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/usr/include/unicode/sortkey.h
$ cat -n /usr/include/unicode/sortkey.h 1 // © 2016 and later: Unicode, Inc. and others. 2 // License & terms of use: http://www.unicode.org/copyright.html 3 /* 4 ***************************************************************************** 5 * Copyright (C) 1996-2014, International Business Machines Corporation and others. 6 * All Rights Reserved. 7 ***************************************************************************** 8 * 9 * File sortkey.h 10 * 11 * Created by: Helena Shih 12 * 13 * Modification History: 14 * 15 * Date Name Description 16 * 17 * 6/20/97 helena Java class name change. 18 * 8/18/97 helena Added internal API documentation. 19 * 6/26/98 erm Changed to use byte arrays and memcmp. 20 ***************************************************************************** 21 */ 22 23 #ifndef SORTKEY_H 24 #define SORTKEY_H 25 26 #include "unicode/utypes.h" 27 28 #if U_SHOW_CPLUSPLUS_API 29 30 /** 31 * \file 32 * \brief C++ API: Keys for comparing strings multiple times. 33 */ 34 35 #if !UCONFIG_NO_COLLATION 36 37 #include "unicode/uobject.h" 38 #include "unicode/unistr.h" 39 #include "unicode/coll.h" 40 41 U_NAMESPACE_BEGIN 42 43 /* forward declaration */ 44 class RuleBasedCollator; 45 class CollationKeyByteSink; 46 47 /** 48 * 49 * Collation keys are generated by the Collator class. Use the CollationKey objects 50 * instead of Collator to compare strings multiple times. A CollationKey 51 * preprocesses the comparison information from the Collator object to 52 * make the comparison faster. If you are not going to comparing strings 53 * multiple times, then using the Collator object is generally faster, 54 * since it only processes as much of the string as needed to make a 55 * comparison. 56 * <p> For example (with strength == tertiary) 57 * <p>When comparing "Abernathy" to "Baggins-Smythworthy", Collator 58 * only needs to process a couple of characters, while a comparison 59 * with CollationKeys will process all of the characters. On the other hand, 60 * if you are doing a sort of a number of fields, it is much faster to use 61 * CollationKeys, since you will be comparing strings multiple times. 62 * <p>Typical use of CollationKeys are in databases, where you store a CollationKey 63 * in a hidden field, and use it for sorting or indexing. 64 * 65 * <p>Example of use: 66 * <pre> 67 * \code 68 * UErrorCode success = U_ZERO_ERROR; 69 * Collator* myCollator = Collator::createInstance(success); 70 * CollationKey* keys = new CollationKey [3]; 71 * myCollator->getCollationKey("Tom", keys[0], success ); 72 * myCollator->getCollationKey("Dick", keys[1], success ); 73 * myCollator->getCollationKey("Harry", keys[2], success ); 74 * 75 * // Inside body of sort routine, compare keys this way: 76 * CollationKey tmp; 77 * if(keys[0].compareTo( keys[1] ) > 0 ) { 78 * tmp = keys[0]; keys[0] = keys[1]; keys[1] = tmp; 79 * } 80 * //... 81 * \endcode 82 * </pre> 83 * <p>Because Collator::compare()'s algorithm is complex, it is faster to sort 84 * long lists of words by retrieving collation keys with Collator::getCollationKey(). 85 * You can then cache the collation keys and compare them using CollationKey::compareTo(). 86 * <p> 87 * <strong>Note:</strong> <code>Collator</code>s with different Locale, 88 * CollationStrength and DecompositionMode settings will return different 89 * CollationKeys for the same set of strings. Locales have specific 90 * collation rules, and the way in which secondary and tertiary differences 91 * are taken into account, for example, will result in different CollationKeys 92 * for same strings. 