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 */
017package org.apache.commons.lang3.text.translate;
018
019import java.io.IOException;
020import 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 because parsing Java is the main use case.
029 *
030 * @since 3.0
031 * @deprecated as of 3.6, use commons-text
032 * <a href="https://commons.apache.org/proper/commons-text/javadocs/api-release/org/apache/commons/text/translate/OctalUnescaper.html">
033 * OctalUnescaper</a> instead
034 */
035@Deprecated
036public class OctalUnescaper extends CharSequenceTranslator {
037
038    /**
039     * {@inheritDoc}
040     */
041    @Override
042    public int translate(final CharSequence input, final int index, final Writer out) throws IOException {
043        final int remaining = input.length() - index - 1; // how many characters left, ignoring the first \
044        final StringBuilder builder = new StringBuilder();
045        if (input.charAt(index) == '\\' && remaining > 0 && isOctalDigit(input.charAt(index + 1)) ) {
046            final int next = index + 1;
047            final int next2 = index + 2;
048            final int next3 = index + 3;
049
050            // we know this is good as we checked it in the if block above
051            builder.append(input.charAt(next));
052
053            if (remaining > 1 && isOctalDigit(input.charAt(next2))) {
054                builder.append(input.charAt(next2));
055                if (remaining > 2 && isZeroToThree(input.charAt(next)) && isOctalDigit(input.charAt(next3))) {
056                    builder.append(input.charAt(next3));
057                }
058            }
059
060            out.write( Integer.parseInt(builder.toString(), 8) );
061            return 1 + builder.length();
062        }
063        return 0;
064    }
065
066    /**
067     * Checks if the given char is an octal digit. Octal digits are the character representations of the digits 0 to 7.
068     * @param ch the char to check
069     * @return true if the given char is the character representation of one of the digits from 0 to 7
070     */
071    private boolean isOctalDigit(final char ch) {
072        return ch >= '0' && ch <= '7';
073    }
074
075    /**
076     * Checks if the given char is the character representation of one of the digit from 0 to 3.
077     * @param ch the char to check
078     * @return true if the given char is the character representation of one of the digits from 0 to 3
079     */
080    private boolean isZeroToThree(final char ch) {
081        return ch >= '0' && ch <= '3';
082    }
083}