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/*
* Copyright (c) 1997, 2025, 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. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* 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.
*/
/*
* (C) Copyright Taligent, Inc. 1996-1998 - All Rights Reserved
* (C) Copyright IBM Corp. 1996-1998 - All Rights Reserved
*
* The original version of this source code and documentation is copyrighted
* and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These
* materials are provided under terms of a License Agreement between Taligent
* and Sun. This technology is protected by multiple US and International
* patents. This notice and attribution to Taligent may not be removed.
* Taligent is a registered trademark of Taligent, Inc.
*
*/
package java.text;
import java.lang.ref.SoftReference;
import java.text.spi.CollatorProvider;
import java.util.Locale;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import sun.util.locale.provider.LocaleProviderAdapter;
import sun.util.locale.provider.LocaleServiceProviderPool;
/**
* The {@code Collator} class performs locale-sensitive
* {@code String} comparison. You use this class to build
* searching and sorting routines for natural language text.
*
* <p>
* {@code Collator} is an abstract base class. Subclasses
* implement specific collation strategies. One subclass,
* {@code RuleBasedCollator}, is currently provided with
* the Java Platform and is applicable to a wide set of languages. Other
* subclasses may be created to handle more specialized needs.
*
* <p>
* Like other locale-sensitive classes, you can use the static
* factory method, {@code getInstance}, to obtain the appropriate
* {@code Collator} object for a given locale. You will only need
* to look at the subclasses of {@code Collator} if you need
* to understand the details of a particular collation strategy or
* if you need to modify that strategy.
*
* <p>
* The following example shows how to compare two strings using
* the {@code Collator} for the default locale.
* {@snippet lang=java :
* // Compare two strings in the default locale
* Collator myCollator = Collator.getInstance();
* if (myCollator.compare("abc", "ABC") < 0) {
* System.out.println("abc is less than ABC");
* } else {
* System.out.println("abc is greater than or equal to ABC");
* }
* }
*
* <p>
* You can set a {@code Collator}'s <em>strength</em> property
* to determine the level of difference considered significant in
* comparisons. Four strengths are provided: {@code PRIMARY},
* {@code SECONDARY}, {@code TERTIARY}, and {@code IDENTICAL}.
* The exact assignment of strengths to language features is
* locale dependent. For example, in Czech, "e" and "f" are considered
* primary differences, while "e" and "ě" are secondary differences,
* "e" and "E" are tertiary differences and "e" and "e" are identical.
* The following shows how both case and accents could be ignored for
* US English.
* {@snippet lang=java :
* // Get the Collator for US English and set its strength to PRIMARY
* Collator usCollator = Collator.getInstance(Locale.US);
* usCollator.setStrength(Collator.PRIMARY);
* if (usCollator.compare("abc", "ABC") == 0) {
* System.out.println("Strings are equivalent");
* }
* }
* <p>
* For comparing {@code String}s exactly once, the {@code compare}
* method provides the best performance. When sorting a list of
* {@code String}s however, it is generally necessary to compare each
* {@code String} multiple times. In this case, {@code CollationKey}s
* provide better performance. The {@code CollationKey} class converts
* a {@code String} to a series of bits that can be compared bitwise
* against other {@code CollationKey}s. A {@code CollationKey} is
* created by a {@code Collator} object for a given {@code String}.
* <br>
* @apiNote {@code CollationKey}s from different
* {@code Collator}s can not be compared. See the class description
* for {@link CollationKey} for an example using {@code CollationKey}s.
*
* @implNote Significant thread contention may occur during concurrent usage
* of the JDK Reference Implementation's {@link RuleBasedCollator}, which is the
* subtype returned by the default provider of the {@link #getInstance()} factory
* methods. As such, users should consider retrieving a separate instance for
* each thread when used in multithreaded environments.
*
* @see RuleBasedCollator
* @see CollationKey
* @see CollationElementIterator
* @see Locale
* @author Helena Shih, Laura Werner, Richard Gillam
* @since 1.1
*/
public abstract class Collator
implements java.util.Comparator<Object>, Cloneable
{
/**
* Collator strength value. When set, only PRIMARY differences are
* considered significant during comparison. The assignment of strengths
* to language features is locale dependent. A common example is for
* different base letters ("a" vs "b") to be considered a PRIMARY difference.