93 * <p> 94 95 * @see Collator 96 * @see RuleBasedCollator 97 * @version 1.3 12/18/96 98 * @author Helena Shih 99 * @stable ICU 2.0 100 */ 101 class U_I18N_API CollationKey : public UObject { 102 public: 103 /** 104 * This creates an empty collation key based on the null string. An empty 105 * collation key contains no sorting information. When comparing two empty 106 * collation keys, the result is Collator::EQUAL. Comparing empty collation key 107 * with non-empty collation key is always Collator::LESS. 108 * @stable ICU 2.0 109 */ 110 CollationKey(); 111 112 113 /** 114 * Creates a collation key based on the collation key values. 115 * @param values the collation key values 116 * @param count number of collation key values, including trailing nulls. 117 * @stable ICU 2.0 118 */ 119 CollationKey(const uint8_t* values, 120 int32_t count); 121 122 /** 123 * Copy constructor. 124 * @param other the object to be copied. 125 * @stable ICU 2.0 126 */ 127 CollationKey(const CollationKey& other); 128 129 /** 130 * Sort key destructor. 131 * @stable ICU 2.0 132 */ 133 virtual ~CollationKey(); 134 135 /** 136 * Assignment operator 137 * @param other the object to be copied. 138 * @stable ICU 2.0 139 */ 140 const CollationKey& operator=(const CollationKey& other); 141 142 /** 143 * Compare if two collation keys are the same. 144 * @param source the collation key to compare to. 145 * @return Returns true if two collation keys are equal, false otherwise. 146 * @stable ICU 2.0 147 */ 148 bool operator==(const CollationKey& source) const; 149 150 /** 151 * Compare if two collation keys are not the same. 152 * @param source the collation key to compare to. 153 * @return Returns true if two collation keys are different, false otherwise. 154 * @stable ICU 2.0 155 */ 156 bool operator!=(const CollationKey& source) const; 157 158 159 /** 160 * Test to see if the key is in an invalid state. The key will be in an 161 * invalid state if it couldn't allocate memory for some operation. 162 * @return Returns true if the key is in an invalid, false otherwise. 163 * @stable ICU 2.0 164 */ 165 UBool isBogus(void) const; 166 167 /** 168 * Returns a pointer to the collation key values. The storage is owned 169 * by the collation key and the pointer will become invalid if the key 170 * is deleted. 171 * @param count the output parameter of number of collation key values, 172 * including any trailing nulls. 173 * @return a pointer to the collation key values. 174 * @stable ICU 2.0 175 */ 176 const uint8_t* getByteArray(int32_t& count) const; 177 178 #ifdef U_USE_COLLATION_KEY_DEPRECATES 179 /** 180 * Extracts the collation key values into a new array. The caller owns 181 * this storage and should free it. 182 * @param count the output parameter of number of collation key values, 183 * including any trailing nulls. 184 * @obsolete ICU 2.6. Use getByteArray instead since this API will be removed in that release. 185 */ 186 uint8_t* toByteArray(int32_t& count) const; 187 #endif 188 189 #ifndef U_HIDE_DEPRECATED_API 190 /** 191 * Convenience method which does a string(bit-wise) comparison of the 192 * two collation keys. 193 * @param target target collation key to be compared with 194 * @return Returns Collator::LESS if sourceKey < targetKey, 195 * Collator::GREATER if sourceKey > targetKey and Collator::EQUAL 196 * otherwise. 197 * @deprecated ICU 2.6 use the overload with error code 198 */ 199 Collator::EComparisonResult compareTo(const CollationKey& target) const; 200 #endif /* U_HIDE_DEPRECATED_API */ 201 202 /** 203 * Convenience method which does a string(bit-wise) comparison of the 204 * two collation keys. 205 * @param target target collation key to be compared with 206 * @param status error code 207 * @return Returns UCOL_LESS if sourceKey < targetKey, 208 * UCOL_GREATER if sourceKey > targetKey and UCOL_EQUAL 209 * otherwise. 210 * @stable ICU 2.6 211 */ 212 UCollationResult compareTo(const CollationKey& target, UErrorCode &status) const; 213 214 /** 215 * Creates an integer that is unique to the collation key. NOTE: this 216 * is not the same as String.hashCode. 