| /* |
| * 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; |
| |
| /** |
| * Translates escaped Unicode values of the form \\u+\d\d\d\d back to |
| * Unicode. It supports multiple 'u' characters and will work with or |
| * without the +. |
| * |
| * @since 1.0 |
| */ |
| public class UnicodeUnescaper extends CharSequenceTranslator { |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public int translate(final CharSequence input, final int index, final Writer out) throws IOException { |
| if (input.charAt(index) == '\\' && index + 1 < input.length() && input.charAt(index + 1) == 'u') { |
| // consume optional additional 'u' chars |
| int i = 2; |
| while (index + i < input.length() && input.charAt(index + i) == 'u') { |
| i++; |
| } |
| |
| if (index + i < input.length() && input.charAt(index + i) == '+') { |
| i++; |
| } |
| |
| if (index + i + 4 <= input.length()) { |
| // Get 4 hex digits |
| final CharSequence unicode = input.subSequence(index + i, index + i + 4); |
| |
| try { |
| final int value = Integer.parseInt(unicode.toString(), 16); |
| out.write((char) value); |
| } catch (final NumberFormatException nfe) { |
| throw new IllegalArgumentException("Unable to parse unicode value: " + unicode, nfe); |
| } |
| return i + 4; |
| } |
| throw new IllegalArgumentException("Less than 4 hex digits in unicode value: '" |
| + input.subSequence(index, input.length()) |
| + "' due to end of CharSequence"); |
| } |
| return 0; |
| } |
| } |