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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() 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() 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();
- /**
- * Resets this CollationKey to an empty state
- * @return this CollationKey
- */
- CollationKey& reset();
- /**
- * 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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