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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*
6* Copyright (C) 2002-2012, International Business Machines
7* Corporation and others. All Rights Reserved.
8*
9*******************************************************************************
10*/
11
12#ifndef STRENUM_H
13#define STRENUM_H
14
15#include "unicode/uobject.h"
16#include "unicode/unistr.h"
17
18/**
19 * \file
20 * \brief C++ API: String Enumeration
21 */
22
23U_NAMESPACE_BEGIN
24
25/**
26 * Base class for 'pure' C++ implementations of uenum api. Adds a
27 * method that returns the next UnicodeString since in C++ this can
28 * be a common storage format for strings.
29 *
30 * <p>The model is that the enumeration is over strings maintained by
31 * a 'service.' At any point, the service might change, invalidating
32 * the enumerator (though this is expected to be rare). The iterator
33 * returns an error if this has occurred. Lack of the error is no
34 * guarantee that the service didn't change immediately after the
35 * call, so the returned string still might not be 'valid' on
36 * subsequent use.</p>
37 *
38 * <p>Strings may take the form of const char*, const char16_t*, or const
39 * UnicodeString*. The type you get is determine by the variant of
40 * 'next' that you call. In general the StringEnumeration is
41 * optimized for one of these types, but all StringEnumerations can
42 * return all types. Returned strings are each terminated with a NUL.
43 * Depending on the service data, they might also include embedded NUL
44 * characters, so API is provided to optionally return the true
45 * length, counting the embedded NULs but not counting the terminating
46 * NUL.</p>
47 *
48 * <p>The pointers returned by next, unext, and snext become invalid
49 * upon any subsequent call to the enumeration's destructor, next,
50 * unext, snext, or reset.</p>
51 *
52 * ICU 2.8 adds some default implementations and helper functions
53 * for subclasses.
54 *
55 * @stable ICU 2.4
56 */
57class U_COMMON_API StringEnumeration : public UObject {
58public:
59 /**
60 * Destructor.
61 * @stable ICU 2.4
62 */
63 virtual ~StringEnumeration();
64
65 /**
66 * Clone this object, an instance of a subclass of StringEnumeration.
67 * Clones can be used concurrently in multiple threads.
68 * If a subclass does not implement clone(), or if an error occurs,
69 * then NULL is returned.
70 * The clone functions in all subclasses return a base class pointer
71 * because some compilers do not support covariant (same-as-this)
72 * return types; cast to the appropriate subclass if necessary.
73 * The caller must delete the clone.
74 *
75 * @return a clone of this object
76 *
77 * @see getDynamicClassID
78 * @stable ICU 2.8
79 */
80 virtual StringEnumeration *clone() const;
81
82 /**
83 * <p>Return the number of elements that the iterator traverses. If
84 * the iterator is out of sync with its service, status is set to
85 * U_ENUM_OUT_OF_SYNC_ERROR, and the return value is zero.</p>
86 *
87 * <p>The return value will not change except possibly as a result of
88 * a subsequent call to reset, or if the iterator becomes out of sync.</p>
89 *
90 * <p>This is a convenience function. It can end up being very
91 * expensive as all the items might have to be pre-fetched
92 * (depending on the storage format of the data being
93 * traversed).</p>
94 *
95 * @param status the error code.
96 * @return number of elements in the iterator.
97 *
98 * @stable ICU 2.4 */
99 virtual int32_t count(UErrorCode& status) const = 0;
100
101 /**
102 * <p>Returns the next element as a NUL-terminated char*. If there
103 * are no more elements, returns NULL. If the resultLength pointer
104 * is not NULL, the length of the string (not counting the
105 * terminating NUL) is returned at that address. If an error
106 * status is returned, the value at resultLength is undefined.</p>
107 *
108 * <p>The returned pointer is owned by this iterator and must not be
109 * deleted by the caller. The pointer is valid until the next call
110 * to next, unext, snext, reset, or the enumerator's destructor.</p>
111 *
112 * <p>If the iterator is out of sync with its service, status is set
113 * to U_ENUM_OUT_OF_SYNC_ERROR and NULL is returned.</p>
114 *
115 * <p>If the native service string is a char16_t* string, it is
116 * converted to char* with the invariant converter. If the
117 * conversion fails (because a character cannot be converted) then
118 * status is set to U_INVARIANT_CONVERSION_ERROR and the return
119 * value is undefined (though not NULL).</p>
120 *
121 * Starting with ICU 2.8, the default implementation calls snext()
122 * and handles the conversion.
123 * Either next() or snext() must be implemented differently by a subclass.
124 *
125 * @param status the error code.
126 * @param resultLength a pointer to receive the length, can be NULL.
127 * @return a pointer to the string, or NULL.
