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The Archive Commons Code Libraries project contains general Java utility libraries, as used by the Heritrix crawler and other projects.
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/*
 *  This file is part of the Heritrix web crawler (crawler.archive.org).
 *
 *  Licensed to the Internet Archive (IA) by one or more individual 
 *  contributors. 
 *
 *  The IA licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.archive.util;

/**
 * StringBuffer-like utility which can add spaces to reach a certain column.  It
 * allows you to append {@link String}, long and ints
 * to the buffer.
 * 
 * Note: This class counts from 1, not 0.
 * 

 * It uses a StringBuffer behind the scenes.
 * 
 * To write a string with multiple lines, it is advisible to use the
 * {@link #newline() newline()} function. Regular appending of strings with
 * newlines (\n) character should be safe though. Right appending of strings
 * with such characters is not safe.
 *
 * @author Gordon Mohr
 */
public final class PaddingStringBuffer {
    // The buffer.
    protected StringBuffer buffer;
    // Location in current line
    protected int linePos;

    /** 
     * Create a new PaddingStringBuffer
     *
     */
    public PaddingStringBuffer() {
        buffer = new StringBuffer();
        linePos=0;
    }

    /** append a string directly to the buffer
     * @param string the string to append
     * @return This wrapped buffer w/ the passed string appended.
     */
    public PaddingStringBuffer append(String string) {
        buffer.append(string);
        if ( string.indexOf('\n') == -1 ){
            linePos+=string.length();
        } else {
            while ( string.indexOf('\n') == -1 ){
                string = string.substring(string.indexOf('\n'));
            }
            linePos=string.length();
        }
        return this;
    }

    /**
     * Append a string, right-aligned to the given columm.  If the buffer
     * length is already greater than the column specified, it simply appends
     * the string
     *
     * @param col the column to right-align to
     * @param string the string, must not contain multiple lines.
     * @return This wrapped buffer w/ append string, right-aligned to the
     * given column.
     */
    public PaddingStringBuffer raAppend(int col, String string) {
        padTo(col-string.length());
        append(string);
        return this;
    }

    /** Pad to a given column.  If the buffer size is already greater than the
     * column, nothing is done.
     * @param col
     * @return The buffer padded to i.
     */
    public PaddingStringBuffer padTo(int col) {
        while(linePosint to the buffer.
     * @param i the int to append
     * @return This wrapped buffer with i appended.
     */
    public PaddingStringBuffer append(int i) {
        append(Integer.toString(i));
        return this;
    }


    /**
     * Append an int right-aligned to the given column.  If the
     * buffer length is already greater than the column specified, it simply
     * appends the int.
     *
     * @param col the column to right-align to
     * @param i   the int to append
     * @return This wrapped buffer w/ appended int, right-aligned to the
     *         given column.
     */
    public PaddingStringBuffer raAppend(int col, int i) {
        return raAppend(col,Integer.toString(i));
    }

    /** append a long to the buffer.
     * @param lo the long to append
     * @return This wrapped buffer w/ appended long.
     */
    public PaddingStringBuffer append(long lo) {
        append(Long.toString(lo));
        return this;
    }

    /**Append a long, right-aligned to the given column.  If the
     * buffer length is already greater than the column specified, it simply
     * appends the long.
     * @param col the column to right-align to
     * @param lo the long to append
     * @return This wrapped buffer w/ appended long, right-aligned to the
     * given column.
     */
    public PaddingStringBuffer raAppend(int col, long lo) {
        return raAppend(col,Long.toString(lo));
    }

    /** reset the buffer back to empty */
    public void reset() {
        buffer = new StringBuffer();
        linePos = 0;
    }

    /* (non-Javadoc)
     * @see java.lang.Object#toString()
     */
    public String toString() {
        return buffer.toString();
    }

    /**
     * Forces a new line in the buffer.
     */
    public PaddingStringBuffer newline() {
        buffer.append("\n");
        linePos = 0;
        return this;
    }

}