Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1294 insertions, 0 deletions

diff --git a/intl/icu/source/i18n/unicode/coll.h b/intl/icu/source/i18n/unicode/coll.h
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+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+/*
+******************************************************************************
+*   Copyright (C) 1996-2016, International Business Machines
+*   Corporation and others.  All Rights Reserved.
+******************************************************************************
+*/
+
+/**
+ * \file
+ * \brief C++ API: Collation Service.
+ */
+
+/**
+* File coll.h
+*
+* Created by: Helena Shih
+*
+* Modification History:
+*
+*  Date        Name        Description
+* 02/5/97      aliu        Modified createDefault to load collation data from
+*                          binary files when possible.  Added related methods
+*                          createCollationFromFile, chopLocale, createPathName.
+* 02/11/97     aliu        Added members addToCache, findInCache, and fgCache.
+* 02/12/97     aliu        Modified to create objects from RuleBasedCollator cache.
+*                          Moved cache out of Collation class.
+* 02/13/97     aliu        Moved several methods out of this class and into
+*                          RuleBasedCollator, with modifications.  Modified
+*                          createDefault() to call new RuleBasedCollator(Locale&)
+*                          constructor.  General clean up and documentation.
+* 02/20/97     helena      Added clone, operator==, operator!=, operator=, copy
+*                          constructor and getDynamicClassID.
+* 03/25/97     helena      Updated with platform independent data types.
+* 05/06/97     helena      Added memory allocation error detection.
+* 06/20/97     helena      Java class name change.
+* 09/03/97     helena      Added createCollationKeyValues().
+* 02/10/98     damiba      Added compare() with length as parameter.
+* 04/23/99     stephen     Removed EDecompositionMode, merged with
+*                          Normalizer::EMode.
+* 11/02/99     helena      Collator performance enhancements.  Eliminates the
+*                          UnicodeString construction and special case for NO_OP.
+* 11/23/99     srl         More performance enhancements. Inlining of
+*                          critical accessors.
+* 05/15/00     helena      Added version information API.
+* 01/29/01     synwee      Modified into a C++ wrapper which calls C apis
+*                          (ucol.h).
+* 2012-2014    markus      Rewritten in C++ again.
+*/
+
+#ifndef COLL_H
+#define COLL_H
+
+#include "unicode/utypes.h"
+
+#if U_SHOW_CPLUSPLUS_API
+
+#if !UCONFIG_NO_COLLATION
+
+#include "unicode/uobject.h"
+#include "unicode/ucol.h"
+#include "unicode/unorm.h"
+#include "unicode/locid.h"
+#include "unicode/uniset.h"
+#include "unicode/umisc.h"
+#include "unicode/uiter.h"
+#include "unicode/stringpiece.h"
+
+U_NAMESPACE_BEGIN
+
+class StringEnumeration;
+
+#if !UCONFIG_NO_SERVICE
+/**
+ * @stable ICU 2.6
+ */
+class CollatorFactory;
+#endif
+
+/**
+* @stable ICU 2.0
+*/
+class CollationKey;
+
+/**
+* The <code>Collator</code> class performs locale-sensitive string
+* comparison.<br>
+* You use this class to build searching and sorting routines for natural
+* language text.
+* <p>
+* <code>Collator</code> is an abstract base class. Subclasses implement
+* specific collation strategies. One subclass,
+* <code>RuleBasedCollator</code>, is currently provided 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>createInstance</code>, to obtain the appropriate
+* <code>Collator</code> object for a given locale. You will only need to
+* look at the subclasses of <code>Collator</code> 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</code> for the default locale.
+* \htmlonly<blockquote>\endhtmlonly
+* <pre>
+* \code
+* // Compare two strings in the default locale
+* UErrorCode success = U_ZERO_ERROR;
+* Collator* myCollator = Collator::createInstance(success);
+* if (myCollator->compare("abc", "ABC") < 0)
+*   cout << "abc is less than ABC" << endl;
+* else
+*   cout << "abc is greater than or equal to ABC" << endl;
+* \endcode
+* </pre>
+* \htmlonly</blockquote>\endhtmlonly
+* <p>
+* You can set a <code>Collator</code>'s <em>strength</em> attribute to
+* determine the level of difference considered significant in comparisons.
+* Five strengths are provided: <code>PRIMARY</code>, <code>SECONDARY</code>,
+* <code>TERTIARY</code>, <code>QUATERNARY</code> and <code>IDENTICAL</code>.
+* 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 "\u00EA" 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.
+* \htmlonly<blockquote>\endhtmlonly
+* <pre>
+* \code
+* //Get the Collator for US English and set its strength to PRIMARY
+* UErrorCode success = U_ZERO_ERROR;
+* Collator* usCollator = Collator::createInstance(Locale::getUS(), success);
+* usCollator->setStrength(Collator::PRIMARY);
+* if (usCollator->compare("abc", "ABC") == 0)
+*     cout << "'abc' and 'ABC' strings are equivalent with strength PRIMARY" << endl;
+* \endcode
+* </pre>
+* \htmlonly</blockquote>\endhtmlonly
+*
+* The <code>getSortKey</code> methods
+* convert a string to a series of bytes that can be compared bitwise against
+* other sort keys using <code>strcmp()</code>. Sort keys are written as
+* zero-terminated byte strings.
+*
+* Another set of APIs returns a <code>CollationKey</code> object that wraps
+* the sort key bytes instead of returning the bytes themselves.
+* </p>
+* <p>
+* <strong>Note:</strong> <code>Collator</code>s with different Locale,
+* and CollationStrength settings will return different sort
+* orders for the same set of strings. Locales have specific collation rules,
+* and the way in which secondary and tertiary differences are taken into
+* account, for example, will result in a different sorting order for same
+* strings.
+* </p>
+* @see         RuleBasedCollator
+* @see         CollationKey
+* @see         CollationElementIterator
+* @see         Locale
+* @see         Normalizer2
+* @version     2.0 11/15/01
+*/
+
+class U_I18N_API Collator : public UObject {
+public:
+
+    // Collator public enums -----------------------------------------------
+
+    /**
+     * Base letter represents a primary difference. Set comparison level to
+     * PRIMARY to ignore secondary and tertiary differences.<br>
+     * Use this to set the strength of a Collator object.<br>
+     * Example of primary difference, "abc" &lt; "abd"
+     *
+     * Diacritical differences on the same base letter represent a secondary
+     * difference. Set comparison level to SECONDARY to ignore tertiary
+     * differences. Use this to set the strength of a Collator object.<br>
+     * Example of secondary difference, "&auml;" >> "a".
