/*
******************************************************************************
*   Copyright (C) 1996-2006, International Business Machines                 *
*   Corporation and others.  All Rights Reserved.                            *
******************************************************************************
*/

/**
* 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
*                          (ucoll.h).
*/

#ifndef COLL_H
#define COLL_H

#include "unicode/utypes.h"

/**
 * \file 
 * \brief C++ API: Collation Service.
 */
 
#if !UCONFIG_NO_COLLATION

#include "unicode/uobject.h"
#include "unicode/ucol.h"
#include "unicode/normlzr.h"
#include "unicode/locid.h"
#include "unicode/uniset.h"
#include "unicode/umisc.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.<br>
* <em>Important: </em>The ICU collation service has been reimplemented
* in order to achieve better performance and UCA compliance.
* For details, see the
* <a href="http://dev.icu-project.org/cgi-bin/viewcvs.cgi/~checkout~/icuhtml/design/collation/ICU_collation_design.htm">
* collation design document</a>.
* <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> property 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 dependant.
* 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::US, 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
* <p>
* For comparing strings exactly once, the <code>compare</code> method
* provides the best performance. When sorting a list of strings however, it
* is generally necessary to compare each string multiple times. In this case,
* sort keys provide better performance. 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. They consist of several substrings, one for
* each collation strength level, that are delimited by 0x01 bytes.
* If the string code points are appended for UCOL_IDENTICAL, then they are
* processed for correct code point order comparison and may contain 0x01
* bytes but not zero bytes.
* </p>
* <p>
* An older set of APIs returns a <code>CollationKey</code> object that wraps
* the sort key bytes instead of returning the bytes themselves.
* Its use is deprecated, but it is still available for compatibility with
* Java.
* </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         Normalizer
* @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    = 0,
        SECONDARY  = 1,
        TERTIARY   = 2,
        QUATERNARY = 3,
        IDENTICAL  = 15
    };

    /**
     * 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 = -1,
        EQUAL = 0,
        GREATER = 1
    };

    // Collator public destructor -----------------------------------------

    /**
     * Destructor
     * @stable ICU 2.0
     */
    virtual ~Collator();

    // Collator public methods --------------------------------------------

    /**
     * Returns true if "other" is the same as "this"
     * @param other Collator object to be compared
     * @return true if other is the same as this.
     * @stable ICU 2.0
     */
    virtual UBool operator==(const Collator& other) const;

    /**
     * Returns true if "other" is not the same as "this".
     * @param other Collator object to be compared
     * @return true if other is not the same as this.
     * @stable ICU 2.0
     */
    virtual UBool operator!=(const Collator& other) const;

    /**
     * Makes a shallow copy of the current object.
     * @return a copy of this object
     * @stable ICU 2.0
     */
    virtual Collator* clone(void) 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 table-based collation object for the desired locale. The
     * resource of the desired locale will be loaded by ResourceLoader.
     * Locale::ENGLISH is the base collation table and all other languages are
     * built on top of it with additional language-specific modifications.
     * 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);

#ifdef U_USE_COLLATION_OBSOLETE_2_6
    /**
     * Create a Collator with a specific version.
     * This is the same as createInstance(loc, err) except that getVersion() of
     * the returned object is guaranteed to be the same as the version
     * parameter.
     * This is designed to be used to open the same collator for a given
     * locale even when ICU is updated.
     * The same locale and version guarantees the same sort keys and
     * comparison results.
     * <p>
     * Note: this API will be removed in a future release.  Use
     * <tt>createInstance(const Locale&, UErrorCode&) instead.</tt></p>
     *
     * @param loc The locale ID for which to open a collator.
     * @param version The requested collator version.
     * @param err A reference to a UErrorCode,
     *            must not indicate a failure before calling this function.
     * @return A pointer to a Collator, or 0 if an error occurred
     *         or a collator with the requested version is not available.
     *
     * @see getVersion
     * @obsolete ICU 2.6
     */
    static Collator *createInstance(const Locale &loc, UVersionInfo version, UErrorCode &err);
#endif

    /**
     * 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;

    /**
     * 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;

    /**
     * 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;

    /**
     * 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;

    /**
     * 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.
     * @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 UChar* source, int32_t sourceLength,
                                      const UChar* target, int32_t targetLength)
                                      const;

    /**
     * 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 UChar* source, int32_t sourceLength,
                                      const UChar* target, int32_t targetLength,
                                      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.  The generated sort key handles
     * only a limited number of ignorable characters.
     * <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.
     * @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
     * @deprecated ICU 2.8 Use getSortKey(...) instead
     */
    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.  The generated sort key handles
     * only a limited number of ignorable characters.
     * <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.
     * @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
     * @deprecated ICU 2.8 Use getSortKey(...) instead
     */
    virtual CollationKey& getCollationKey(const UChar*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;