* @see java.text.Collator#setStrength
* @see java.text.Collator#getStrength
*/
public static final int PRIMARY = 0;
/**
* Collator strength value. When set, only SECONDARY and above differences are
* considered significant during comparison. The assignment of strengths
* to language features is locale dependent. A common example is for
* different accented forms of the same base letter ("a" vs "ä" (U+00E4)) to be
* considered a SECONDARY difference.
* @see java.text.Collator#setStrength
* @see java.text.Collator#getStrength
*/
public static final int SECONDARY = 1;
/**
* Collator strength value. When set, only TERTIARY and above differences are
* considered significant during comparison. The assignment of strengths
* to language features is locale dependent. A common example is for
* case differences ("a" vs "A") to be considered a TERTIARY difference.
* @see java.text.Collator#setStrength
* @see java.text.Collator#getStrength
*/
public static final int TERTIARY = 2;
/**
* Collator strength value. When set, all differences are
* considered significant during comparison. The assignment of strengths
* to language features is locale dependent. A common example is for control
* characters ("\u0001" vs "\u0002") to be considered equal at the
* PRIMARY, SECONDARY, and TERTIARY levels but different at the IDENTICAL
* level. Additionally, differences between pre-composed accents such as
* "\u00E4" (a-diaeresis) and combining accents such as "a\u0308"
* (a, combining-diaeresis) will be considered significant at the IDENTICAL
* level if decomposition is set to NO_DECOMPOSITION.
*/
public static final int IDENTICAL = 3;
/**
* Decomposition mode value. With NO_DECOMPOSITION
* set, accented characters will not be decomposed for collation. This
* setting provides the fastest collation but
* will only produce correct results for languages that do not use accents.
* @see java.text.Collator#getDecomposition
* @see java.text.Collator#setDecomposition
*/
public static final int NO_DECOMPOSITION = 0;
/**
* Decomposition mode value. With CANONICAL_DECOMPOSITION
* set, characters that are canonical variants according to Unicode
* standard will be decomposed for collation. This should be used to get
* correct collation of accented characters.
* <p>
* CANONICAL_DECOMPOSITION corresponds to Normalization Form D as
* described in
* <a href="http://www.unicode.org/reports/tr15/">Unicode
* Standard Annex #15: Unicode Normalization Forms</a>.
*
* @spec https://www.unicode.org/reports/tr15 Unicode Normalization Forms
* @see java.text.Collator#getDecomposition
* @see java.text.Collator#setDecomposition
*/
public static final int CANONICAL_DECOMPOSITION = 1;
/**
* Decomposition mode value. With FULL_DECOMPOSITION
* set, both Unicode canonical variants and Unicode compatibility variants
* will be decomposed for collation. This causes not only accented
* characters to be collated, but also characters that have special formats
* to be collated with their norminal form. For example, the half-width and
* full-width ASCII and Katakana characters are then collated together.
* FULL_DECOMPOSITION is the most complete and therefore the slowest
* decomposition mode.
* <p>
* FULL_DECOMPOSITION corresponds to Normalization Form KD as
* described in
* <a href="http://www.unicode.org/reports/tr15/">Unicode
* Standard Annex #15: Unicode Normalization Forms</a>.
*
* @spec https://www.unicode.org/reports/tr15 Unicode Normalization Forms
* @see java.text.Collator#getDecomposition
* @see java.text.Collator#setDecomposition
*/
public static final int FULL_DECOMPOSITION = 2;
/**
* Gets the Collator for the current default locale.
* The default locale is determined by {@link Locale#getDefault()}.
