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 */
017 package org.apache.commons.lang3.text.translate;
018
019 import java.io.IOException;
020 import java.io.Writer;
021 import java.util.Arrays;
022 import java.util.EnumSet;
023
024 /**
025 * Translate XML numeric entities of the form &#[xX]?\d+;? to
026 * the specific codepoint.
027 *
028 * Note that the semi-colon is optional.
029 *
030 * @since 3.0
031 * @version $Id: NumericEntityUnescaper.java 1199894 2011-11-09 17:53:59Z ggregory $
032 */
033 public class NumericEntityUnescaper extends CharSequenceTranslator {
034
035 public static enum OPTION { semiColonRequired, semiColonOptional, errorIfNoSemiColon }
036
037 // TODO?: Create an OptionsSet class to hide some of the conditional logic below
038 private final EnumSet<OPTION> options;
039
040 /**
041 * Create a UnicodeUnescaper.
042 *
043 * The constructor takes a list of options, only one type of which is currently
044 * available (whether to allow, error or ignore the semi-colon on the end of a
045 * numeric entity to being missing).
046 *
047 * For example, to support numeric entities without a ';':
048 * new NumericEntityUnescaper(NumericEntityUnescaper.OPTION.semiColonOptional)
049 * and to throw an IllegalArgumentException when they're missing:
050 * new NumericEntityUnescaper(NumericEntityUnescaper.OPTION.errorIfNoSemiColon)
051 *
052 * Note that the default behaviour is to ignore them.
053 *
054 * @param options to apply to this unescaper
055 */
056 public NumericEntityUnescaper(OPTION... options) {
057 if(options.length > 0) {
058 this.options = EnumSet.copyOf(Arrays.asList(options));
059 } else {
060 this.options = EnumSet.copyOf(Arrays.asList(new OPTION[] { OPTION.semiColonRequired }));
061 }
062 }
063
064 /**
065 * Whether the passed in option is currently set.
066 *
067 * @param option to check state of
068 * @return whether the option is set
069 */
070 public boolean isSet(OPTION option) {
071 return options == null ? false : options.contains(option);
072 }
073
074 /**
075 * {@inheritDoc}
076 */
077 @Override
078 public int translate(CharSequence input, int index, Writer out) throws IOException {
079 int seqEnd = input.length();
080 // Uses -2 to ensure there is something after the &#
081 if(input.charAt(index) == '&' && index < seqEnd - 2 && input.charAt(index + 1) == '#') {
082 int start = index + 2;
083 boolean isHex = false;
084
085 char firstChar = input.charAt(start);
086 if(firstChar == 'x' || firstChar == 'X') {
087 start++;
088 isHex = true;
089
090 // Check there's more than just an x after the &#
091 if(start == seqEnd) {
092 return 0;
093 }
094 }
095
096 int end = start;
097 // Note that this supports character codes without a ; on the end
098 while(end < seqEnd && ( input.charAt(end) >= '0' && input.charAt(end) <= '9' ||
099 input.charAt(end) >= 'a' && input.charAt(end) <= 'f' ||
100 input.charAt(end) >= 'A' && input.charAt(end) <= 'F' ) )
101 {
102 end++;
103 }
104
105 boolean semiNext = end != seqEnd && input.charAt(end) == ';';
106
107 if(!semiNext) {
108 if(isSet(OPTION.semiColonRequired)) {
109 return 0;
110 } else
111 if(isSet(OPTION.errorIfNoSemiColon)) {
112 throw new IllegalArgumentException("Semi-colon required at end of numeric entity");
113 }
114 }
115
116 int entityValue;
117 try {
118 if(isHex) {
119 entityValue = Integer.parseInt(input.subSequence(start, end).toString(), 16);
120 } else {
121 entityValue = Integer.parseInt(input.subSequence(start, end).toString(), 10);
122 }
123 } catch(NumberFormatException nfe) {
124 return 0;
125 }
126
127 if(entityValue > 0xFFFF) {
128 char[] chrs = Character.toChars(entityValue);
129 out.write(chrs[0]);
130 out.write(chrs[1]);
131 } else {
132 out.write(entityValue);
133 }
134
135 return 2 + end - start + (isHex ? 1 : 0) + (semiNext ? 1 : 0);
136 }
137 return 0;
138 }
139 }