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 /*

  *****************************************************************************

  * Copyright (C) 1996-2013, 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"

 /**

  * \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;

 /**

  *

  * 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

     */

     UBool                   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

     */

     UBool                   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 < 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 < 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;

     /**

      * 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 NULL 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 UBool

 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