+     *
+     * Uppercase and lowercase versions of the same character represents a
+     * tertiary difference.  Set comparison level to TERTIARY to include all
+     * comparison differences. Use this to set the strength of a Collator
+     * object.<br>
+     * Example of tertiary difference, "abc" &lt;&lt;&lt; "ABC".
+     *
+     * Two characters are considered "identical" when they have the same unicode
+     * spellings.<br>
+     * For example, "&auml;" == "&auml;".
+     *
+     * UCollationStrength is also used to determine the strength of sort keys
+     * generated from Collator objects.
+     * @stable ICU 2.0
+     */
+    enum ECollationStrength
+    {
+        PRIMARY    = UCOL_PRIMARY,  // 0
+        SECONDARY  = UCOL_SECONDARY,  // 1
+        TERTIARY   = UCOL_TERTIARY,  // 2
+        QUATERNARY = UCOL_QUATERNARY,  // 3
+        IDENTICAL  = UCOL_IDENTICAL  // 15
+    };
+
+
+    // Cannot use #ifndef U_HIDE_DEPRECATED_API for the following, it is
+    // used by virtual methods that cannot have that conditional.
+#ifndef U_FORCE_HIDE_DEPRECATED_API
+    /**
+     * LESS is returned if source string is compared to be less than target
+     * string in the compare() method.
+     * EQUAL is returned if source string is compared to be equal to target
+     * string in the compare() method.
+     * GREATER is returned if source string is compared to be greater than
+     * target string in the compare() method.
+     * @see Collator#compare
+     * @deprecated ICU 2.6. Use C enum UCollationResult defined in ucol.h
+     */
+    enum EComparisonResult
+    {
+        LESS = UCOL_LESS,  // -1
+        EQUAL = UCOL_EQUAL,  // 0
+        GREATER = UCOL_GREATER  // 1
+    };
+#endif  // U_FORCE_HIDE_DEPRECATED_API
+
+    // Collator public destructor -----------------------------------------
+
+    /**
+     * Destructor
+     * @stable ICU 2.0
+     */
+    virtual ~Collator();
+
+    // Collator public methods --------------------------------------------
+
+    /**
+     * Returns true if "other" is the same as "this".
+     *
+     * The base class implementation returns true if "other" has the same type/class as "this":
+     * `typeid(*this) == typeid(other)`.
+     *
+     * Subclass implementations should do something like the following:
+     *
+     *     if (this == &other) { return true; }
+     *     if (!Collator::operator==(other)) { return false; }  // not the same class
+     *
+     *     const MyCollator &o = (const MyCollator&)other;
+     *     (compare this vs. o's subclass fields)
+     *
+     * @param other Collator object to be compared
+     * @return true if other is the same as this.
+     * @stable ICU 2.0
+     */
+    virtual bool operator==(const Collator& other) const;
+
+    /**
+     * Returns true if "other" is not the same as "this".
+     * Calls ! operator==(const Collator&) const which works for all subclasses.
+     * @param other Collator object to be compared
+     * @return true if other is not the same as this.
+     * @stable ICU 2.0
+     */
+    virtual bool operator!=(const Collator& other) const;
+
+    /**
+     * Makes a copy of this object.
+     * @return a copy of this object, owned by the caller
+     * @stable ICU 2.0
+     */
+    virtual Collator* clone() const = 0;
+
+    /**
+     * Creates the Collator object for the current default locale.
+     * The default locale is determined by Locale::getDefault.
+     * The UErrorCode& err parameter is used to return status information to the user.
+     * To check whether the construction succeeded or not, you should check the
+     * value of U_SUCCESS(err).  If you wish more detailed information, you can
+     * check for informational error results which still indicate success.
+     * U_USING_FALLBACK_ERROR indicates that a fall back locale was used. For
+     * example, 'de_CH' was requested, but nothing was found there, so 'de' was
+     * used. U_USING_DEFAULT_ERROR indicates that the default locale data was
+     * used; neither the requested locale nor any of its fall back locales
+     * could be found.
+     * The caller owns the returned object and is responsible for deleting it.
+     *
+     * @param err    the error code status.
+     * @return       the collation object of the default locale.(for example, en_US)
+     * @see Locale#getDefault
+     * @stable ICU 2.0
+     */
+    static Collator* U_EXPORT2 createInstance(UErrorCode&  err);
+
+    /**
+     * Gets the collation object for the desired locale. The
+     * resource of the desired locale will be loaded.
+     *
+     * Locale::getRoot() is the base collation table and all other languages are
+     * built on top of it with additional language-specific modifications.
+     *
+     * For some languages, multiple collation types are available;
+     * for example, "de@collation=phonebook".
+     * Starting with ICU 54, collation attributes can be specified via locale keywords as well,
+     * in the old locale extension syntax ("el@colCaseFirst=upper")
+     * or in language tag syntax ("el-u-kf-upper").
+     * See <a href="https://unicode-org.github.io/icu/userguide/collation/api">User Guide: Collation API</a>.
+     *
+     * The UErrorCode& err parameter is used to return status information to the user.
+     * To check whether the construction succeeded or not, you should check
+     * the value of U_SUCCESS(err).  If you wish more detailed information, you
+     * can check for informational error results which still indicate success.
+     * U_USING_FALLBACK_ERROR indicates that a fall back locale was used.  For
+     * example, 'de_CH' was requested, but nothing was found there, so 'de' was
+     * used.  U_USING_DEFAULT_ERROR indicates that the default locale data was
+     * used; neither the requested locale nor any of its fall back locales
+     * could be found.
+     *
+     * The caller owns the returned object and is responsible for deleting it.
+     * @param loc    The locale ID for which to open a collator.
+     * @param err    the error code status.
+     * @return       the created table-based collation object based on the desired
+     *               locale.
+     * @see Locale
+     * @see ResourceLoader
+     * @stable ICU 2.2
+     */
+    static Collator* U_EXPORT2 createInstance(const Locale& loc, UErrorCode& err);
+
+#ifndef U_FORCE_HIDE_DEPRECATED_API
+    /**
+     * The comparison function compares the character data stored in two
+     * different strings. Returns information about whether a string is less
+     * than, greater than or equal to another string.
+     * @param source the source string to be compared with.
+     * @param target the string that is to be compared with the source string.
+     * @return Returns a byte value. GREATER if source is greater
+     * than target; EQUAL if source is equal to target; LESS if source is less
+     * than target
+     * @deprecated ICU 2.6 use the overload with UErrorCode &
+     */
+    virtual EComparisonResult compare(const UnicodeString& source,
+                                      const UnicodeString& target) const;
+#endif  // U_FORCE_HIDE_DEPRECATED_API
+
+    /**
+     * The comparison function compares the character data stored in two
+     * different strings. Returns information about whether a string is less
+     * than, greater than or equal to another string.
