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8159337: Introduce a method in Locale class to return the language tags as per RFC 5646 convention

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Reviewed-by: naoto, rriggs
This commit is contained in:
Justin Lu 2023-05-09 17:15:06 +00:00
parent 3aff5eacbd
commit 82bcee76ea
3 changed files with 276 additions and 5 deletions
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54
src/java.base/share/classes/java/util/Locale.java
View file

@ -1689,6 +1689,58 @@ public final class Locale implements Cloneable, Serializable {
return langTag;
}
/**
* {@return a case folded IETF BCP 47 language tag}
*
* <p>This method formats a language tag into one with case convention
* that adheres to section 2.1.1. Formatting of Language Tags of RFC5646.
* This format is defined as: <i>All subtags, including extension and private
* use subtags, use lowercase letters with two exceptions: two-letter
* and four-letter subtags that neither appear at the start of the tag
* nor occur after singletons. Such two-letter subtags are all
* uppercase (as in the tags "en-CA-x-ca" or "sgn-BE-FR") and four-
* letter subtags are titlecase (as in the tag "az-Latn-x-latn").</i> As
* legacy tags, (defined as "grandfathered" in RFC5646) are not always well-formed, this method
* will simply case fold a legacy tag to match the exact case convention
* for the particular tag specified in the respective
* {@link ##legacy_tags Legacy tags} table.
*
* <p><b>Special Exceptions</b>
* <p>To maintain consistency with {@link ##def_variant variant}
* which is case-sensitive, this method will neither case fold variant
* subtags nor case fold private use subtags prefixed by {@code lvariant}.
*
* <p>For example,
* {@snippet lang=java :
* String tag = "ja-kana-jp-x-lvariant-Oracle-JDK-Standard-Edition";
* Locale.caseFoldLanguageTag(tag); // returns "ja-Kana-JP-x-lvariant-Oracle-JDK-Standard-Edition"
* String tag2 = "ja-kana-jp-x-Oracle-JDK-Standard-Edition";
* Locale.caseFoldLanguageTag(tag2); // returns "ja-Kana-JP-x-oracle-jdk-standard-edition"
* }
*
* <p>Excluding case folding, this method makes no modifications to the tag itself.
* Case convention of language tags does not carry meaning, and is simply
* recommended as it corresponds with various ISO standards, including:
* ISO639-1, ISO15924, and ISO3166-1.
*
* <p>As the formatting of the case convention is dependent on the
* positioning of certain subtags, callers of this method should ensure
* that the language tag is well-formed, (conforming to section 2.1. Syntax
* of RFC5646).
*
* @param languageTag the IETF BCP 47 language tag.
* @throws IllformedLocaleException if {@code languageTag} is not well-formed
* @throws NullPointerException if {@code languageTag} is {@code null}
* @spec https://www.rfc-editor.org/rfc/rfc5646.html#section-2.1
* RFC5646 2.1. Syntax
* @spec https://www.rfc-editor.org/rfc/rfc5646#section-2.1.1
* RFC5646 2.1.1. Formatting of Language Tags
* @since 21
*/
public static String caseFoldLanguageTag(String languageTag) {
return LanguageTag.caseFoldTag(languageTag);
}
/**
* Returns a locale for the specified IETF BCP 47 language tag string.
*
@ -1748,7 +1800,7 @@ public final class Locale implements Cloneable, Serializable {
* // returns "th-TH-u-nu-thai-x-lvariant-TH"
* </pre></ul>
*
* <p>This implements the 'Language-Tag' production of BCP47, and
* <p id="legacy_tags">This implements the 'Language-Tag' production of BCP47, and
* so supports legacy (regular and irregular, referred to as
* "Type: grandfathered" in BCP47) as well as
* private use language tags. Stand alone private use tags are

55
src/java.base/share/classes/sun/util/locale/LanguageTag.java
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 2010, 2020, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2010, 2023, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -34,7 +34,9 @@ package sun.util.locale;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.IllformedLocaleException;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Set;
import java.util.StringJoiner;
@ -59,7 +61,6 @@ public class LanguageTag {
private List<String> extlangs = Collections.emptyList(); // extlang subtags
private List<String> variants = Collections.emptyList(); // variant subtags
private List<String> extensions = Collections.emptyList(); // extensions
// Map contains legacy language tags and its preferred mappings from
// http://www.ietf.org/rfc/rfc5646.txt
// Keys are lower-case strings.