* @return the Collator for the default locale.(for example, en_US)
* @see java.util.Locale#getDefault
*/
public static synchronized Collator getInstance() {
return getInstance(Locale.getDefault());
}
/**
* Gets the Collator for the desired locale. If the desired locale
* has the "{@code ks}" and/or the "{@code kk}"
* <a href="https://www.unicode.org/reports/tr35/tr35-collation.html#Setting_Options">
* Unicode collation settings</a>, this method will call {@linkplain #setStrength(int)}
* and/or {@linkplain #setDecomposition(int)} on the created instance, if the specified
* Unicode collation settings are recognized based on the following mappings:
* <table class="striped">
* <caption style="display:none">Strength/Decomposition mappings</caption>
* <thead>
* <tr><th scope="col">BCP 47 values for strength (ks)</th>
* <th scope="col">Collator constants for strength</th></tr>
* </thead>
* <tbody>
* <tr><th scope="row" style="text-align:left">level1</th>
* <td>PRIMARY</td></tr>
* <tr><th scope="row" style="text-align:left">level2</th>
* <td>SECONDARY</td></tr>
* <tr><th scope="row" style="text-align:left">level3</th>
* <td>TERTIARY<sup>*</sup></td></tr>
* <tr><th scope="row" style="text-align:left">identic</th>
* <td>IDENTICAL</td></tr>
* </tbody>
* <thead>
* <tr><th scope="col">BCP 47 values for normalization (kk)</th>
* <th scope="col">Collator constants for decomposition</th></tr>
* </thead>
* <tbody>
* <tr><th scope="row" style="text-align:left">true</th>
* <td>CANONICAL_DECOMPOSITION</td></tr>
* <tr><th scope="row" style="text-align:left">false</th>
* <td>NO_DECOMPOSITION<sup>*</sup></td></tr>
* </tbody>
* </table>
* Asterisk (<sup>*</sup>) denotes the default value.
* If the specified setting value is not recognized, the strength and/or
* decomposition is not overridden, as if there were no BCP 47 collation
* options in the desired locale.
*
* @apiNote Implementations of {@code Collator} class may produce
* different instances based on the "{@code co}"
* <a href="https://www.unicode.org/reports/tr35/#UnicodeCollationIdentifier">
* Unicode collation identifier</a> in the {@code desiredLocale}.
* For example:
* {@snippet lang = java:
* Collator.getInstance(Locale.forLanguageTag("sv-u-co-trad"));
* }
* may return a {@code Collator} instance with the Swedish traditional sorting, which
* gives 'v' and 'w' the same sorting order, while the {@code Collator} instance
* for the Swedish locale without "co" identifier distinguishes 'v' and 'w'.
* @spec https://www.unicode.org/reports/tr35 Unicode Locale Data Markup Language
* (LDML)
* @param desiredLocale the desired locale.
* @return the Collator for the desired locale.
* @see java.util.Locale
* @see java.util.ResourceBundle
*/
public static Collator getInstance(Locale desiredLocale) {
SoftReference<Collator> ref = cache.get(desiredLocale);
Collator result = (ref != null) ? ref.get() : null;
if (result == null) {
LocaleProviderAdapter adapter;
adapter = LocaleProviderAdapter.getAdapter(CollatorProvider.class,
desiredLocale);
CollatorProvider provider = adapter.getCollatorProvider();
result = provider.getInstance(desiredLocale);
if (result == null) {
result = LocaleProviderAdapter.forJRE()
.getCollatorProvider().getInstance(desiredLocale);
}
// Override strength and decomposition with `desiredLocale`, if any
var strength = desiredLocale.getUnicodeLocaleType("ks");
if (strength != null) {
strength = strength.toLowerCase(Locale.ROOT);
switch (strength) {
case "level1" -> result.setStrength(PRIMARY);
case "level2" -> result.setStrength(SECONDARY);
case "level3" -> result.setStrength(TERTIARY);
case "identic" -> result.setStrength(IDENTICAL);
}
}
var norm = desiredLocale.getUnicodeLocaleType("kk");
if (norm != null) {
norm = norm.toLowerCase(Locale.ROOT);
switch (norm) {
case "true" -> result.setDecomposition(CANONICAL_DECOMPOSITION);
case "false" -> result.setDecomposition(NO_DECOMPOSITION);
}
}
while (true) {
if (ref != null) {
// Remove the empty SoftReference if any
cache.remove(desiredLocale, ref);
}
ref = cache.putIfAbsent(desiredLocale, new SoftReference<>(result));
if (ref == null) {
break;
}
Collator cachedColl = ref.get();
if (cachedColl != null) {
result = cachedColl;
break;
}
}
}
return (Collator) result.clone(); // make the world safe
}
/**
* Compares the source string to the target string according to the
* collation rules for this Collator. Returns an integer less than,
* equal to or greater than zero depending on whether the source String is
* less than, equal to or greater than the target string. See the Collator
* class description for an example of use.