128 *
129 * @stable ICU 2.4
130 */
131 virtual const char* next(int32_t *resultLength, UErrorCode& status);
132
133 /**
134 * <p>Returns the next element as a NUL-terminated char16_t*. If there
135 * are no more elements, returns NULL. If the resultLength pointer
136 * is not NULL, the length of the string (not counting the
137 * terminating NUL) is returned at that address. If an error
138 * status is returned, the value at resultLength is undefined.</p>
139 *
140 * <p>The returned pointer is owned by this iterator and must not be
141 * deleted by the caller. The pointer is valid until the next call
142 * to next, unext, snext, reset, or the enumerator's destructor.</p>
143 *
144 * <p>If the iterator is out of sync with its service, status is set
145 * to U_ENUM_OUT_OF_SYNC_ERROR and NULL is returned.</p>
146 *
147 * Starting with ICU 2.8, the default implementation calls snext()
148 * and handles the conversion.
149 *
150 * @param status the error code.
151 * @param resultLength a ponter to receive the length, can be NULL.
152 * @return a pointer to the string, or NULL.
153 *
154 * @stable ICU 2.4
155 */
156 virtual const char16_t* unext(int32_t *resultLength, UErrorCode& status);
157
158 /**
159 * <p>Returns the next element a UnicodeString*. If there are no
160 * more elements, returns NULL.</p>
161 *
162 * <p>The returned pointer is owned by this iterator and must not be
163 * deleted by the caller. The pointer is valid until the next call
164 * to next, unext, snext, reset, or the enumerator's destructor.</p>
165 *
166 * <p>If the iterator is out of sync with its service, status is set
167 * to U_ENUM_OUT_OF_SYNC_ERROR and NULL is returned.</p>
168 *
169 * Starting with ICU 2.8, the default implementation calls next()
170 * and handles the conversion.
171 * Either next() or snext() must be implemented differently by a subclass.
172 *
173 * @param status the error code.
174 * @return a pointer to the string, or NULL.
175 *
176 * @stable ICU 2.4
177 */
178 virtual const UnicodeString* snext(UErrorCode& status);
179
180 /**
181 * <p>Resets the iterator. This re-establishes sync with the
182 * service and rewinds the iterator to start at the first
183 * element.</p>
184 *
185 * <p>Previous pointers returned by next, unext, or snext become
186 * invalid, and the value returned by count might change.</p>
187 *
188 * @param status the error code.
189 *
190 * @stable ICU 2.4
191 */
192 virtual void reset(UErrorCode& status) = 0;
193
194 /**
195 * Compares this enumeration to other to check if both are equal
196 *
197 * @param that The other string enumeration to compare this object to
198 * @return TRUE if the enumerations are equal. FALSE if not.
199 * @stable ICU 3.6
200 */
201 virtual UBool operator==(const StringEnumeration& that)const;
202 /**
203 * Compares this enumeration to other to check if both are not equal
204 *
205 * @param that The other string enumeration to compare this object to
206 * @return TRUE if the enumerations are equal. FALSE if not.
207 * @stable ICU 3.6
208 */
209 virtual UBool operator!=(const StringEnumeration& that)const;
210
211protected:
212 /**
213 * UnicodeString field for use with default implementations and subclasses.
214 * @stable ICU 2.8
215 */
216 UnicodeString unistr;
217 /**
218 * char * default buffer for use with default implementations and subclasses.
219 * @stable ICU 2.8
220 */
221 char charsBuffer[32];
222 /**
223 * char * buffer for use with default implementations and subclasses.
224 * Allocated in constructor and in ensureCharsCapacity().
225 * @stable ICU 2.8
226 */
227 char *chars;
228 /**
229 * Capacity of chars, for use with default implementations and subclasses.
230 * @stable ICU 2.8
231 */
232 int32_t charsCapacity;
233
234 /**
235 * Default constructor for use with default implementations and subclasses.
236 * @stable ICU 2.8
237 */
238 StringEnumeration();
239
240 /**
241 * Ensures that chars is at least as large as the requested capacity.
242 * For use with default implementations and subclasses.
243 *
244 * @param capacity Requested capacity.
245 * @param status ICU in/out error code.
246 * @stable ICU 2.8
247 */
248 void ensureCharsCapacity(int32_t capacity, UErrorCode &status);
249
250 /**
251 * Converts s to Unicode and sets unistr to the result.
252 * For use with default implementations and subclasses,
253 * especially for implementations of snext() in terms of next().
254 * This is provided with a helper function instead of a default implementation
255 * of snext() to avoid potential infinite loops between next() and snext().
256 *
257 * For example:
258 * \code
259 * const UnicodeString* snext(UErrorCode& status) {
260 * int32_t resultLength=0;
261 * const char *s=next(&resultLength, status);
262 * return setChars(s, resultLength, status);
263 * }
264 * \endcode
265 *
266 * @param s String to be converted to Unicode.
267 * @param length Length of the string.
268 * @param status ICU in/out error code.
269 * @return A pointer to unistr.
270 * @stable ICU 2.8
271 */
272 UnicodeString *setChars(const char *s, int32_t length, UErrorCode &status);
273};
274
275U_NAMESPACE_END
276
277/* STRENUM_H */
278#endif
279

Warning: That file was not part of the compilation database. It may have many parsing errors.