@ -208,7 +209,6 @@ public class LanguageTag {
tag.parseExtensions(itr, sts);
}
tag.parsePrivateuse(itr, sts);
if (!itr.isDone() && !sts.isError()) {
String s = itr.current();
sts.errorIndex = itr.currentStart();
@ -218,7 +218,6 @@ public class LanguageTag {
sts.errorMsg = "Invalid subtag: " + s;
}
}
return tag;
}
@ -414,6 +413,54 @@ public class LanguageTag {
return found;
}
public static String caseFoldTag(String tag) {
ParseStatus sts = new ParseStatus();
parse(tag, sts);
// Illegal tags
if (sts.errorMsg != null) {
throw new IllformedLocaleException(String.format("Ill formed tag:" +
" %s", sts.errorMsg));
}
// Legacy tags
String potentialLegacy = tag.toLowerCase(Locale.ROOT);
if (LEGACY.containsKey(potentialLegacy)) {
return LEGACY.get(potentialLegacy)[0];
}
// Non-legacy tags
StringBuilder bldr = new StringBuilder(tag.length());
String[] subtags = tag.split("-");
boolean privateFound = false;
boolean singletonFound = false;
boolean privUseVarFound = false;
for (int i = 0; i < subtags.length; i++) {
String subtag = subtags[i];
if (privUseVarFound) {
bldr.append(subtag);
} else if (i > 0 && isVariant(subtag) && !singletonFound && !privateFound) {
bldr.append(subtag);
} else if (i > 0 && isRegion(subtag) && !singletonFound && !privateFound) {
bldr.append(canonicalizeRegion(subtag));
} else if (i > 0 && isScript(subtag) && !singletonFound && !privateFound) {
bldr.append(canonicalizeScript(subtag));
// If subtag is not 2 letter, 4 letter, or variant
// under the right conditions, then it should be lower-case
} else {
if (isPrivateusePrefix(subtag)) {
privateFound = true;
} else if (isExtensionSingleton(subtag)) {
singletonFound = true;
} else if (subtag.equals(PRIVUSE_VARIANT_PREFIX)) {
privUseVarFound = true;
}
bldr.append(subtag.toLowerCase(Locale.ROOT));
}
if (i != subtags.length-1) {
bldr.append("-");
}
}
return bldr.substring(0);
}
public static LanguageTag parseLocale(BaseLocale baseLocale, LocaleExtensions localeExtensions) {
LanguageTag tag = new LanguageTag();

172
test/jdk/java/util/Locale/CaseFoldLanguageTagTest.java Normal file
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@ -0,0 +1,172 @@
/*
* Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* @test
* @bug 8159337
* @summary Test Locale.caseFoldLanguageTag(String languageTag)
* @run junit CaseFoldLanguageTagTest
*/
import org.junit.jupiter.api.AfterAll;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertThrows;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.Arguments;
import org.junit.jupiter.params.provider.MethodSource;
import java.util.IllformedLocaleException;
import java.util.Locale;
import java.util.stream.Stream;
/**
* Test the implementation of Locale.caseFoldLanguageTag(String languageTag).
* A variety of well-formed tags are tested, composed of the following subtags:
* language, extlang, script, region, variant, extension, singleton, privateuse,
* grandfathered, and irregular. For more info, see the following,
* <a href="https://www.rfc-editor.org/rfc/rfc5646.html#section-2.1">Tag Syntax</a>).
* In addition, the method is tested to ensure that IllformedLocaleException and
* NullPointerException are thrown given the right circumstances.
*/
public class CaseFoldLanguageTagTest {
@ParameterizedTest
@MethodSource("wellFormedTags")
public void wellFormedTags(String tag, String foldedTag) {
assertEquals(foldedTag, Locale.caseFoldLanguageTag(tag), String.format("Folded %s", tag));
}
@ParameterizedTest
@MethodSource("illFormedTags")
public void illFormedTags(String tag) {
assertThrows(IllformedLocaleException.class, () ->
Locale.caseFoldLanguageTag(tag));
}
@Test
public void throwNPE() {
assertThrows(NullPointerException.class, () ->
Locale.caseFoldLanguageTag(null));
}
