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 // © 2016 and later: Unicode, Inc. and others.
 // License & terms of use: http://www.unicode.org/copyright.html
 /*
  *****************************************************************************
  * Copyright (C) 1996-2014, International Business Machines Corporation and others.
  * All Rights Reserved.
  *****************************************************************************
  *
  * File sortkey.h
  *
  * Created by: Helena Shih
  *
  * Modification History:
  *
  *  Date         Name          Description
  *
  *  6/20/97     helena      Java class name change.
  *  8/18/97     helena      Added internal API documentation.
  *  6/26/98     erm         Changed to use byte arrays and memcmp.
  *****************************************************************************
  */
 
 #ifndef SORTKEY_H
 #define SORTKEY_H
 
 #include "unicode/utypes.h"
 
 #if U_SHOW_CPLUSPLUS_API
 
 /**
  * \file 
  * \brief C++ API: Keys for comparing strings multiple times. 
  */
  
 #if !UCONFIG_NO_COLLATION
 
 #include "unicode/uobject.h"
 #include "unicode/unistr.h"
 #include "unicode/coll.h"
 
 U_NAMESPACE_BEGIN
 
 /* forward declaration */
 class RuleBasedCollator;
 class CollationKeyByteSink;
 
 /**
  *
  * Collation keys are generated by the Collator class.  Use the CollationKey objects
  * instead of Collator to compare strings multiple times.  A CollationKey
  * preprocesses the comparison information from the Collator object to
  * make the comparison faster.  If you are not going to comparing strings
  * multiple times, then using the Collator object is generally faster,
  * since it only processes as much of the string as needed to make a
  * comparison.
  * <p> For example (with strength == tertiary)
  * <p>When comparing "Abernathy" to "Baggins-Smythworthy", Collator
  * only needs to process a couple of characters, while a comparison
  * with CollationKeys will process all of the characters.  On the other hand,
  * if you are doing a sort of a number of fields, it is much faster to use
  * CollationKeys, since you will be comparing strings multiple times.
  * <p>Typical use of CollationKeys are in databases, where you store a CollationKey
  * in a hidden field, and use it for sorting or indexing.
  *
  * <p>Example of use:
  * <pre>
  * \code
  *     UErrorCode success = U_ZERO_ERROR;
  *     Collator* myCollator = Collator::createInstance(success);
  *     CollationKey* keys = new CollationKey [3];
  *     myCollator->getCollationKey("Tom", keys[0], success );
  *     myCollator->getCollationKey("Dick", keys[1], success );
  *     myCollator->getCollationKey("Harry", keys[2], success );
  *
  *     // Inside body of sort routine, compare keys this way:
  *     CollationKey tmp;
  *     if(keys[0].compareTo( keys[1] ) > 0 ) {
  *         tmp = keys[0]; keys[0] = keys[1]; keys[1] = tmp;
  *     }
  *     //...
  * \endcode
  * </pre>
  * <p>Because Collator::compare()'s algorithm is complex, it is faster to sort
  * long lists of words by retrieving collation keys with Collator::getCollationKey().
  * You can then cache the collation keys and compare them using CollationKey::compareTo().
  * <p>
  * <strong>Note:</strong> <code>Collator</code>s with different Locale,
  * CollationStrength and DecompositionMode settings will return different
  * CollationKeys 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 different CollationKeys
  * for same strings.
  * <p>
 
  * @see          Collator
  * @see          RuleBasedCollator
  * @version      1.3 12/18/96
  * @author       Helena Shih
  * @stable ICU 2.0
  */
 class U_I18N_API CollationKey : public UObject {
 public:
     /**
     * This creates an empty collation key based on the null string.  An empty
     * collation key contains no sorting information.  When comparing two empty
     * collation keys, the result is Collator::EQUAL.  Comparing empty collation key
     * with non-empty collation key is always Collator::LESS.
     * @stable ICU 2.0
     */
     CollationKey();
 