+     * @param source the source string to be compared with.
+     * @param target the string that is to be compared with the source string.
+     * @param status possible error code
+     * @return Returns an enum value. UCOL_GREATER if source is greater
+     * than target; UCOL_EQUAL if source is equal to target; UCOL_LESS if source is less
+     * than target
+     * @stable ICU 2.6
+     */
+    virtual UCollationResult compare(const UnicodeString& source,
+                                      const UnicodeString& target,
+                                      UErrorCode &status) const = 0;
+
+#ifndef U_FORCE_HIDE_DEPRECATED_API
+    /**
+     * Does the same thing as compare but limits the comparison to a specified
+     * length
+     * @param source the source string to be compared with.
+     * @param target the string that is to be compared with the source string.
+     * @param length the length the comparison is limited to
+     * @return Returns a byte value. GREATER if source (up to the specified
+     *         length) is greater than target; EQUAL if source (up to specified
+     *         length) is equal to target; LESS if source (up to the specified
+     *         length) is less  than target.
+     * @deprecated ICU 2.6 use the overload with UErrorCode &
+     */
+    virtual EComparisonResult compare(const UnicodeString& source,
+                                      const UnicodeString& target,
+                                      int32_t length) const;
+#endif  // U_FORCE_HIDE_DEPRECATED_API
+
+    /**
+     * Does the same thing as compare but limits the comparison to a specified
+     * length
+     * @param source the source string to be compared with.
+     * @param target the string that is to be compared with the source string.
+     * @param length the length the comparison is limited to
+     * @param status possible error code
+     * @return Returns an enum value. UCOL_GREATER if source (up to the specified
+     *         length) is greater than target; UCOL_EQUAL if source (up to specified
+     *         length) is equal to target; UCOL_LESS if source (up to the specified
+     *         length) is less  than target.
+     * @stable ICU 2.6
+     */
+    virtual UCollationResult compare(const UnicodeString& source,
+                                      const UnicodeString& target,
+                                      int32_t length,
+                                      UErrorCode &status) const = 0;
+
+#ifndef U_FORCE_HIDE_DEPRECATED_API
+    /**
+     * The comparison function compares the character data stored in two
+     * different string arrays. Returns information about whether a string array
+     * is less than, greater than or equal to another string array.
+     * <p>Example of use:
+     * <pre>
+     * .       char16_t ABC[] = {0x41, 0x42, 0x43, 0};  // = "ABC"
+     * .       char16_t abc[] = {0x61, 0x62, 0x63, 0};  // = "abc"
+     * .       UErrorCode status = U_ZERO_ERROR;
+     * .       Collator *myCollation =
+     * .                         Collator::createInstance(Locale::getUS(), status);
+     * .       if (U_FAILURE(status)) return;
+     * .       myCollation->setStrength(Collator::PRIMARY);
+     * .       // result would be Collator::EQUAL ("abc" == "ABC")
+     * .       // (no primary difference between "abc" and "ABC")
+     * .       Collator::EComparisonResult result =
+     * .                             myCollation->compare(abc, 3, ABC, 3);
+     * .       myCollation->setStrength(Collator::TERTIARY);
+     * .       // result would be Collator::LESS ("abc" &lt;&lt;&lt; "ABC")
+     * .       // (with tertiary difference between "abc" and "ABC")
+     * .       result = myCollation->compare(abc, 3, ABC, 3);
+     * </pre>
+     * @param source the source string array to be compared with.
+     * @param sourceLength the length of the source string array.  If this value
+     *        is equal to -1, the string array is null-terminated.
+     * @param target the string that is to be compared with the source string.
+     * @param targetLength the length of the target string array.  If this value
+     *        is equal to -1, the string array is null-terminated.
+     * @return Returns a byte value. GREATER if source is greater than target;
+     *         EQUAL if source is equal to target; LESS if source is less than
+     *         target
+     * @deprecated ICU 2.6 use the overload with UErrorCode &
+     */
+    virtual EComparisonResult compare(const char16_t* source, int32_t sourceLength,
+                                      const char16_t* target, int32_t targetLength)
+                                      const;
+#endif  // U_FORCE_HIDE_DEPRECATED_API
+
+    /**
+     * The comparison function compares the character data stored in two
+     * different string arrays. Returns information about whether a string array
+     * is less than, greater than or equal to another string array.
+     * @param source the source string array to be compared with.
+     * @param sourceLength the length of the source string array.  If this value
+     *        is equal to -1, the string array is null-terminated.
+     * @param target the string that is to be compared with the source string.
+     * @param targetLength the length of the target string array.  If this value
+     *        is equal to -1, the string array is null-terminated.
+     * @param status possible error code
+     * @return Returns an enum value. UCOL_GREATER if source is greater
+     * than target; UCOL_EQUAL if source is equal to target; UCOL_LESS if source is less
+     * than target
+     * @stable ICU 2.6
+     */
+    virtual UCollationResult compare(const char16_t* source, int32_t sourceLength,
+                                      const char16_t* target, int32_t targetLength,
+                                      UErrorCode &status) const = 0;
+
+    /**
+     * Compares two strings using the Collator.
+     * Returns whether the first one compares less than/equal to/greater than
+     * the second one.
+     * This version takes UCharIterator input.
+     * @param sIter the first ("source") string iterator
+     * @param tIter the second ("target") string iterator
+     * @param status ICU status
+     * @return UCOL_LESS, UCOL_EQUAL or UCOL_GREATER
+     * @stable ICU 4.2
+     */
+    virtual UCollationResult compare(UCharIterator &sIter,
+                                     UCharIterator &tIter,
+                                     UErrorCode &status) const;
+
+    /**
+     * Compares two UTF-8 strings using the Collator.
+     * Returns whether the first one compares less than/equal to/greater than
+     * the second one.
+     * This version takes UTF-8 input.
+     * Note that a StringPiece can be implicitly constructed
+     * from a std::string or a NUL-terminated const char * string.
+     * @param source the first UTF-8 string
+     * @param target the second UTF-8 string
+     * @param status ICU status
+     * @return UCOL_LESS, UCOL_EQUAL or UCOL_GREATER
+     * @stable ICU 4.2
+     */
+    virtual UCollationResult compareUTF8(const StringPiece &source,
+                                         const StringPiece &target,
+                                         UErrorCode &status) const;
+
+    /**
+     * Transforms the string into a series of characters that can be compared
+     * with CollationKey::compareTo. It is not possible to restore the original
+     * string from the chars in the sort key.
