    001    /*
    002     * Licensed to the Apache Software Foundation (ASF) under one or more
    003     * contributor license agreements.  See the NOTICE file distributed with
    004     * this work for additional information regarding copyright ownership.
    005     * The ASF licenses this file to You under the Apache License, Version 2.0
    006     * (the "License"); you may not use this file except in compliance with
    007     * the License.  You may obtain a copy of the License at
    008     *
    009     *      http://www.apache.org/licenses/LICENSE-2.0
    010     *
    011     * Unless required by applicable law or agreed to in writing, software
    012     * distributed under the License is distributed on an "AS IS" BASIS,
    013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014     * See the License for the specific language governing permissions and
    015     * limitations under the License.
    016     */
    017    package org.apache.commons.lang3.text.translate;
    018
    019    import java.io.IOException;
    020    import java.io.Writer;
    021
    022    /**
    023     * Translate escaped octal Strings back to their octal values.
    024     *
    025     * For example, "\45" should go back to being the specific value (a %).
    026     *
    027     * Note that this currently only supports the viable range of octal for Java; namely
    028     * 1 to 377. This is both because parsing Java is the main use case and Integer.parseInt
    029     * throws an exception when values are larger than octal 377.
    030     *
    031     * @since 3.0
    032     * @version $Id: OctalUnescaper.java 967237 2010-07-23 20:08:57Z mbenson $
    033     */
    034    public class OctalUnescaper extends CharSequenceTranslator {
    035
    036        private static int OCTAL_MAX = 377;
    037
    038        /**
    039         * {@inheritDoc}
    040         */
    041        @Override
    042        public int translate(CharSequence input, int index, Writer out) throws IOException {
    043            if(input.charAt(index) == '\\' && index < (input.length() - 1) && Character.isDigit(input.charAt(index + 1)) ) {
    044                int start = index + 1;
    045
    046                int end = index + 2;
    047                while ( end < input.length() && Character.isDigit(input.charAt(end)) ) {
    048                    end++;
    049                    if ( Integer.parseInt(input.subSequence(start, end).toString(), 10) > OCTAL_MAX) {
    050                        end--; // rollback
    051                        break;
    052                    }
    053                }
    054
    055                out.write( Integer.parseInt(input.subSequence(start, end).toString(), 8) );
    056                return 1 + end - start;
    057            }
    058            return 0;
    059        }
    060    }