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17 package org.apache.commons.text.translate;
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19 import java.io.IOException;
20 import java.io.Writer;
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29 public class UnicodeUnescaper extends CharSequenceTranslator {
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34 public UnicodeUnescaper() {
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36 }
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41 @Override
42 public int translate(final CharSequence input, final int index, final Writer writer) throws IOException {
43 if (input.charAt(index) == '\\' && index + 1 < input.length() && input.charAt(index + 1) == 'u') {
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45 int i = 2;
46 while (index + i < input.length() && input.charAt(index + i) == 'u') {
47 i++;
48 }
49
50 if (index + i < input.length() && input.charAt(index + i) == '+') {
51 i++;
52 }
53
54 if (index + i + 4 <= input.length()) {
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56 final CharSequence unicode = input.subSequence(index + i, index + i + 4);
57
58 try {
59 final int value = Integer.parseInt(unicode.toString(), 16);
60 writer.write((char) value);
61 } catch (final NumberFormatException nfe) {
62 throw new IllegalArgumentException("Unable to parse unicode value: " + unicode, nfe);
63 }
64 return i + 4;
65 }
66 throw new IllegalArgumentException("Less than 4 hex digits in unicode value: '"
67 + input.subSequence(index, input.length())
68 + "' due to end of CharSequence");
69 }
70 return 0;
71 }
72 }