+     * <p>Use CollationKey::equals or CollationKey::compare to compare the
+     * generated sort keys.
+     * If the source string is null, a null collation key will be returned.
+     *
+     * Note that sort keys are often less efficient than simply doing comparison.
+     * For more details, see the ICU User Guide.
+     *
+     * @param source the source string to be transformed into a sort key.
+     * @param key the collation key to be filled in
+     * @param status the error code status.
+     * @return the collation key of the string based on the collation rules.
+     * @see CollationKey#compare
+     * @stable ICU 2.0
+     */
+    virtual CollationKey& getCollationKey(const UnicodeString&  source,
+                                          CollationKey& key,
+                                          UErrorCode& status) const = 0;
+
+    /**
+     * Transforms the string into a series of characters that can be compared
+     * with CollationKey::compareTo. It is not possible to restore the original
+     * string from the chars in the sort key.
+     * <p>Use CollationKey::equals or CollationKey::compare to compare the
+     * generated sort keys.
+     * <p>If the source string is null, a null collation key will be returned.
+     *
+     * Note that sort keys are often less efficient than simply doing comparison.
+     * For more details, see the ICU User Guide.
+     *
+     * @param source the source string to be transformed into a sort key.
+     * @param sourceLength length of the collation key
+     * @param key the collation key to be filled in
+     * @param status the error code status.
+     * @return the collation key of the string based on the collation rules.
+     * @see CollationKey#compare
+     * @stable ICU 2.0
+     */
+    virtual CollationKey& getCollationKey(const char16_t*source,
+                                          int32_t sourceLength,
+                                          CollationKey& key,
+                                          UErrorCode& status) const = 0;
+    /**
+     * Generates the hash code for the collation object
+     * @stable ICU 2.0
+     */
+    virtual int32_t hashCode(void) const = 0;
+
+#ifndef U_FORCE_HIDE_DEPRECATED_API
+    /**
+     * Gets the locale of the Collator
+     *
+     * @param type can be either requested, valid or actual locale. For more
+     *             information see the definition of ULocDataLocaleType in
+     *             uloc.h
+     * @param status the error code status.
+     * @return locale where the collation data lives. If the collator
+     *         was instantiated from rules, locale is empty.
+     * @deprecated ICU 2.8 This API is under consideration for revision
+     * in ICU 3.0.
+     */
+    virtual Locale getLocale(ULocDataLocaleType type, UErrorCode& status) const = 0;
+#endif  // U_FORCE_HIDE_DEPRECATED_API
+
+    /**
+     * Convenience method for comparing two strings based on the collation rules.
+     * @param source the source string to be compared with.
+     * @param target the target string to be compared with.
+     * @return true if the first string is greater than the second one,
+     *         according to the collation rules. false, otherwise.
+     * @see Collator#compare
+     * @stable ICU 2.0
+     */
+    UBool greater(const UnicodeString& source, const UnicodeString& target)
+                  const;
+
+    /**
+     * Convenience method for comparing two strings based on the collation rules.
+     * @param source the source string to be compared with.
+     * @param target the target string to be compared with.
+     * @return true if the first string is greater than or equal to the second
+     *         one, according to the collation rules. false, otherwise.
+     * @see Collator#compare
+     * @stable ICU 2.0
+     */
+    UBool greaterOrEqual(const UnicodeString& source,
+                         const UnicodeString& target) const;
+
+    /**
+     * Convenience method for comparing two strings based on the 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 Collator#compare
+     * @stable ICU 2.0
+     */
+    UBool equals(const UnicodeString& source, const UnicodeString& target) const;
+
+#ifndef U_FORCE_HIDE_DEPRECATED_API
+    /**
+     * Determines the minimum strength that will be used in comparison or
+     * transformation.
+     * <p>E.g. with strength == SECONDARY, the tertiary difference is ignored
+     * <p>E.g. with strength == PRIMARY, the secondary and tertiary difference
+     * are ignored.
+     * @return the current comparison level.
+     * @see Collator#setStrength
+     * @deprecated ICU 2.6 Use getAttribute(UCOL_STRENGTH...) instead
+     */
+    virtual ECollationStrength getStrength(void) const;
+
+    /**
+     * Sets the minimum strength to be used in comparison or transformation.
+     * <p>Example of use:
+     * <pre>
+     *  \code
+     *  UErrorCode status = U_ZERO_ERROR;
+     *  Collator*myCollation = Collator::createInstance(Locale::getUS(), status);
+     *  if (U_FAILURE(status)) return;
+     *  myCollation->setStrength(Collator::PRIMARY);
+     *  // result will be "abc" == "ABC"
+     *  // tertiary differences will be ignored
+     *  Collator::ComparisonResult result = myCollation->compare("abc", "ABC");
+     * \endcode
+     * </pre>
+     * @see Collator#getStrength
+     * @param newStrength the new comparison level.
+     * @deprecated ICU 2.6 Use setAttribute(UCOL_STRENGTH...) instead
+     */
+    virtual void setStrength(ECollationStrength newStrength);
+#endif  // U_FORCE_HIDE_DEPRECATED_API
+
+    /**
+     * Retrieves the reordering codes for this collator.
+     * @param dest The array to fill with the script ordering.
+     * @param destCapacity The length of dest. If it is 0, then dest may be nullptr and the function
+     *  will only return the length of the result without writing any codes (pre-flighting).
+     * @param status A reference to an error code value, which must not indicate
+     * a failure before the function call.
+     * @return The length of the script ordering array.
+     * @see ucol_setReorderCodes
+     * @see Collator#getEquivalentReorderCodes
+     * @see Collator#setReorderCodes
+     * @see UScriptCode
+     * @see UColReorderCode
+     * @stable ICU 4.8
+     */
+     virtual int32_t getReorderCodes(int32_t *dest,
+                                     int32_t destCapacity,
+                                     UErrorCode& status) const;
+
+    /**
+     * Sets the ordering of scripts for this collator.
+     *
+     * <p>The reordering codes are a combination of script codes and reorder codes.
+     * @param reorderCodes An array of script codes in the new order. This can be nullptr if the
+     * length is also set to 0. An empty array will clear any reordering codes on the collator.
+     * @param reorderCodesLength The length of reorderCodes.
+     * @param status error code
+     * @see ucol_setReorderCodes
+     * @see Collator#getReorderCodes
+     * @see Collator#getEquivalentReorderCodes
+     * @see UScriptCode
+     * @see UColReorderCode
+     * @stable ICU 4.8
+     */
+     virtual void setReorderCodes(const int32_t* reorderCodes,
+                                  int32_t reorderCodesLength,
+                                  UErrorCode& status) ;
+
+    /**
+     * Retrieves the reorder codes that are grouped with the given reorder code. Some reorder
+     * codes will be grouped and must reorder together.
