For example (with strength == tertiary) *
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. *
Typical use of CollationKeys are in databases, where you store a CollationKey * in a hidden field, and use it for sorting or indexing. * *
Example of use: *
* \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
*
* 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(). *
* Note: Collators 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.
*
* @see Collator * @see RuleBasedCollator * @version 1.3 12/18/96 * @author Helena Shih * @deprecated ICU 2.8 Use Collator::getSortKey(...) instead */ 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. * @deprecated ICU 2.8 Use Collator::getSortKey(...) instead */ 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. * @deprecated ICU 2.8 Use Collator::getSortKey(...) instead */ CollationKey(const uint8_t* values, int32_t count); /** * Copy constructor. * @param other the object to be copied. * @deprecated ICU 2.8 Use Collator::getSortKey(...) instead */ CollationKey(const CollationKey& other); /** * Sort key destructor. * @deprecated ICU 2.8 Use Collator::getSortKey(...) instead */ virtual ~CollationKey(); /** * Assignment operator * @param other the object to be copied. * @deprecated ICU 2.8 Use Collator::getSortKey(...) instead */ 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. * @deprecated ICU 2.8 Use Collator::getSortKey(...) instead */ 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. * @deprecated ICU 2.8 Use Collator::getSortKey(...) instead */ 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. * @deprecated ICU 2.8 Use Collator::getSortKey(...) instead */ 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. * @deprecated ICU 2.8 Use Collator::getSortKey(...) instead */ 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 /** * 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; /** * 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. * @deprecated ICU 2.8 Use Collator::getSortKey(...) instead */ 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. *
Example of use: *
* . 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()
*
* @return the hash value based on the string's collation order.
* @see UnicodeString#hashCode
* @deprecated ICU 2.8 Use Collator::getSortKey(...) instead
*/
int32_t hashCode(void) const;
/**
* ICU "poor man's RTTI", returns a UClassID for the actual class.
* @deprecated ICU 2.8 Use Collator::getSortKey(...) instead
*/
virtual UClassID getDynamicClassID() const;
/**
* ICU "poor man's RTTI", returns a UClassID for this class.
* @deprecated ICU 2.8 Use Collator::getSortKey(...) instead
*/
static UClassID U_EXPORT2 getStaticClassID();
private:
/**
* Returns an array of the collation key values as 16-bit integers.
* The caller owns the storage and must delete it.
* @param values Output param of the collation key values.
* @param count output parameter of the number of collation key values
* @return a pointer to an array of 16-bit collation key values.
*/
void adopt(uint8_t *values, int32_t count);
/*
* Creates a collation key with a string.
*/
/**
* If this CollationKey has capacity less than newSize,
* its internal capacity will be increased to newSize.
* @param newSize minimum size this CollationKey has to have
* @return this CollationKey
*/
CollationKey& ensureCapacity(int32_t newSize);
/**
* 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;
/**
* Bogus status
*/
UBool fBogus;
/**
* Size of fBytes used to store the sortkey. i.e. up till the
* null-termination.
*/
int32_t fCount;
/**
* Full size of the fBytes
*/
int32_t fCapacity;
/**
* Unique hash value of this CollationKey
*/
int32_t fHashCode;
/**
* Array to store the sortkey
*/
uint8_t* fBytes;
};
inline UBool
CollationKey::operator!=(const CollationKey& other) const
{
return !(*this == other);
}
inline UBool
CollationKey::isBogus() const
{
return fBogus;
}
inline const uint8_t*
CollationKey::getByteArray(int32_t &count) const
{
count = fCount;
return fBytes;
}
U_NAMESPACE_END
#endif /* #if !UCONFIG_NO_COLLATION */
#endif