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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 < 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 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 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 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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