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 * @version $Id: OctalUnescaper.java 967237 2010-07-23 20:08:57Z mbenson $ 032 */ 033public class OctalUnescaper extends CharSequenceTranslator { 034 035 /** 036 * {@inheritDoc} 037 */ 038 @Override 039 public int translate(final CharSequence input, final int index, final Writer out) throws IOException { 040 int remaining = input.length() - index - 1; // how many characters left, ignoring the first \ 041 StringBuilder builder = new StringBuilder(); 042 if(input.charAt(index) == '\\' && remaining > 0 && isOctalDigit(input.charAt(index + 1)) ) { 043 int next = index + 1; 044 int next2 = index + 2; 045 int next3 = index + 3; 046 047 // we know this is good as we checked it in the if block above 048 builder.append(input.charAt(next)); 049 050 if(remaining > 1 && isOctalDigit(input.charAt(next2))) { 051 builder.append(input.charAt(next2)); 052 if(remaining > 2 && isZeroToThree(input.charAt(next)) && isOctalDigit(input.charAt(next3))) { 053 builder.append(input.charAt(next3)); 054 } 055 } 056 057 out.write( Integer.parseInt(builder.toString(), 8) ); 058 return 1 + builder.length(); 059 } 060 return 0; 061 } 062 063 /** 064 * Checks if the given char is an octal digit. Octal digits are the character representations of the digits 0 to 7. 065 * @param ch the char to check 066 * @return true if the given char is the character representation of one of the digits from 0 to 7 067 */ 068 private boolean isOctalDigit(char ch) { 069 return ch >= '0' && ch <= '7'; 070 } 071 072 /** 073 * Checks if the given char is the character representation of one of the digit from 0 to 3. 074 * @param ch the char to check 075 * @return true if the given char is the character representation of one of the digits from 0 to 3 076 */ 077 private boolean isZeroToThree(char ch) { 078 return ch >= '0' && ch <= '3'; 079 } 080}