int len = paddedData.length();
079        while (i < len)
080        {
081            if (paddedData.charAt(i) != pad)
082            {
083                return paddedData.substring(i);
084            }
085            i++;
086        }
087        return "";
088    }
089}