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ICU-21567 Avoid using regex in ULocale.getName()

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No behavior change is expected
This commit is contained in:
Victor Chang 2021-03-29 23:52:43 +01:00 • committed by Fredrik Roubert
parent b13be666cd
commit fa4c12cdc2
1 changed files with 31 additions and 4 deletions
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35
icu4j/main/classes/core/src/com/ibm/icu/util/ULocale.java
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@ -28,7 +28,6 @@ import java.util.Objects;
import java.util.Set;
import java.util.TreeMap;
import java.util.TreeSet;
import java.util.regex.Pattern;
import com.ibm.icu.impl.CacheBase;
import com.ibm.icu.impl.ICUData;
@ -119,8 +118,6 @@ public final class ULocale implements Serializable, Comparable<ULocale> {
// using serialver from jdk1.4.2_05
private static final long serialVersionUID = 3715177670352309217L;
private static final Pattern UND_PATTERN = Pattern.compile("^und(?=$|[_-])", Pattern.CASE_INSENSITIVE);
private static CacheBase<String, String, Void> nameCache = new SoftCache<String, String, Void>() {
@Override
protected String createInstance(String tmpLocaleID, Void unused) {
@ -1144,11 +1141,41 @@ public final class ULocale implements Serializable, Comparable<ULocale> {
} else if ("root".equalsIgnoreCase(localeID)) {
tmpLocaleID = EMPTY_STRING;
} else {
tmpLocaleID = UND_PATTERN.matcher(localeID).replaceFirst(EMPTY_STRING);
tmpLocaleID = stripLeadingUnd(localeID);
}
return nameCache.getInstance(tmpLocaleID, null /* unused */);
}
/**
* Strips out the leading "und" language code case-insensitively.
*
* @implNote Avoids creating new local non-primitive objects to reduce GC pressure.
*/
private static String stripLeadingUnd(String localeID) {
int length = localeID.length();
if (length < 3) {
return localeID;
}
// If not starts with "und", return.
if (!localeID.regionMatches(/*ignoreCase=*/true, 0, "und", 0, /*len=*/3)) {
return localeID;
}
// The string is equals to "und" case-insensitively.
if (length == 3) {
return EMPTY_STRING;
}
// localeID must have a length >= 4
char separator = localeID.charAt(3);
if (separator == '-' || separator == '_') { // "und-*" or "und_*"
return localeID.substring(3);
}
return localeID;
}
/**
* Returns a string representation of this object.
* @return a string representation of the object.