1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.text.translate;
18
19 import java.io.IOException;
20 import java.io.Writer;
21 import java.util.Arrays;
22 import java.util.EnumSet;
23
24 /**
25 * Translate XML numeric entities of the form &#[xX]?\d+;? to
26 * the specific codepoint.
27 *
28 * Note that the semi-colon is optional.
29 *
30 * @since 1.0
31 */
32 public class NumericEntityUnescaper extends CharSequenceTranslator {
33
34 public static enum OPTION { semiColonRequired, semiColonOptional, errorIfNoSemiColon }
35
36 // TODO?: Create an OptionsSet class to hide some of the conditional logic below
37 private final EnumSet<OPTION> options;
38
39 /**
40 * Create a UnicodeUnescaper.
41 *
42 * The constructor takes a list of options, only one type of which is currently
43 * available (whether to allow, error or ignore the semi-colon on the end of a
44 * numeric entity to being missing).
45 *
46 * For example, to support numeric entities without a ';':
47 * new NumericEntityUnescaper(NumericEntityUnescaper.OPTION.semiColonOptional)
48 * and to throw an IllegalArgumentException when they're missing:
49 * new NumericEntityUnescaper(NumericEntityUnescaper.OPTION.errorIfNoSemiColon)
50 *
51 * Note that the default behaviour is to ignore them.
52 *
53 * @param options to apply to this unescaper
54 */
55 public NumericEntityUnescaper(final OPTION... options) {
56 if(options.length > 0) {
57 this.options = EnumSet.copyOf(Arrays.asList(options));
58 } else {
59 this.options = EnumSet.copyOf(Arrays.asList(new OPTION[] { OPTION.semiColonRequired }));
60 }
61 }
62
63 /**
64 * Whether the passed in option is currently set.
65 *
66 * @param option to check state of
67 * @return whether the option is set
68 */
69 public boolean isSet(final OPTION option) {
70 return options == null ? false : options.contains(option);
71 }
72
73 /**
74 * {@inheritDoc}
75 */
76 @Override
77 public int translate(final CharSequence input, final int index, final Writer out) throws IOException {
78 final int seqEnd = input.length();
79 // Uses -2 to ensure there is something after the &#
80 if(input.charAt(index) == '&' && index < seqEnd - 2 && input.charAt(index + 1) == '#') {
81 int start = index + 2;
82 boolean isHex = false;
83
84 final char firstChar = input.charAt(start);
85 if(firstChar == 'x' || firstChar == 'X') {
86 start++;
87 isHex = true;
88
89 // Check there's more than just an x after the &#
90 if(start == seqEnd) {
91 return 0;
92 }
93 }
94
95 int end = start;
96 // Note that this supports character codes without a ; on the end
97 while(end < seqEnd && ( input.charAt(end) >= '0' && input.charAt(end) <= '9' ||
98 input.charAt(end) >= 'a' && input.charAt(end) <= 'f' ||
99 input.charAt(end) >= 'A' && input.charAt(end) <= 'F' ) )
100 {
101 end++;
102 }
103
104 final boolean semiNext = end != seqEnd && input.charAt(end) == ';';
105
106 if(!semiNext) {
107 if(isSet(OPTION.semiColonRequired)) {
108 return 0;
109 } else
110 if(isSet(OPTION.errorIfNoSemiColon)) {
111 throw new IllegalArgumentException("Semi-colon required at end of numeric entity");
112 }
113 }
114
115 int entityValue;
116 try {
117 if(isHex) {
118 entityValue = Integer.parseInt(input.subSequence(start, end).toString(), 16);
119 } else {
120 entityValue = Integer.parseInt(input.subSequence(start, end).toString(), 10);
121 }
122 } catch(final NumberFormatException nfe) {
123 return 0;
124 }
125
126 if(entityValue > 0xFFFF) {
127 final char[] chrs = Character.toChars(entityValue);
128 out.write(chrs[0]);
129 out.write(chrs[1]);
130 } else {
131 out.write(entityValue);
132 }
133
134 return 2 + end - start + (isHex ? 1 : 0) + (semiNext ? 1 : 0);
135 }
136 return 0;
137 }
138 }