+     * Beginning with ICU 55, scripts only reorder together if they are primary-equal,
+     * for example Hiragana and Katakana.
+     *
+     * @param reorderCode The reorder code to determine equivalence for.
+     * @param dest The array to fill with the script equivalence reordering codes.
+     * @param destCapacity The length of dest. If it is 0, then dest may be nullptr and the
+     * function will only return the length of the result without writing any codes (pre-flighting).
+     * @param status A reference to an error code value, which must not indicate
+     * a failure before the function call.
+     * @return The length of the of the reordering code equivalence array.
+     * @see ucol_setReorderCodes
+     * @see Collator#getReorderCodes
+     * @see Collator#setReorderCodes
+     * @see UScriptCode
+     * @see UColReorderCode
+     * @stable ICU 4.8
+     */
+    static int32_t U_EXPORT2 getEquivalentReorderCodes(int32_t reorderCode,
+                                int32_t* dest,
+                                int32_t destCapacity,
+                                UErrorCode& status);
+
+    /**
+     * Get name of the object for the desired Locale, in the desired language
+     * @param objectLocale must be from getAvailableLocales
+     * @param displayLocale specifies the desired locale for output
+     * @param name the fill-in parameter of the return value
+     * @return display-able name of the object for the object locale in the
+     *         desired language
+     * @stable ICU 2.0
+     */
+    static UnicodeString& U_EXPORT2 getDisplayName(const Locale& objectLocale,
+                                         const Locale& displayLocale,
+                                         UnicodeString& name);
+
+    /**
+    * Get name of the object for the desired Locale, in the language of the
+    * default locale.
+    * @param objectLocale must be from getAvailableLocales
+    * @param name the fill-in parameter of the return value
+    * @return name of the object for the desired locale in the default language
+    * @stable ICU 2.0
+    */
+    static UnicodeString& U_EXPORT2 getDisplayName(const Locale& objectLocale,
+                                         UnicodeString& name);
+
+    /**
+     * Get the set of Locales for which Collations are installed.
+     *
+     * <p>Note this does not include locales supported by registered collators.
+     * If collators might have been registered, use the overload of getAvailableLocales
+     * that returns a StringEnumeration.</p>
+     *
+     * @param count the output parameter of number of elements in the locale list
+     * @return the list of available locales for which collations are installed
+     * @stable ICU 2.0
+     */
+    static const Locale* U_EXPORT2 getAvailableLocales(int32_t& count);
+
+    /**
+     * Return a StringEnumeration over the locales available at the time of the call,
+     * including registered locales.  If a severe error occurs (such as out of memory
+     * condition) this will return null. If there is no locale data, an empty enumeration
+     * will be returned.
+     * @return a StringEnumeration over the locales available at the time of the call
+     * @stable ICU 2.6
+     */
+    static StringEnumeration* U_EXPORT2 getAvailableLocales(void);
+
+    /**
+     * Create a string enumerator of all possible keywords that are relevant to
+     * collation. At this point, the only recognized keyword for this
+     * service is "collation".
+     * @param status input-output error code
+     * @return a string enumeration over locale strings. The caller is
+     * responsible for closing the result.
+     * @stable ICU 3.0
+     */
+    static StringEnumeration* U_EXPORT2 getKeywords(UErrorCode& status);
+
+    /**
+     * Given a keyword, create a string enumeration of all values
+     * for that keyword that are currently in use.
+     * @param keyword a particular keyword as enumerated by
+     * ucol_getKeywords. If any other keyword is passed in, status is set
+     * to U_ILLEGAL_ARGUMENT_ERROR.
+     * @param status input-output error code
+     * @return a string enumeration over collation keyword values, or nullptr
+     * upon error. The caller is responsible for deleting the result.
+     * @stable ICU 3.0
+     */
+    static StringEnumeration* U_EXPORT2 getKeywordValues(const char *keyword, UErrorCode& status);
+
+    /**
+     * Given a key and a locale, returns an array of string values in a preferred
+     * order that would make a difference. These are all and only those values where
+     * the open (creation) of the service with the locale formed from the input locale
+     * plus input keyword and that value has different behavior than creation with the
+     * input locale alone.
+     * @param keyword        one of the keys supported by this service.  For now, only
+     *                      "collation" is supported.
+     * @param locale        the locale
+     * @param commonlyUsed  if set to true it will return only commonly used values
+     *                      with the given locale in preferred order.  Otherwise,
+     *                      it will return all the available values for the locale.
+     * @param status ICU status
+     * @return a string enumeration over keyword values for the given key and the locale.
+     * @stable ICU 4.2
+     */
+    static StringEnumeration* U_EXPORT2 getKeywordValuesForLocale(const char* keyword, const Locale& locale,
+                                                                    UBool commonlyUsed, UErrorCode& status);
+
+    /**
+     * Return the functionally equivalent locale for the given
+     * requested locale, with respect to given keyword, for the
+     * collation service.  If two locales return the same result, then
+     * collators instantiated for these locales will behave
+     * equivalently.  The converse is not always true; two collators
+     * may in fact be equivalent, but return different results, due to
+     * internal details.  The return result has no other meaning than
+     * that stated above, and implies nothing as to the relationship
+     * between the two locales.  This is intended for use by
+     * applications who wish to cache collators, or otherwise reuse
+     * collators when possible.  The functional equivalent may change
+     * over time.  For more information, please see the <a
+     * href="https://unicode-org.github.io/icu/userguide/locale#locales-and-services">
+     * Locales and Services</a> section of the ICU User Guide.
+     * @param keyword a particular keyword as enumerated by
+     * ucol_getKeywords.
+     * @param locale the requested locale
+     * @param isAvailable reference to a fillin parameter that
+     * indicates whether the requested locale was 'available' to the
+     * collation service. A locale is defined as 'available' if it
+     * physically exists within the collation locale data.
+     * @param status reference to input-output error code
+     * @return the functionally equivalent collation locale, or the root
+     * locale upon error.
+     * @stable ICU 3.0
+     */
+    static Locale U_EXPORT2 getFunctionalEquivalent(const char* keyword, const Locale& locale,
+                                          UBool& isAvailable, UErrorCode& status);
+
+#if !UCONFIG_NO_SERVICE
+    /**
+     * Register a new Collator.  The collator will be adopted.
+     * Because ICU may choose to cache collators internally, this must be
+     * called at application startup, prior to any calls to
+     * Collator::createInstance to avoid undefined behavior.
