aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/libs/icu/include/unicode/appendable.h
blob: 0e37f4562a58390f8d7553b2d019c6edea5ee026 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
*******************************************************************************
*   Copyright (C) 2011-2012, International Business Machines
*   Corporation and others.  All Rights Reserved.
*******************************************************************************
*   file name:  appendable.h
*   encoding:   UTF-8
*   tab size:   8 (not used)
*   indentation:4
*
*   created on: 2010dec07
*   created by: Markus W. Scherer
*/

#ifndef __APPENDABLE_H__
#define __APPENDABLE_H__

/**
 * \file
 * \brief C++ API: Appendable class: Sink for Unicode code points and 16-bit code units (char16_ts).
 */

#include "unicode/utypes.h"

#if U_SHOW_CPLUSPLUS_API

#include "unicode/uobject.h"

U_NAMESPACE_BEGIN

class UnicodeString;

/**
 * Base class for objects to which Unicode characters and strings can be appended.
 * Combines elements of Java Appendable and ICU4C ByteSink.
 *
 * This class can be used in APIs where it does not matter whether the actual destination is
 * a UnicodeString, a char16_t[] array, a UnicodeSet, or any other object
 * that receives and processes characters and/or strings.
 *
 * Implementation classes must implement at least appendCodeUnit(char16_t).
 * The base class provides default implementations for the other methods.
 *
 * The methods do not take UErrorCode parameters.
 * If an error occurs (e.g., out-of-memory),
 * in addition to returning false from failing operations,
 * the implementation must prevent unexpected behavior (e.g., crashes)
 * from further calls and should make the error condition available separately
 * (e.g., store a UErrorCode, make/keep a UnicodeString bogus).
 * @stable ICU 4.8
 */
class U_COMMON_API Appendable : public UObject {
public:
    /**
     * Destructor.
     * @stable ICU 4.8
     */
    ~Appendable();

    /**
     * Appends a 16-bit code unit.
     * @param c code unit
     * @return true if the operation succeeded
     * @stable ICU 4.8
     */
    virtual UBool appendCodeUnit(char16_t c) = 0;

    /**
     * Appends a code point.
     * The default implementation calls appendCodeUnit(char16_t) once or twice.
     * @param c code point 0..0x10ffff
     * @return true if the operation succeeded
     * @stable ICU 4.8
     */
    virtual UBool appendCodePoint(UChar32 c);

    /**
     * Appends a string.
     * The default implementation calls appendCodeUnit(char16_t) for each code unit.
     * @param s string, must not be nullptr if length!=0
     * @param length string length, or -1 if NUL-terminated
     * @return true if the operation succeeded
     * @stable ICU 4.8
     */
    virtual UBool appendString(const char16_t *s, int32_t length);

    /**
     * Tells the object that the caller is going to append roughly
     * appendCapacity char16_ts. A subclass might use this to pre-allocate
     * a larger buffer if necessary.
     * The default implementation does nothing. (It always returns true.)
     * @param appendCapacity estimated number of char16_ts that will be appended
     * @return true if the operation succeeded
     * @stable ICU 4.8
     */
    virtual UBool reserveAppendCapacity(int32_t appendCapacity);

