intl/icu/source/common/unicode/strenum.h@6474c204b198
intl/icu/source/common/unicode/strenum.h
Wed, 31 Dec 2014 06:09:35 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Wed, 31 Dec 2014 06:09:35 +0100
- changeset 0
- 6474c204b198
- permissions
- -rw-r--r--
Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.
1 /*
2 *******************************************************************************
3 *
4 * Copyright (C) 2002-2012, International Business Machines
5 * Corporation and others. All Rights Reserved.
6 *
7 *******************************************************************************
8 */
10 #ifndef STRENUM_H
11 #define STRENUM_H
13 #include "unicode/uobject.h"
14 #include "unicode/unistr.h"
16 /**
17 * \file
18 * \brief C++ API: String Enumeration
19 */
21 U_NAMESPACE_BEGIN
23 /**
24 * Base class for 'pure' C++ implementations of uenum api. Adds a
25 * method that returns the next UnicodeString since in C++ this can
26 * be a common storage format for strings.
27 *
28 * <p>The model is that the enumeration is over strings maintained by
29 * a 'service.' At any point, the service might change, invalidating
30 * the enumerator (though this is expected to be rare). The iterator
31 * returns an error if this has occurred. Lack of the error is no
32 * guarantee that the service didn't change immediately after the
33 * call, so the returned string still might not be 'valid' on
34 * subsequent use.</p>
35 *
36 * <p>Strings may take the form of const char*, const UChar*, or const
37 * UnicodeString*. The type you get is determine by the variant of
38 * 'next' that you call. In general the StringEnumeration is
39 * optimized for one of these types, but all StringEnumerations can
40 * return all types. Returned strings are each terminated with a NUL.
41 * Depending on the service data, they might also include embedded NUL
42 * characters, so API is provided to optionally return the true
43 * length, counting the embedded NULs but not counting the terminating
44 * NUL.</p>
45 *
46 * <p>The pointers returned by next, unext, and snext become invalid
47 * upon any subsequent call to the enumeration's destructor, next,
48 * unext, snext, or reset.</p>
49 *
50 * ICU 2.8 adds some default implementations and helper functions
51 * for subclasses.
52 *
53 * @stable ICU 2.4
54 */
55 class U_COMMON_API StringEnumeration : public UObject {
56 public:
57 /**
58 * Destructor.
59 * @stable ICU 2.4
60 */
61 virtual ~StringEnumeration();
63 /**
64 * Clone this object, an instance of a subclass of StringEnumeration.
65 * Clones can be used concurrently in multiple threads.
66 * If a subclass does not implement clone(), or if an error occurs,
67 * then NULL is returned.
68 * The clone functions in all subclasses return a base class pointer
69 * because some compilers do not support covariant (same-as-this)
70 * return types; cast to the appropriate subclass if necessary.
71 * The caller must delete the clone.
72 *
73 * @return a clone of this object
74 *
75 * @see getDynamicClassID
76 * @stable ICU 2.8
77 */
78 virtual StringEnumeration *clone() const;
80 /**
81 * <p>Return the number of elements that the iterator traverses. If
82 * the iterator is out of sync with its service, status is set to
83 * U_ENUM_OUT_OF_SYNC_ERROR, and the return value is zero.</p>
84 *
85 * <p>The return value will not change except possibly as a result of
86 * a subsequent call to reset, or if the iterator becomes out of sync.</p>
87 *
88 * <p>This is a convenience function. It can end up being very
89 * expensive as all the items might have to be pre-fetched
90 * (depending on the storage format of the data being
91 * traversed).</p>
92 *
93 * @param status the error code.
94 * @return number of elements in the iterator.
95 *
96 * @stable ICU 2.4 */
97 virtual int32_t count(UErrorCode& status) const = 0;
99 /**
100 * <p>Returns the next element as a NUL-terminated char*. If there
101 * are no more elements, returns NULL. If the resultLength pointer
102 * is not NULL, the length of the string (not counting the
103 * terminating NUL) is returned at that address. If an error
104 * status is returned, the value at resultLength is undefined.</p>
105 *
106 * <p>The returned pointer is owned by this iterator and must not be
107 * deleted by the caller. The pointer is valid until the next call
108 * to next, unext, snext, reset, or the enumerator's destructor.</p>
109 *
110 * <p>If the iterator is out of sync with its service, status is set
111 * to U_ENUM_OUT_OF_SYNC_ERROR and NULL is returned.</p>
112 *
113 * <p>If the native service string is a UChar* string, it is
114 * converted to char* with the invariant converter. If the
115 * conversion fails (because a character cannot be converted) then
116 * status is set to U_INVARIANT_CONVERSION_ERROR and the return
117 * value is undefined (though not NULL).</p>
118 *
119 * Starting with ICU 2.8, the default implementation calls snext()
120 * and handles the conversion.
121 * Either next() or snext() must be implemented differently by a subclass.
122 *
123 * @param status the error code.
124 * @param resultLength a pointer to receive the length, can be NULL.
125 * @return a pointer to the string, or NULL.