+     * @param toAdopt the Collator instance to be adopted
+     * @param locale the locale with which the collator will be associated
+     * @param status the in/out status code, no special meanings are assigned
+     * @return a registry key that can be used to unregister this collator
+     * @stable ICU 2.6
+     */
+    static URegistryKey U_EXPORT2 registerInstance(Collator* toAdopt, const Locale& locale, UErrorCode& status);
+
+    /**
+     * Register a new CollatorFactory.  The factory will be adopted.
+     * Because ICU may choose to cache collators internally, this must be
+     * called at application startup, prior to any calls to
+     * Collator::createInstance to avoid undefined behavior.
+     * @param toAdopt the CollatorFactory instance to be adopted
+     * @param status the in/out status code, no special meanings are assigned
+     * @return a registry key that can be used to unregister this collator
+     * @stable ICU 2.6
+     */
+    static URegistryKey U_EXPORT2 registerFactory(CollatorFactory* toAdopt, UErrorCode& status);
+
+    /**
+     * Unregister a previously-registered Collator or CollatorFactory
+     * using the key returned from the register call.  Key becomes
+     * invalid after a successful call and should not be used again.
+     * The object corresponding to the key will be deleted.
+     * Because ICU may choose to cache collators internally, this should
+     * be called during application shutdown, after all calls to
+     * Collator::createInstance to avoid undefined behavior.
+     * @param key the registry key returned by a previous call to registerInstance
+     * @param status the in/out status code, no special meanings are assigned
+     * @return true if the collator for the key was successfully unregistered
+     * @stable ICU 2.6
+     */
+    static UBool U_EXPORT2 unregister(URegistryKey key, UErrorCode& status);
+#endif /* UCONFIG_NO_SERVICE */
+
+    /**
+     * Gets the version information for a Collator.
+     * @param info the version # information, the result will be filled in
+     * @stable ICU 2.0
+     */
+    virtual void getVersion(UVersionInfo info) const = 0;
+
+    /**
+     * Returns a unique class ID POLYMORPHICALLY. Pure virtual method.
+     * This method is to implement a simple version of RTTI, since not all C++
+     * compilers support genuine RTTI. Polymorphic operator==() and clone()
+     * methods call this method.
+     * @return The class ID for this object. All objects of a given class have
+     *         the same class ID.  Objects of other classes have different class
+     *         IDs.
+     * @stable ICU 2.0
+     */
+    virtual UClassID getDynamicClassID(void) const override = 0;
+
+    /**
+     * Universal attribute setter
+     * @param attr attribute type
+     * @param value attribute value
+     * @param status to indicate whether the operation went on smoothly or
+     *        there were errors
+     * @stable ICU 2.2
+     */
+    virtual void setAttribute(UColAttribute attr, UColAttributeValue value,
+                              UErrorCode &status) = 0;
+
+    /**
+     * Universal attribute getter
+     * @param attr attribute type
+     * @param status to indicate whether the operation went on smoothly or
+     *        there were errors
+     * @return attribute value
+     * @stable ICU 2.2
+     */
+    virtual UColAttributeValue getAttribute(UColAttribute attr,
+                                            UErrorCode &status) const = 0;
+
+    /**
+     * Sets the variable top to the top of the specified reordering group.
+     * The variable top determines the highest-sorting character
+     * which is affected by UCOL_ALTERNATE_HANDLING.
+     * If that attribute is set to UCOL_NON_IGNORABLE, then the variable top has no effect.
+     *
+     * The base class implementation sets U_UNSUPPORTED_ERROR.
+     * @param group one of UCOL_REORDER_CODE_SPACE, UCOL_REORDER_CODE_PUNCTUATION,
+     *              UCOL_REORDER_CODE_SYMBOL, UCOL_REORDER_CODE_CURRENCY;
+     *              or UCOL_REORDER_CODE_DEFAULT to restore the default max variable group
+     * @param errorCode Standard ICU error code. Its input value must
+     *                  pass the U_SUCCESS() test, or else the function returns
+     *                  immediately. Check for U_FAILURE() on output or use with
+     *                  function chaining. (See User Guide for details.)
+     * @return *this
+     * @see getMaxVariable
+     * @stable ICU 53
+     */
+    virtual Collator &setMaxVariable(UColReorderCode group, UErrorCode &errorCode);
+
+    /**
+     * Returns the maximum reordering group whose characters are affected by UCOL_ALTERNATE_HANDLING.
+     *
+     * The base class implementation returns UCOL_REORDER_CODE_PUNCTUATION.
+     * @return the maximum variable reordering group.
+     * @see setMaxVariable
+     * @stable ICU 53
+     */
+    virtual UColReorderCode getMaxVariable() const;
+
+#ifndef U_FORCE_HIDE_DEPRECATED_API
+    /**
+     * Sets the variable top to the primary weight of the specified string.
+     *
+     * Beginning with ICU 53, the variable top is pinned to
+     * the top of one of the supported reordering groups,
+     * and it must not be beyond the last of those groups.
+     * See setMaxVariable().
+     * @param varTop one or more (if contraction) char16_ts to which the variable top should be set
+     * @param len length of variable top string. If -1 it is considered to be zero terminated.
+     * @param status error code. If error code is set, the return value is undefined. Errors set by this function are: <br>
+     *    U_CE_NOT_FOUND_ERROR if more than one character was passed and there is no such contraction<br>
+     *    U_ILLEGAL_ARGUMENT_ERROR if the variable top is beyond
+     *    the last reordering group supported by setMaxVariable()
+     * @return variable top primary weight
+     * @deprecated ICU 53 Call setMaxVariable() instead.
+     */
+    virtual uint32_t setVariableTop(const char16_t *varTop, int32_t len, UErrorCode &status) = 0;
+
+    /**
+     * Sets the variable top to the primary weight of the specified string.
+     *
+     * Beginning with ICU 53, the variable top is pinned to
+     * the top of one of the supported reordering groups,
+     * and it must not be beyond the last of those groups.
+     * See setMaxVariable().
+     * @param varTop a UnicodeString size 1 or more (if contraction) of char16_ts to which the variable top should be set
+     * @param status error code. If error code is set, the return value is undefined. Errors set by this function are: <br>
+     *    U_CE_NOT_FOUND_ERROR if more than one character was passed and there is no such contraction<br>
+     *    U_ILLEGAL_ARGUMENT_ERROR if the variable top is beyond
+     *    the last reordering group supported by setMaxVariable()
+     * @return variable top primary weight
+     * @deprecated ICU 53 Call setMaxVariable() instead.