    /**
     * Returns a writable buffer for appending and writes the buffer's capacity to
     * *resultCapacity. Guarantees *resultCapacity>=minCapacity.
     * May return a pointer to the caller-owned scratch buffer which must have
     * scratchCapacity>=minCapacity.
     * The returned buffer is only valid until the next operation
     * on this Appendable.
     *
     * After writing at most *resultCapacity char16_ts, call appendString() with the
     * pointer returned from this function and the number of char16_ts written.
     * Many appendString() implementations will avoid copying char16_ts if this function
     * returned an internal buffer.
     *
     * Partial usage example:
     * \code
     *  int32_t capacity;
     *  char16_t* buffer = app.getAppendBuffer(..., &capacity);
     *  ... Write n char16_ts into buffer, with n <= capacity.
     *  app.appendString(buffer, n);
     * \endcode
     * In many implementations, that call to append will avoid copying char16_ts.
     *
     * If the Appendable allocates or reallocates an internal buffer, it should use
     * the desiredCapacityHint if appropriate.
     * If a caller cannot provide a reasonable guess at the desired capacity,
     * it should pass desiredCapacityHint=0.
     *
     * If a non-scratch buffer is returned, the caller may only pass
     * a prefix to it to appendString().
     * That is, it is not correct to pass an interior pointer to appendString().
     *
     * The default implementation always returns the scratch buffer.
     *
     * @param minCapacity required minimum capacity of the returned buffer;
     *                    must be non-negative
     * @param desiredCapacityHint desired capacity of the returned buffer;
     *                            must be non-negative
     * @param scratch default caller-owned buffer
     * @param scratchCapacity capacity of the scratch buffer
     * @param resultCapacity pointer to an integer which will be set to the
     *                       capacity of the returned buffer
     * @return a buffer with *resultCapacity>=minCapacity
     * @stable ICU 4.8
     */
    virtual char16_t *getAppendBuffer(int32_t minCapacity,
                                   int32_t desiredCapacityHint,
                                   char16_t *scratch, int32_t scratchCapacity,
                                   int32_t *resultCapacity);
};

/**
 * An Appendable implementation which writes to a UnicodeString.
 *
 * This class is not intended for public subclassing.
 * @stable ICU 4.8
 */
class U_COMMON_API UnicodeStringAppendable : public Appendable {
public:
    /**
     * Aliases the UnicodeString (keeps its reference) for writing.
     * @param s The UnicodeString to which this Appendable will write.
     * @stable ICU 4.8
     */
    explicit UnicodeStringAppendable(UnicodeString &s) : str(s) {}

    /**
     * Destructor.
     * @stable ICU 4.8
     */
    ~UnicodeStringAppendable();

    /**
     * Appends a 16-bit code unit to the string.
     * @param c code unit
     * @return true if the operation succeeded
     * @stable ICU 4.8
     */
    virtual UBool appendCodeUnit(char16_t c) override;

    /**
     * Appends a code point to the string.
     * @param c code point 0..0x10ffff
     * @return true if the operation succeeded
     * @stable ICU 4.8
     */
    virtual UBool appendCodePoint(UChar32 c) override;

    /**
     * Appends a string to the UnicodeString.
     * @param s string, must not be nullptr if length!=0
     * @param length string length, or -1 if NUL-terminated
     * @return true if the operation succeeded
     * @stable ICU 4.8
     */
    virtual UBool appendString(const char16_t *s, int32_t length) override;

    /**
     * Tells the UnicodeString that the caller is going to append roughly
     * appendCapacity char16_ts.
     * @param appendCapacity estimated number of char16_ts that will be appended
     * @return true if the operation succeeded
     * @stable ICU 4.8
     */
    virtual UBool reserveAppendCapacity(int32_t appendCapacity) override;

    /**
     * Returns a writable buffer for appending and writes the buffer's capacity to
     * *resultCapacity. Guarantees *resultCapacity>=minCapacity.
     * May return a pointer to the caller-owned scratch buffer which must have
     * scratchCapacity>=minCapacity.
     * The returned buffer is only valid until the next write operation
     * on the UnicodeString.
     *
     * For details see Appendable::getAppendBuffer().
     *
     * @param minCapacity required minimum capacity of the returned buffer;
     *                    must be non-negative
     * @param desiredCapacityHint desired capacity of the returned buffer;
     *                            must be non-negative
     * @param scratch default caller-owned buffer
     * @param scratchCapacity capacity of the scratch buffer
     * @param resultCapacity pointer to an integer which will be set to the
     *                       capacity of the returned buffer
     * @return a buffer with *resultCapacity>=minCapacity
     * @stable ICU 4.8
     */
    virtual char16_t *getAppendBuffer(int32_t minCapacity,
                                   int32_t desiredCapacityHint,
                                   char16_t *scratch, int32_t scratchCapacity,
                                   int32_t *resultCapacity) override;

private:
    UnicodeString &str;
};

U_NAMESPACE_END

#endif /* U_SHOW_CPLUSPLUS_API */

#endif  // __APPENDABLE_H__