    /**
     * 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 const Locale getLocale(ULocDataLocaleType type, UErrorCode& status) const = 0;

    /**
     * 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;

    /**
     * Determines the minimum strength that will be use 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 = 0;

    /**
     * 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::US, 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) = 0;

    /**
     * Get name of the object for the desired Locale, in the desired langauge
     * @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 langauge 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);

#if !UCONFIG_NO_SERVICE
    /**
     * 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);
#endif

    /**
     * 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 NULL
     * upon error. The caller is responsible for deleting the result.
     * @stable ICU 3.0
     */
    static StringEnumeration* U_EXPORT2 getKeywordValues(const char *keyword, 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="http://icu.sourceforge.net/userguide/locale.html#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.
     * @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.
     * @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.
     * @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 = 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) = 0;

    /**
     * Sets the variable top to a collation element value of a string supplied.
     * @param varTop one or more (if contraction) UChars 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 a contraction<br>
     *    U_PRIMARY_TOO_LONG_ERROR if the primary for the variable top has more than two bytes
     * @return a 32 bit value containing the value of the variable top in upper 16 bits. Lower 16 bits are undefined
     * @stable ICU 2.0
     */
    virtual uint32_t setVariableTop(const UChar *varTop, int32_t len, UErrorCode &status) = 0;

    /**
     * Sets the variable top to a collation element value of a string supplied.
     * @param varTop an UnicodeString size 1 or more (if contraction) of UChars 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 a contraction<br>
     *    U_PRIMARY_TOO_LONG_ERROR if the primary for the variable top has more than two bytes
     * @return a 32 bit value containing the value of the variable top in upper 16 bits. Lower 16 bits are undefined
     * @stable ICU 2.0
     */
    virtual uint32_t setVariableTop(const UnicodeString varTop, UErrorCode &status) = 0;

    /**
     * Sets the variable top to a collation element value supplied. Variable top is set to the upper 16 bits.
     * Lower 16 bits are ignored.
     * @param varTop CE value, as returned by setVariableTop or ucol)getVariableTop
     * @param status error code (not changed by function)
     * @stable ICU 2.0
     */
    virtual void setVariableTop(const uint32_t varTop, UErrorCode &status) = 0;

    /**
     * Gets the variable top value of a Collator.
     * Lower 16 bits are undefined and should be ignored.
     * @param status error code (not changed by function). If error code is set, the return value is undefined.
     * @stable ICU 2.0
     */
    virtual uint32_t getVariableTop(UErrorCode &status) const = 0;

    /**
     * Get an 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 UCA. The object must be disposed of by using delete
     * @stable ICU 2.4
     */
    virtual UnicodeSet *getTailoredSet(UErrorCode &status) const;


    /**
     * Thread safe cloning operation
     * @return pointer to the new clone, user should remove it.
     * @stable ICU 2.2
     */
    virtual Collator* safeClone(void) = 0;

    /**
     * Get the sort key as an array of bytes from an UnicodeString.
     * Sort key byte arrays are zero-terminated and can be compared using
     * strcmp().
     * @param source string to be processed.
     * @param result buffer to store result in. If NULL, 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 an UChar buffer.
     * Sort key byte arrays are zero-terminated and can be compared using
     * strcmp().
     * @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 NULL, 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 UChar*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 determing the default collation strength and normalization
    * mode is left to the child class.
    * @stable ICU 2.0
    */
    Collator();

    /**
    * 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);

    /**
    * Copy constructor.
    * @param other Collator object to be copied from
    * @stable ICU 2.0
    */
    Collator(const Collator& other);

    // Collator protected methods -----------------------------------------


   /**
    * Used internally by registraton to define the requested and valid locales.
    * @param requestedLocale the requsted locale
    * @param validLocale the valid locale
    * @internal
    */
    virtual void setLocales(const Locale& requestedLocale, const Locale& validLocale);

public:
#if !UCONFIG_NO_SERVICE
    /**
     * used only by ucol_open, not for public use
     * @internal
     */
    static UCollator* createUCollator(const char* loc, UErrorCode* status);
#endif
private:
    /**
     * Assignment operator. Private for now.
     * @internal
     */
    Collator& operator=(const Collator& other);

    friend class CFactory;
    friend class SimpleCFactory;
    friend class ICUCollatorFactory;
    friend class ICUCollatorService;
    static Collator* makeInstance(const Locale& desiredLocale,
                                  UErrorCode& status);

    // Collator private data members ---------------------------------------

    /*
    synwee : removed as attributes to be handled by child class
    UCollationStrength  strength;
    Normalizer::EMode  decmp;
    */
    /* This is useless information */
/*  static const UVersionInfo fVersion;*/
};

#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 NULL.
     * @param loc the locale identifying the collator to be created.
     * @return a new collator if the locale is supported, otherwise NULL.
     * @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