+     */
+    virtual uint32_t setVariableTop(const UnicodeString &varTop, UErrorCode &status) = 0;
+
+    /**
+     * Sets the variable top to the specified primary weight.
+     *
+     * Beginning with ICU 53, the variable top is pinned to
+     * the top of one of the supported reordering groups,
+     * and it must not be beyond the last of those groups.
+     * See setMaxVariable().
+     * @param varTop primary weight, as returned by setVariableTop or ucol_getVariableTop
+     * @param status error code
+     * @deprecated ICU 53 Call setMaxVariable() instead.
+     */
+    virtual void setVariableTop(uint32_t varTop, UErrorCode &status) = 0;
+#endif  // U_FORCE_HIDE_DEPRECATED_API
+
+    /**
+     * Gets the variable top value of a Collator.
+     * @param status error code (not changed by function). If error code is set, the return value is undefined.
+     * @return the variable top primary weight
+     * @see getMaxVariable
+     * @stable ICU 2.0
+     */
+    virtual uint32_t getVariableTop(UErrorCode &status) const = 0;
+
+    /**
+     * Get a UnicodeSet that contains all the characters and sequences
+     * tailored in this collator.
+     * @param status      error code of the operation
+     * @return a pointer to a UnicodeSet object containing all the
+     *         code points and sequences that may sort differently than
+     *         in the root collator. The object must be disposed of by using delete
+     * @stable ICU 2.4
+     */
+    virtual UnicodeSet *getTailoredSet(UErrorCode &status) const;
+
+#ifndef U_FORCE_HIDE_DEPRECATED_API
+    /**
+     * Same as clone().
+     * The base class implementation simply calls clone().
+     * @return a copy of this object, owned by the caller
+     * @see clone()
+     * @deprecated ICU 50 no need to have two methods for cloning
+     */
+    virtual Collator* safeClone() const;
+#endif  // U_FORCE_HIDE_DEPRECATED_API
+
+    /**
+     * Get the sort key as an array of bytes from a UnicodeString.
+     * Sort key byte arrays are zero-terminated and can be compared using
+     * strcmp().
+     *
+     * Note that sort keys are often less efficient than simply doing comparison.
+     * For more details, see the ICU User Guide.
+     *
+     * @param source string to be processed.
+     * @param result buffer to store result in. If nullptr, number of bytes needed
+     *        will be returned.
+     * @param resultLength length of the result buffer. If if not enough the
+     *        buffer will be filled to capacity.
+     * @return Number of bytes needed for storing the sort key
+     * @stable ICU 2.2
+     */
+    virtual int32_t getSortKey(const UnicodeString& source,
+                              uint8_t* result,
+                              int32_t resultLength) const = 0;
+
+    /**
+     * Get the sort key as an array of bytes from a char16_t buffer.
+     * Sort key byte arrays are zero-terminated and can be compared using
+     * strcmp().
+     *
+     * Note that sort keys are often less efficient than simply doing comparison.
+     * For more details, see the ICU User Guide.
+     *
+     * @param source string to be processed.
+     * @param sourceLength length of string to be processed.
+     *        If -1, the string is 0 terminated and length will be decided by the
+     *        function.
+     * @param result buffer to store result in. If nullptr, number of bytes needed
+     *        will be returned.
+     * @param resultLength length of the result buffer. If if not enough the
+     *        buffer will be filled to capacity.
+     * @return Number of bytes needed for storing the sort key
+     * @stable ICU 2.2
+     */
+    virtual int32_t getSortKey(const char16_t*source, int32_t sourceLength,
+                               uint8_t*result, int32_t resultLength) const = 0;
+
+    /**
+     * Produce a bound for a given sortkey and a number of levels.
+     * Return value is always the number of bytes needed, regardless of
+     * whether the result buffer was big enough or even valid.<br>
+     * Resulting bounds can be used to produce a range of strings that are
+     * between upper and lower bounds. For example, if bounds are produced
+     * for a sortkey of string "smith", strings between upper and lower
+     * bounds with one level would include "Smith", "SMITH", "sMiTh".<br>
+     * There are two upper bounds that can be produced. If UCOL_BOUND_UPPER
+     * is produced, strings matched would be as above. However, if bound
+     * produced using UCOL_BOUND_UPPER_LONG is used, the above example will
+     * also match "Smithsonian" and similar.<br>
+     * For more on usage, see example in cintltst/capitst.c in procedure
+     * TestBounds.
+     * Sort keys may be compared using <TT>strcmp</TT>.
+     * @param source The source sortkey.
+     * @param sourceLength The length of source, or -1 if null-terminated.
+     *                     (If an unmodified sortkey is passed, it is always null
+     *                      terminated).
+     * @param boundType Type of bound required. It can be UCOL_BOUND_LOWER, which
+     *                  produces a lower inclusive bound, UCOL_BOUND_UPPER, that
+     *                  produces upper bound that matches strings of the same length
+     *                  or UCOL_BOUND_UPPER_LONG that matches strings that have the
+     *                  same starting substring as the source string.
+     * @param noOfLevels  Number of levels required in the resulting bound (for most
+     *                    uses, the recommended value is 1). See users guide for
+     *                    explanation on number of levels a sortkey can have.
+     * @param result A pointer to a buffer to receive the resulting sortkey.
+     * @param resultLength The maximum size of result.
+     * @param status Used for returning error code if something went wrong. If the
+     *               number of levels requested is higher than the number of levels
+     *               in the source key, a warning (U_SORT_KEY_TOO_SHORT_WARNING) is
+     *               issued.
+     * @return The size needed to fully store the bound.
+     * @see ucol_keyHashCode
+     * @stable ICU 2.1
+     */
+    static int32_t U_EXPORT2 getBound(const uint8_t       *source,
+            int32_t             sourceLength,
+            UColBoundMode       boundType,
+            uint32_t            noOfLevels,
+            uint8_t             *result,
+            int32_t             resultLength,
+            UErrorCode          &status);
+
+
+protected:
+
+    // Collator protected constructors -------------------------------------
+
+    /**
+    * Default constructor.
+    * Constructor is different from the old default Collator constructor.
+    * The task for determining the default collation strength and normalization
+    * mode is left to the child class.
+    * @stable ICU 2.0
+    */
+    Collator();
+
+#ifndef U_HIDE_DEPRECATED_API
+    /**
+    * Constructor.
+    * Empty constructor, does not handle the arguments.
+    * This constructor is done for backward compatibility with 1.7 and 1.8.
+    * The task for handling the argument collation strength and normalization
+    * mode is left to the child class.