217 * <p>Example of use: 218 * <pre> 219 * . UErrorCode status = U_ZERO_ERROR; 220 * . Collator *myCollation = Collator::createInstance(Locale::US, status); 221 * . if (U_FAILURE(status)) return; 222 * . CollationKey key1, key2; 223 * . UErrorCode status1 = U_ZERO_ERROR, status2 = U_ZERO_ERROR; 224 * . myCollation->getCollationKey("abc", key1, status1); 225 * . if (U_FAILURE(status1)) { delete myCollation; return; } 226 * . myCollation->getCollationKey("ABC", key2, status2); 227 * . if (U_FAILURE(status2)) { delete myCollation; return; } 228 * . // key1.hashCode() != key2.hashCode() 229 * </pre> 230 * @return the hash value based on the string's collation order. 231 * @see UnicodeString#hashCode 232 * @stable ICU 2.0 233 */ 234 int32_t hashCode(void) const; 235 236 /** 237 * ICU "poor man's RTTI", returns a UClassID for the actual class. 238 * @stable ICU 2.2 239 */ 240 virtual UClassID getDynamicClassID() const override; 241 242 /** 243 * ICU "poor man's RTTI", returns a UClassID for this class. 244 * @stable ICU 2.2 245 */ 246 static UClassID U_EXPORT2 getStaticClassID(); 247 248 private: 249 /** 250 * Replaces the current bytes buffer with a new one of newCapacity 251 * and copies length bytes from the old buffer to the new one. 252 * @return the new buffer, or nullptr if the allocation failed 253 */ 254 uint8_t *reallocate(int32_t newCapacity, int32_t length); 255 /** 256 * Set a new length for a new sort key in the existing fBytes. 257 */ 258 void setLength(int32_t newLength); 259 260 uint8_t *getBytes() { 261 return (fFlagAndLength >= 0) ? fUnion.fStackBuffer : fUnion.fFields.fBytes; 262 } 263 const uint8_t *getBytes() const { 264 return (fFlagAndLength >= 0) ? fUnion.fStackBuffer : fUnion.fFields.fBytes; 265 } 266 int32_t getCapacity() const { 267 return (fFlagAndLength >= 0) ? (int32_t)sizeof(fUnion) : fUnion.fFields.fCapacity; 268 } 269 int32_t getLength() const { return fFlagAndLength & 0x7fffffff; } 270 271 /** 272 * Set the CollationKey to a "bogus" or invalid state 273 * @return this CollationKey 274 */ 275 CollationKey& setToBogus(void); 276 /** 277 * Resets this CollationKey to an empty state 278 * @return this CollationKey 279 */ 280 CollationKey& reset(void); 281 282 /** 283 * Allow private access to RuleBasedCollator 284 */ 285 friend class RuleBasedCollator; 286 friend class CollationKeyByteSink; 287 288 // Class fields. sizeof(CollationKey) is intended to be 48 bytes 289 // on a machine with 64-bit pointers. 290 // We use a union to maximize the size of the internal buffer, 291 // similar to UnicodeString but not as tight and complex. 292 293 // (implicit) *vtable; 294 /** 295 * Sort key length and flag. 296 * Bit 31 is set if the buffer is heap-allocated. 297 * Bits 30..0 contain the sort key length. 298 */ 299 int32_t fFlagAndLength; 300 /** 301 * Unique hash value of this CollationKey. 302 * Special value 2 if the key is bogus. 303 */ 304 mutable int32_t fHashCode; 305 /** 306 * fUnion provides 32 bytes for the internal buffer or for 307 * pointer+capacity. 308 */ 309 union StackBufferOrFields { 310 /** fStackBuffer is used iff fFlagAndLength>=0, else fFields is used */ 311 uint8_t fStackBuffer[32]; 312 struct { 313 uint8_t *fBytes; 314 int32_t fCapacity; 315 } fFields; 316 } fUnion; 317 }; 318 319 inline bool 320 CollationKey::operator!=(const CollationKey& other) const 321 { 322 return !(*this == other); 323 } 324 325 inline UBool 326 CollationKey::isBogus() const 327 { 328 return fHashCode == 2; // kBogusHashCode 329 } 330 331 inline const uint8_t* 332 CollationKey::getByteArray(int32_t &count) const 333 { 334 count = getLength(); 335 return getBytes(); 336 } 337 338 U_NAMESPACE_END 339 340 #endif /* #if !UCONFIG_NO_COLLATION */ 341 342 #endif /* U_SHOW_CPLUSPLUS_API */ 343 344 #endif
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