126 *
127 * @stable ICU 2.4
128 */
129 virtual const char* next(int32_t *resultLength, UErrorCode& status);
131 /**
132 * <p>Returns the next element as a NUL-terminated UChar*. If there
133 * are no more elements, returns NULL. If the resultLength pointer
134 * is not NULL, the length of the string (not counting the
135 * terminating NUL) is returned at that address. If an error
136 * status is returned, the value at resultLength is undefined.</p>
137 *
138 * <p>The returned pointer is owned by this iterator and must not be
139 * deleted by the caller. The pointer is valid until the next call
140 * to next, unext, snext, reset, or the enumerator's destructor.</p>
141 *
142 * <p>If the iterator is out of sync with its service, status is set
143 * to U_ENUM_OUT_OF_SYNC_ERROR and NULL is returned.</p>
144 *
145 * Starting with ICU 2.8, the default implementation calls snext()
146 * and handles the conversion.
147 *
148 * @param status the error code.
149 * @param resultLength a ponter to receive the length, can be NULL.
150 * @return a pointer to the string, or NULL.
151 *
152 * @stable ICU 2.4
153 */
154 virtual const UChar* unext(int32_t *resultLength, UErrorCode& status);
156 /**
157 * <p>Returns the next element a UnicodeString*. If there are no
158 * more elements, returns NULL.</p>
159 *
160 * <p>The returned pointer is owned by this iterator and must not be
161 * deleted by the caller. The pointer is valid until the next call
162 * to next, unext, snext, reset, or the enumerator's destructor.</p>
163 *
164 * <p>If the iterator is out of sync with its service, status is set
165 * to U_ENUM_OUT_OF_SYNC_ERROR and NULL is returned.</p>
166 *
167 * Starting with ICU 2.8, the default implementation calls next()
168 * and handles the conversion.
169 * Either next() or snext() must be implemented differently by a subclass.
170 *
171 * @param status the error code.
172 * @return a pointer to the string, or NULL.
173 *
174 * @stable ICU 2.4
175 */
176 virtual const UnicodeString* snext(UErrorCode& status);
178 /**
179 * <p>Resets the iterator. This re-establishes sync with the
180 * service and rewinds the iterator to start at the first
181 * element.</p>
182 *
183 * <p>Previous pointers returned by next, unext, or snext become
184 * invalid, and the value returned by count might change.</p>
185 *
186 * @param status the error code.
187 *
188 * @stable ICU 2.4
189 */
190 virtual void reset(UErrorCode& status) = 0;
192 /**
193 * Compares this enumeration to other to check if both are equal
194 *
195 * @param that The other string enumeration to compare this object to
196 * @return TRUE if the enumerations are equal. FALSE if not.
197 * @stable ICU 3.6
198 */
199 virtual UBool operator==(const StringEnumeration& that)const;
200 /**
201 * Compares this enumeration to other to check if both are not equal
202 *
203 * @param that The other string enumeration to compare this object to
204 * @return TRUE if the enumerations are equal. FALSE if not.
205 * @stable ICU 3.6
206 */
207 virtual UBool operator!=(const StringEnumeration& that)const;
209 protected:
210 /**
211 * UnicodeString field for use with default implementations and subclasses.
212 * @stable ICU 2.8
213 */
214 UnicodeString unistr;
215 /**
216 * char * default buffer for use with default implementations and subclasses.
217 * @stable ICU 2.8
218 */
219 char charsBuffer[32];
220 /**
221 * char * buffer for use with default implementations and subclasses.
222 * Allocated in constructor and in ensureCharsCapacity().
223 * @stable ICU 2.8
224 */
225 char *chars;
226 /**
227 * Capacity of chars, for use with default implementations and subclasses.
228 * @stable ICU 2.8
229 */
230 int32_t charsCapacity;
232 /**
233 * Default constructor for use with default implementations and subclasses.
234 * @stable ICU 2.8
235 */
236 StringEnumeration();
238 /**
239 * Ensures that chars is at least as large as the requested capacity.
240 * For use with default implementations and subclasses.
241 *
242 * @param capacity Requested capacity.
243 * @param status ICU in/out error code.
244 * @stable ICU 2.8
245 */
246 void ensureCharsCapacity(int32_t capacity, UErrorCode &status);
248 /**
249 * Converts s to Unicode and sets unistr to the result.
250 * For use with default implementations and subclasses,
251 * especially for implementations of snext() in terms of next().
252 * This is provided with a helper function instead of a default implementation
253 * of snext() to avoid potential infinite loops between next() and snext().
254 *
255 * For example:
256 * \code
257 * const UnicodeString* snext(UErrorCode& status) {
258 * int32_t resultLength=0;
259 * const char *s=next(&resultLength, status);
260 * return setChars(s, resultLength, status);
261 * }
262 * \endcode
263 *
264 * @param s String to be converted to Unicode.
265 * @param length Length of the string.
266 * @param status ICU in/out error code.
267 * @return A pointer to unistr.
268 * @stable ICU 2.8
269 */
270 UnicodeString *setChars(const char *s, int32_t length, UErrorCode &status);
271 };
273 U_NAMESPACE_END
275 /* STRENUM_H */
276 #endif