private static Stream<Arguments> wellFormedTags() {
return Stream.of(
// langtag tests
// language
Arguments.of("AB", "ab"),
// language - ext
Arguments.of("AB-ABC", "ab-abc"),
// language - ext - script
Arguments.of("AB-ABC-ABCD", "ab-abc-Abcd"),
// language - ext - script - region
Arguments.of("AB-ABC-ABCD-ab", "ab-abc-Abcd-AB"),
// language - region
Arguments.of("AB-ab", "ab-AB"),
// language - script
Arguments.of("AB-aBCD", "ab-Abcd"),
// language - private use
Arguments.of("AB-X-AB-ABCD", "ab-x-ab-abcd"),
// language - ext - script - region - variant
Arguments.of("AB-ABC-ABCD-ab-ABCDE", "ab-abc-Abcd-AB-ABCDE"),
// language - ext - script - region - variant x 2
Arguments.of("AB-ABC-ABCD-ab-ABCDE-fghij",
"ab-abc-Abcd-AB-ABCDE-fghij"),
// language - ext - script - region - variant - extension
Arguments.of("AB-ABC-ABCD-ab-ABCDE-A-ABCD",
"ab-abc-Abcd-AB-ABCDE-a-abcd"),
// language - ext - script - region - variant - private
Arguments.of("AB-ABC-ABCD-ab-ABCDE-X-ABCD",
"ab-abc-Abcd-AB-ABCDE-x-abcd"),
// language - ext - script - region - variant - extension x2
Arguments.of("AB-ABC-ABCD-ab-ABCDE-A-ABCD-B-EFGHI",
"ab-abc-Abcd-AB-ABCDE-a-abcd-b-efghi"),
// language - ext - script - region - variant - extension - private
Arguments.of("AB-ABC-ABCD-ab-ABCDE-A-ABCD-X-ABCD",
"ab-abc-Abcd-AB-ABCDE-a-abcd-x-abcd"),
// language - ext - script - region - variant x2 - extension x2 - private (x2 ext)
Arguments.of("AB-ABC-ABCD-ab-ABCDE-A-ABCD-X-ABCD-EFGHI",
"ab-abc-Abcd-AB-ABCDE-a-abcd-x-abcd-efghi"),
// language - variant x2 - extension x3 - private
Arguments.of("AB-aBcDeF-GhIjKl-a-ABC-DEFGH-B-ABC-C-ABC-X-A-ABC-DEF",
"ab-aBcDeF-GhIjKl-a-abc-defgh-b-abc-c-abc-x-a-abc-def"),
// language - ext- script - region - variant - extension x2 - private (x2 ext)
Arguments.of("AB-ABC-ABCD-ab-abCDe12-A-AB-B-ABCD-X-AB-ABCD",
"ab-abc-Abcd-AB-abCDe12-a-ab-b-abcd-x-ab-abcd"),
// Multiple singleton extensions
Arguments.of("AB-ABC-ABCD-ab-ABCDE-A-ABCD-GGG-ZZZ-B-EFGHI",
"ab-abc-Abcd-AB-ABCDE-a-abcd-ggg-zzz-b-efghi"),
// private use tests
Arguments.of("X-Abc", "x-abc"), // regular private
Arguments.of("X-A-ABC", "x-a-abc"), // private w/ extended (incl. 1)
Arguments.of("X-A-AB-Abcd", "x-a-ab-abcd"), // private w/ extended (incl. 1, 2, 4)
// Legacy tests
// irregular
Arguments.of("I-AMI", "i-ami"),
Arguments.of("EN-gb-OED", "en-GB-oed"),
Arguments.of("SGN-be-fr", "sgn-BE-FR"),
// regular
Arguments.of("NO-BOK", "no-bok"),
Arguments.of("CEL-GAULISH", "cel-gaulish"),
Arguments.of("ZH-MIN-NAN", "zh-min-nan"),
// Special JDK Cases (Variant and x-lvariant)
Arguments.of("de-POSIX-x-URP-lvariant-Abc-Def", "de-POSIX-x-urp-lvariant-Abc-Def"),
Arguments.of("JA-JPAN-JP-U-CA-JAPANESE-x-RANDOM-lvariant-JP",
"ja-Jpan-JP-u-ca-japanese-x-random-lvariant-JP"),
Arguments.of("ja-JP-u-ca-japanese-x-lvariant-JP", "ja-JP-u-ca-japanese-x-lvariant-JP"),
Arguments.of("XX-ABCD-yy-VARIANT-x-TEST-lvariant-JDK",
"xx-Abcd-YY-VARIANT-x-test-lvariant-JDK"),
Arguments.of("ja-kana-jp-x-lvariant-Oracle-JDK-Standard-Edition",
"ja-Kana-JP-x-lvariant-Oracle-JDK-Standard-Edition"),
Arguments.of("ja-kana-jp-x-Oracle-JDK-Standard-Edition",
"ja-Kana-JP-x-oracle-jdk-standard-edition"),
Arguments.of("ja-kana-jp-a-ABC-EFG-ZZZ-b-aaa-x-Oracle-JDK-Standard-Edition",
"ja-Kana-JP-a-abc-efg-zzz-b-aaa-x-oracle-jdk-standard-edition")
);
}
private static Stream<Arguments> illFormedTags() {
return Stream.of(
// Starts with non-language
Arguments.of("xabadadoo-me"),
// Starts with singleton
Arguments.of("a-abc"),
Arguments.of("a-singleton-en-us"),
// Hanging dash
Arguments.of("en-"),
// Double dash
Arguments.of("en--US"),
// Script before ext lang
Arguments.of("ab-Script-ext"),
// Region before ext lang
Arguments.of("ab-AB-ext"),
// Variants at start
Arguments.of("variant-first-ab")
);
}
}