+    * @param collationStrength collation strength
+    * @param decompositionMode
+    * @deprecated ICU 2.4. Subclasses should use the default constructor
+    * instead and handle the strength and normalization mode themselves.
+    */
+    Collator(UCollationStrength collationStrength,
+             UNormalizationMode decompositionMode);
+#endif  /* U_HIDE_DEPRECATED_API */
+
+    /**
+    * Copy constructor.
+    * @param other Collator object to be copied from
+    * @stable ICU 2.0
+    */
+    Collator(const Collator& other);
+
+public:
+   /**
+    * Used internally by registration to define the requested and valid locales.
+    * @param requestedLocale the requested locale
+    * @param validLocale the valid locale
+    * @param actualLocale the actual locale
+    * @internal
+    */
+    virtual void setLocales(const Locale& requestedLocale, const Locale& validLocale, const Locale& actualLocale);
+
+    /** Get the short definition string for a collator. This internal API harvests the collator's
+     *  locale and the attribute set and produces a string that can be used for opening
+     *  a collator with the same attributes using the ucol_openFromShortString API.
+     *  This string will be normalized.
+     *  The structure and the syntax of the string is defined in the "Naming collators"
+     *  section of the users guide:
+     *  https://unicode-org.github.io/icu/userguide/collation/concepts#collator-naming-scheme
+     *  This function supports preflighting.
+     *
+     *  This is internal, and intended to be used with delegate converters.
+     *
+     *  @param locale a locale that will appear as a collators locale in the resulting
+     *                short string definition. If nullptr, the locale will be harvested
+     *                from the collator.
+     *  @param buffer space to hold the resulting string
+     *  @param capacity capacity of the buffer
+     *  @param status for returning errors. All the preflighting errors are featured
+     *  @return length of the resulting string
+     *  @see ucol_openFromShortString
+     *  @see ucol_normalizeShortDefinitionString
+     *  @see ucol_getShortDefinitionString
+     *  @internal
+     */
+    virtual int32_t internalGetShortDefinitionString(const char *locale,
+                                                     char *buffer,
+                                                     int32_t capacity,
+                                                     UErrorCode &status) const;
+
+    /**
+     * Implements ucol_strcollUTF8().
+     * @internal
+     */
+    virtual UCollationResult internalCompareUTF8(
+            const char *left, int32_t leftLength,
+            const char *right, int32_t rightLength,
+            UErrorCode &errorCode) const;
+
+    /**
+     * Implements ucol_nextSortKeyPart().
+     * @internal
+     */
+    virtual int32_t
+    internalNextSortKeyPart(
+            UCharIterator *iter, uint32_t state[2],
+            uint8_t *dest, int32_t count, UErrorCode &errorCode) const;
+
+#ifndef U_HIDE_INTERNAL_API
+    /** @internal */
+    static inline Collator *fromUCollator(UCollator *uc) {
+        return reinterpret_cast<Collator *>(uc);
+    }
+    /** @internal */
+    static inline const Collator *fromUCollator(const UCollator *uc) {
+        return reinterpret_cast<const Collator *>(uc);
+    }
+    /** @internal */
+    inline UCollator *toUCollator() {
+        return reinterpret_cast<UCollator *>(this);
+    }
+    /** @internal */
+    inline const UCollator *toUCollator() const {
+        return reinterpret_cast<const UCollator *>(this);
+    }
+#endif  // U_HIDE_INTERNAL_API
+
+private:
+    /**
+     * Assignment operator. Private for now.
+     */
+    Collator& operator=(const Collator& other) = delete;
+
+    friend class CFactory;
+    friend class SimpleCFactory;
+    friend class ICUCollatorFactory;
+    friend class ICUCollatorService;
+    static Collator* makeInstance(const Locale& desiredLocale,
+                                  UErrorCode& status);
+};
+
+#if !UCONFIG_NO_SERVICE
+/**
+ * A factory, used with registerFactory, the creates multiple collators and provides
+ * display names for them.  A factory supports some number of locales-- these are the
+ * locales for which it can create collators.  The factory can be visible, in which
+ * case the supported locales will be enumerated by getAvailableLocales, or invisible,
+ * in which they are not.  Invisible locales are still supported, they are just not
+ * listed by getAvailableLocales.
+ * <p>
+ * If standard locale display names are sufficient, Collator instances can
+ * be registered using registerInstance instead.</p>
+ * <p>
+ * Note: if the collators are to be used from C APIs, they must be instances
+ * of RuleBasedCollator.</p>
+ *
+ * @stable ICU 2.6
+ */
+class U_I18N_API CollatorFactory : public UObject {
+public:
+
+    /**
+     * Destructor
+     * @stable ICU 3.0
+     */
+    virtual ~CollatorFactory();
+
+    /**
+     * Return true if this factory is visible.  Default is true.
+     * If not visible, the locales supported by this factory will not
+     * be listed by getAvailableLocales.
+     * @return true if the factory is visible.
+     * @stable ICU 2.6
+     */
+    virtual UBool visible(void) const;
+
+    /**
+     * Return a collator for the provided locale.  If the locale
+     * is not supported, return nullptr.
+     * @param loc the locale identifying the collator to be created.
+     * @return a new collator if the locale is supported, otherwise nullptr.
+     * @stable ICU 2.6
+     */
+    virtual Collator* createCollator(const Locale& loc) = 0;
+
+    /**
+     * Return the name of the collator for the objectLocale, localized for the displayLocale.
+     * If objectLocale is not supported, or the factory is not visible, set the result string
+     * to bogus.
+     * @param objectLocale the locale identifying the collator
+     * @param displayLocale the locale for which the display name of the collator should be localized
+     * @param result an output parameter for the display name, set to bogus if not supported.
+     * @return the display name
+     * @stable ICU 2.6
+     */
+    virtual  UnicodeString& getDisplayName(const Locale& objectLocale,
+                                           const Locale& displayLocale,
+                                           UnicodeString& result);
+
+    /**
+     * Return an array of all the locale names directly supported by this factory.
+     * The number of names is returned in count.  This array is owned by the factory.
+     * Its contents must never change.
+     * @param count output parameter for the number of locales supported by the factory
+     * @param status the in/out error code
+     * @return a pointer to an array of count UnicodeStrings.
+     * @stable ICU 2.6
+     */
+    virtual const UnicodeString * getSupportedIDs(int32_t &count, UErrorCode& status) = 0;
+};
+#endif /* UCONFIG_NO_SERVICE */
+
+// Collator inline methods -----------------------------------------------
+
+U_NAMESPACE_END
+
+#endif /* #if !UCONFIG_NO_COLLATION */
+
+#endif /* U_SHOW_CPLUSPLUS_API */
+
+#endif