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