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 *      https://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 */
017package org.apache.commons.lang3.text.translate;
018
019import java.io.IOException;
020import java.io.Writer;
021
022import org.apache.commons.lang3.CharUtils;
023
024/**
025 * Translate escaped octal Strings back to their octal values.
026 *
027 * For example, "\45" should go back to being the specific value (a %).
028 *
029 * Note that this currently only supports the viable range of octal for Java; namely
030 * 1 to 377. This is because parsing Java is the main use case.
031 *
032 * @since 3.0
033 * @deprecated As of <a href="https://commons.apache.org/proper/commons-lang/changes-report.html#a3.6">3.6</a>, use Apache Commons Text
034 * <a href="https://commons.apache.org/proper/commons-text/javadocs/api-release/org/apache/commons/text/translate/OctalUnescaper.html">
035 * OctalUnescaper</a>.
036 */
037@Deprecated
038public class OctalUnescaper extends CharSequenceTranslator {
039
040    /**
041     * Constructs a new instance.
042     */
043    public OctalUnescaper() {
044        // empty
045    }
046
047    /**
048     * Checks if the given char is the character representation of one of the digit from 0 to 3.
049     * @param ch the char to check
050     * @return true if the given char is the character representation of one of the digits from 0 to 3
051     */
052    private boolean isZeroToThree(final char ch) {
053        return ch >= '0' && ch <= '3';
054    }
055
056    /**
057     * {@inheritDoc}
058     */
059    @Override
060    public int translate(final CharSequence input, final int index, final Writer out) throws IOException {
061        final int remaining = input.length() - index - 1; // how many characters left, ignoring the first \
062        final StringBuilder builder = new StringBuilder();
063        if (input.charAt(index) == '\\' && remaining > 0 && CharUtils.isOctal(input.charAt(index + 1))) {
064            final int next = index + 1;
065            final int next2 = index + 2;
066            final int next3 = index + 3;
067            // we know this is good as we checked it in the if block above
068            builder.append(input.charAt(next));
069            if (remaining > 1 && CharUtils.isOctal(input.charAt(next2))) {
070                builder.append(input.charAt(next2));
071                if (remaining > 2 && isZeroToThree(input.charAt(next)) && CharUtils.isOctal(input.charAt(next3))) {
072                    builder.append(input.charAt(next3));
073                }
074            }
075            out.write(Integer.parseInt(builder.toString(), 8));
076            return 1 + builder.length();
077        }
078        return 0;
079    }
080}