    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 Apache 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     * Constructs a new instance.
    040     */
    041    public OctalUnescaper() {
    042        // empty
    043    }
    044
    045    /**
    046     * Checks if the given char is an octal digit. Octal digits are the character representations of the digits 0 to 7.
    047     * @param ch the char to check
    048     * @return true if the given char is the character representation of one of the digits from 0 to 7
    049     */
    050    private boolean isOctalDigit(final char ch) {
    051        return ch >= '0' && ch <= '7';
    052    }
    053
    054    /**
    055     * Checks if the given char is the character representation of one of the digit from 0 to 3.
    056     * @param ch the char to check
    057     * @return true if the given char is the character representation of one of the digits from 0 to 3
    058     */
    059    private boolean isZeroToThree(final char ch) {
    060        return ch >= '0' && ch <= '3';
    061    }
    062
    063    /**
    064     * {@inheritDoc}
    065     */
    066    @Override
    067    public int translate(final CharSequence input, final int index, final Writer out) throws IOException {
    068        final int remaining = input.length() - index - 1; // how many characters left, ignoring the first \
    069        final StringBuilder builder = new StringBuilder();
    070        if (input.charAt(index) == '\\' && remaining > 0 && isOctalDigit(input.charAt(index + 1)) ) {
    071            final int next = index + 1;
    072            final int next2 = index + 2;
    073            final int next3 = index + 3;
    074
    075            // we know this is good as we checked it in the if block above
    076            builder.append(input.charAt(next));
    077
    078            if (remaining > 1 && isOctalDigit(input.charAt(next2))) {
    079                builder.append(input.charAt(next2));
    080                if (remaining > 2 && isZeroToThree(input.charAt(next)) && isOctalDigit(input.charAt(next3))) {
    081                    builder.append(input.charAt(next3));
    082                }
    083            }
    084
    085            out.write( Integer.parseInt(builder.toString(), 8) );
    086            return 1 + builder.length();
    087        }
    088        return 0;
    089    }
    090}