 
     /**
     * Creates a collation key based on the collation key values.
     * @param values the collation key values
     * @param count number of collation key values, including trailing nulls.
     * @stable ICU 2.0
     */
     CollationKey(const  uint8_t*    values,
                 int32_t     count);
 
     /**
     * Copy constructor.
     * @param other    the object to be copied.
     * @stable ICU 2.0
     */
     CollationKey(const CollationKey& other);
 
     /**
     * Sort key destructor.
     * @stable ICU 2.0
     */
     virtual ~CollationKey();
 
     /**
     * Assignment operator
     * @param other    the object to be copied.
     * @stable ICU 2.0
     */
     const   CollationKey&   operator=(const CollationKey& other);
 
     /**
     * Compare if two collation keys are the same.
     * @param source the collation key to compare to.
     * @return Returns true if two collation keys are equal, false otherwise.
     * @stable ICU 2.0
     */
     bool                    operator==(const CollationKey& source) const;
 
     /**
     * Compare if two collation keys are not the same.
     * @param source the collation key to compare to.
     * @return Returns true if two collation keys are different, false otherwise.
     * @stable ICU 2.0
     */
     bool                    operator!=(const CollationKey& source) const;
 
 
     /**
     * Test to see if the key is in an invalid state. The key will be in an
     * invalid state if it couldn't allocate memory for some operation.
     * @return Returns true if the key is in an invalid, false otherwise.
     * @stable ICU 2.0
     */
     UBool                   isBogus(void) const;
 
     /**
     * Returns a pointer to the collation key values. The storage is owned
     * by the collation key and the pointer will become invalid if the key
     * is deleted.
     * @param count the output parameter of number of collation key values,
     * including any trailing nulls.
     * @return a pointer to the collation key values.
     * @stable ICU 2.0
     */
     const    uint8_t*       getByteArray(int32_t& count) const;
 
 #ifdef U_USE_COLLATION_KEY_DEPRECATES
     /**
     * Extracts the collation key values into a new array. The caller owns
     * this storage and should free it.
     * @param count the output parameter of number of collation key values,
     * including any trailing nulls.
     * @obsolete ICU 2.6. Use getByteArray instead since this API will be removed in that release.
     */
     uint8_t*                toByteArray(int32_t& count) const;
 #endif
 
 #ifndef U_HIDE_DEPRECATED_API 
     /**
     * Convenience method which does a string(bit-wise) comparison of the
     * two collation keys.
     * @param target target collation key to be compared with
     * @return Returns Collator::LESS if sourceKey &lt; targetKey,
     * Collator::GREATER if sourceKey > targetKey and Collator::EQUAL
     * otherwise.
     * @deprecated ICU 2.6 use the overload with error code
     */
     Collator::EComparisonResult compareTo(const CollationKey& target) const;
 #endif  /* U_HIDE_DEPRECATED_API */
 
     /**
     * Convenience method which does a string(bit-wise) comparison of the
     * two collation keys.
     * @param target target collation key to be compared with
     * @param status error code
     * @return Returns UCOL_LESS if sourceKey &lt; targetKey,
     * UCOL_GREATER if sourceKey > targetKey and UCOL_EQUAL
     * otherwise.
     * @stable ICU 2.6
     */
     UCollationResult compareTo(const CollationKey& target, UErrorCode &status) const;
 
