| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.commons.text.translate; |
| |
| import java.io.IOException; |
| import java.io.Writer; |
| |
| /** |
| * Translate escaped octal Strings back to their octal values. |
| * |
| * For example, "\45" should go back to being the specific value (a %). |
| * |
| * Note that this currently only supports the viable range of octal for Java; namely |
| * 1 to 377. This is because parsing Java is the main use case. |
| * |
| * @since 1.0 |
| */ |
| public class OctalUnescaper extends CharSequenceTranslator { |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public int translate(final CharSequence input, final int index, final Writer out) throws IOException { |
| final int remaining = input.length() - index - 1; // how many characters left, ignoring the first \ |
| final StringBuilder builder = new StringBuilder(); |
| if (input.charAt(index) == '\\' && remaining > 0 && isOctalDigit(input.charAt(index + 1))) { |
| final int next = index + 1; |
| final int next2 = index + 2; |
| final int next3 = index + 3; |
| |
| // we know this is good as we checked it in the if block above |
| builder.append(input.charAt(next)); |
| |
| if (remaining > 1 && isOctalDigit(input.charAt(next2))) { |
| builder.append(input.charAt(next2)); |
| if (remaining > 2 && isZeroToThree(input.charAt(next)) && isOctalDigit(input.charAt(next3))) { |
| builder.append(input.charAt(next3)); |
| } |
| } |
| |
| out.write(Integer.parseInt(builder.toString(), 8)); |
| return 1 + builder.length(); |
| } |
| return 0; |
| } |
| |
| /** |
| * Checks if the given char is an octal digit. Octal digits are the character representations of the digits 0 to 7. |
| * @param ch the char to check |
| * @return true if the given char is the character representation of one of the digits from 0 to 7 |
| */ |
| private boolean isOctalDigit(final char ch) { |
| return ch >= '0' && ch <= '7'; |
| } |
| |
| /** |
| * Checks if the given char is the character representation of one of the digit from 0 to 3. |
| * @param ch the char to check |
| * @return true if the given char is the character representation of one of the digits from 0 to 3 |
| */ |
| private boolean isZeroToThree(final char ch) { |
| return ch >= '0' && ch <= '3'; |
| } |
| } |