* <p>
* For a one time comparison, this method has the best performance. If a
* given String will be involved in multiple comparisons, CollationKey.compareTo
* has the best performance. See the Collator class description for an example
* using CollationKeys.
* @param source the source string.
* @param target the target string.
* @return Returns an integer value. Value is less than zero if source is less than
* target, value is zero if source and target are equal, value is greater than zero
* if source is greater than target.
* @see java.text.CollationKey
* @see java.text.Collator#getCollationKey
*/
public abstract int compare(String source, String target);
/**
* Compares its two arguments for order. Returns a negative integer,
* zero, or a positive integer as the first argument is less than, equal
* to, or greater than the second.
* <p>
* This implementation merely returns
* {@code compare((String)o1, (String)o2) }.
*
* @return a negative integer, zero, or a positive integer as the
* first argument is less than, equal to, or greater than the
* second.
* @throws ClassCastException the arguments cannot be cast to Strings.
* @see java.util.Comparator
* @since 1.2
*/
@Override
public int compare(Object o1, Object o2) {
return compare((String)o1, (String)o2);
}
/**
* Transforms the String into a series of bits that can be compared bitwise
* to other CollationKeys. CollationKeys provide better performance than
* Collator.compare when Strings are involved in multiple comparisons.
* See the Collator class description for an example using CollationKeys.
* @param source the string to be transformed into a collation key.
* @return the CollationKey for the given String based on this Collator's collation
* rules. If the source String is null, a null CollationKey is returned.
* @see java.text.CollationKey
* @see java.text.Collator#compare
*/
public abstract CollationKey getCollationKey(String source);
/**
* Convenience method for comparing the equality of two strings based on
* this Collator's collation rules.
* @param source the source string to be compared with.
* @param target the target string to be compared with.
* @return true if the strings are equal according to the collation
* rules. false, otherwise.
* @see java.text.Collator#compare
*/
public boolean equals(String source, String target)
{
return (compare(source, target) == Collator.EQUAL);
}
/**
* Returns this Collator's strength property. The strength property determines
* the minimum level of difference considered significant during comparison.
* See the Collator class description for an example of use.
* @return this Collator's current strength property.
* @see java.text.Collator#setStrength
* @see java.text.Collator#PRIMARY
* @see java.text.Collator#SECONDARY
* @see java.text.Collator#TERTIARY
* @see java.text.Collator#IDENTICAL
*/
public synchronized int getStrength()
{
return strength;
}
/**
* Sets this Collator's strength property. The strength property determines
* the minimum level of difference considered significant during comparison.
* See the Collator class description for an example of use.
* @param newStrength the new strength value.
* @see java.text.Collator#getStrength
* @see java.text.Collator#PRIMARY
* @see java.text.Collator#SECONDARY
* @see java.text.Collator#TERTIARY
* @see java.text.Collator#IDENTICAL
* @throws IllegalArgumentException If the new strength value is not one of
* PRIMARY, SECONDARY, TERTIARY or IDENTICAL.
*/
public synchronized void setStrength(int newStrength) {
if ((newStrength != PRIMARY) &&
(newStrength != SECONDARY) &&
(newStrength != TERTIARY) &&
(newStrength != IDENTICAL)) {
throw new IllegalArgumentException("Incorrect comparison level.");
}
strength = newStrength;
}
/**
* Get the decomposition mode of this Collator. Decomposition mode
* determines how Unicode composed characters are handled. Adjusting
* decomposition mode allows the user to select between faster and more
* complete collation behavior.