     /**
     * Creates an integer that is unique to the collation key.  NOTE: this
     * is not the same as String.hashCode.
     * <p>Example of use:
     * <pre>
     * .    UErrorCode status = U_ZERO_ERROR;
     * .    Collator *myCollation = Collator::createInstance(Locale::US, status);
     * .    if (U_FAILURE(status)) return;
     * .    CollationKey key1, key2;
     * .    UErrorCode status1 = U_ZERO_ERROR, status2 = U_ZERO_ERROR;
     * .    myCollation->getCollationKey("abc", key1, status1);
     * .    if (U_FAILURE(status1)) { delete myCollation; return; }
     * .    myCollation->getCollationKey("ABC", key2, status2);
     * .    if (U_FAILURE(status2)) { delete myCollation; return; }
     * .    // key1.hashCode() != key2.hashCode()
     * </pre>
     * @return the hash value based on the string's collation order.
     * @see UnicodeString#hashCode
     * @stable ICU 2.0
     */
     int32_t                 hashCode(void) const;
 
     /**
      * ICU "poor man's RTTI", returns a UClassID for the actual class.
      * @stable ICU 2.2
      */
     virtual UClassID getDynamicClassID() const override;
 
     /**
      * ICU "poor man's RTTI", returns a UClassID for this class.
      * @stable ICU 2.2
      */
     static UClassID U_EXPORT2 getStaticClassID();
 
 private:
     /**
      * Replaces the current bytes buffer with a new one of newCapacity
      * and copies length bytes from the old buffer to the new one.
      * @return the new buffer, or nullptr if the allocation failed
      */
     uint8_t *reallocate(int32_t newCapacity, int32_t length);
     /**
      * Set a new length for a new sort key in the existing fBytes.
      */
     void setLength(int32_t newLength);
 
     uint8_t *getBytes() {
         return (fFlagAndLength >= 0) ? fUnion.fStackBuffer : fUnion.fFields.fBytes;
     }
     const uint8_t *getBytes() const {
         return (fFlagAndLength >= 0) ? fUnion.fStackBuffer : fUnion.fFields.fBytes;
     }
     int32_t getCapacity() const {
         return (fFlagAndLength >= 0) ? (int32_t)sizeof(fUnion) : fUnion.fFields.fCapacity;
     }
     int32_t getLength() const { return fFlagAndLength & 0x7fffffff; }
 
     /**
     * Set the CollationKey to a "bogus" or invalid state
     * @return this CollationKey
     */
     CollationKey&           setToBogus(void);
     /**
     * Resets this CollationKey to an empty state
     * @return this CollationKey
     */
     CollationKey&           reset(void);
 
     /**
     * Allow private access to RuleBasedCollator
     */
     friend  class           RuleBasedCollator;
     friend  class           CollationKeyByteSink;
 
     // Class fields. sizeof(CollationKey) is intended to be 48 bytes
     // on a machine with 64-bit pointers.
     // We use a union to maximize the size of the internal buffer,
     // similar to UnicodeString but not as tight and complex.
 
     // (implicit) *vtable;
     /**
      * Sort key length and flag.
      * Bit 31 is set if the buffer is heap-allocated.
      * Bits 30..0 contain the sort key length.
      */
     int32_t fFlagAndLength;
     /**
     * Unique hash value of this CollationKey.
     * Special value 2 if the key is bogus.
     */
     mutable int32_t fHashCode;
     /**
      * fUnion provides 32 bytes for the internal buffer or for
      * pointer+capacity.
      */
     union StackBufferOrFields {
         /** fStackBuffer is used iff fFlagAndLength>=0, else fFields is used */
         uint8_t fStackBuffer[32];
         struct {
             uint8_t *fBytes;
             int32_t fCapacity;
         } fFields;
     } fUnion;
 };
 
 inline bool
 CollationKey::operator!=(const CollationKey& other) const
 {
     return !(*this == other);
 }
 
 inline UBool
 CollationKey::isBogus() const
 {
     return fHashCode == 2;  // kBogusHashCode
 }
 
 inline const uint8_t*
 CollationKey::getByteArray(int32_t &count) const
 {
     count = getLength();
     return getBytes();
 }
 
 U_NAMESPACE_END
 
 #endif /* #if !UCONFIG_NO_COLLATION */
 
 #endif /* U_SHOW_CPLUSPLUS_API */
 
 #endif

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