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Utils: Don't truncate at a ZWJ

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zzz
2018-07-25 15:34:23 +00:00
parent a6c506a176
commit 41e20ae707
1 changed files with 10 additions and 4 deletions
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14
apps/jetty/java/src/net/i2p/servlet/util/ServletUtil.java
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@@ -65,19 +65,25 @@ public class ServletUtil {
/**
* Truncate a String.
* Same as s.substring(0, len) except that
* it won't split a surrogate pair.
* it won't split a surrogate pair or at a ZWJ.
*
* @param s non-null
* @param len greater than zero
* @return s if shorter; s.substring(0, len) if
* the char at len-1 is not a high surrogate;
* s.substring(0, len+1) if it is
* the char at len-1 is not a high surrogate
* or the char at len-1 or len is not a zero-width joiner;
* s.substring(0, len+1 or len+2) if it is
* @since 0.9.33
*/
public static String truncate(String s, int len) {
if (s.length() <= len)
return s;
if (Character.isHighSurrogate(s.charAt(len - 1)))
char c = s.charAt(len - 1);
// https://en.wikipedia.org/wiki/Zero-width_joiner
if (Character.isHighSurrogate(c) || c == 0x200D)
return s.substring(0, len + 1);
if (s.charAt(len) == 0x200D)
return s.substring(0, len + 2);
return s.substring(0, len);
}
}