* <p>The three values for decomposition mode are:
* <UL>
* <LI>NO_DECOMPOSITION,
* <LI>CANONICAL_DECOMPOSITION
* <LI>FULL_DECOMPOSITION.
* </UL>
* See the documentation for these three constants for a description
* of their meaning.
* @return the decomposition mode
* @see java.text.Collator#setDecomposition
* @see java.text.Collator#NO_DECOMPOSITION
* @see java.text.Collator#CANONICAL_DECOMPOSITION
* @see java.text.Collator#FULL_DECOMPOSITION
*/
public synchronized int getDecomposition()
{
return decmp;
}
/**
* Set the decomposition mode of this Collator. See getDecomposition
* for a description of decomposition mode.
* @param decompositionMode the new decomposition mode.
* @see java.text.Collator#getDecomposition
* @see java.text.Collator#NO_DECOMPOSITION
* @see java.text.Collator#CANONICAL_DECOMPOSITION
* @see java.text.Collator#FULL_DECOMPOSITION
* @throws IllegalArgumentException If the given value is not a valid decomposition
* mode.
*/
public synchronized void setDecomposition(int decompositionMode) {
if ((decompositionMode != NO_DECOMPOSITION) &&
(decompositionMode != CANONICAL_DECOMPOSITION) &&
(decompositionMode != FULL_DECOMPOSITION)) {
throw new IllegalArgumentException("Wrong decomposition mode.");
}
decmp = decompositionMode;
}
/**
* Returns an array of all locales for which the
* {@code getInstance} methods of this class can return
* localized instances.
* The returned array represents the union of locales supported
* by the Java runtime and by installed
* {@link java.text.spi.CollatorProvider CollatorProvider} implementations.
* At a minimum, the returned array must contain a {@code Locale} instance equal to
* {@link Locale#ROOT Locale.ROOT} and a {@code Locale} instance equal to
* {@link Locale#US Locale.US}.
*
* @return An array of locales for which localized
* {@code Collator} instances are available.
*/
public static synchronized Locale[] getAvailableLocales() {
LocaleServiceProviderPool pool =
LocaleServiceProviderPool.getPool(CollatorProvider.class);
return pool.getAvailableLocales();
}
/**
* Overrides Cloneable
*/
@Override
public Object clone()
{
try {
return (Collator)super.clone();
} catch (CloneNotSupportedException e) {
throw new InternalError(e);
}
}
/**
* Compares the equality of two Collators.
* @param that the Collator to be compared with this.
* @return true if this Collator is the same as that Collator;
* false otherwise.
*/
@Override
public boolean equals(Object that)
{
if (this == that) {
return true;
}
if (that == null || getClass() != that.getClass()) {
return false;
}
Collator other = (Collator) that;
return ((strength == other.strength) &&
(decmp == other.decmp));
}
/**
* Generates the hash code for this Collator.
*/
@Override
public abstract int hashCode();
/**
* Default constructor. This constructor is
* protected so subclasses can get access to it. Users typically create
* a Collator sub-class by calling the factory method getInstance.
* @see java.text.Collator#getInstance
*/
protected Collator()
{
strength = TERTIARY;
decmp = CANONICAL_DECOMPOSITION;
}
private int strength = 0;
private int decmp = 0;
private static final ConcurrentMap<Locale, SoftReference<Collator>> cache
= new ConcurrentHashMap<>();
//
// FIXME: These three constants should be removed.
//
/**
* LESS is returned if source string is compared to be less than target
* string in the compare() method.
* @see java.text.Collator#compare
*/
static final int LESS = -1;
/**
* EQUAL is returned if source string is compared to be equal to target
* string in the compare() method.
* @see java.text.Collator#compare
*/
static final int EQUAL = 0;
/**
* GREATER is returned if source string is compared to be greater than
* target string in the compare() method.
* @see java.text.Collator#compare
*/
static final int GREATER = 1;
}