1 // © 2016 and later: Unicode, Inc. and others.
2 // License & terms of use: http://www.unicode.org/copyright.html
3 /*
4 **************************************************************************
5 * Copyright (C) 1999-2012, International Business Machines Corporation and
6 * others. All Rights Reserved.
7 **************************************************************************
8 * Date Name Description
9 * 11/17/99 aliu Creation. Ported from java. Modified to
10 * match current UnicodeString API. Forced
11 * to use name "handleReplaceBetween" because
12 * of existing methods in UnicodeString.
13 **************************************************************************
14 */
15
16 #ifndef REP_H
17 #define REP_H
18
19 #include "unicode/uobject.h"
20
21 /**
22 * \file
23 * \brief C++ API: Replaceable String
24 */
25
26 U_NAMESPACE_BEGIN
27
28 class UnicodeString;
29
30 /**
31 * <code>Replaceable</code> is an abstract base class representing a
32 * string of characters that supports the replacement of a range of
33 * itself with a new string of characters. It is used by APIs that
34 * change a piece of text while retaining metadata. Metadata is data
35 * other than the Unicode characters returned by char32At(). One
36 * example of metadata is style attributes; another is an edit
37 * history, marking each character with an author and revision number.
38 *
39 * <p>An implicit aspect of the <code>Replaceable</code> API is that
40 * during a replace operation, new characters take on the metadata of
41 * the old characters. For example, if the string "the <b>bold</b>
42 * font" has range (4, 8) replaced with "strong", then it becomes "the
43 * <b>strong</b> font".
44 *
45 * <p><code>Replaceable</code> specifies ranges using a start
46 * offset and a limit offset. The range of characters thus specified
47 * includes the characters at offset start..limit-1. That is, the
48 * start offset is inclusive, and the limit offset is exclusive.
49 *
50 * <p><code>Replaceable</code> also includes API to access characters
51 * in the string: <code>length()</code>, <code>charAt()</code>,
52 * <code>char32At()</code>, and <code>extractBetween()</code>.
53 *
54 * <p>For a subclass to support metadata, typical behavior of
55 * <code>replace()</code> is the following:
56 * <ul>
57 * <li>Set the metadata of the new text to the metadata of the first
58 * character replaced</li>
59 * <li>If no characters are replaced, use the metadata of the
60 * previous character</li>
61 * <li>If there is no previous character (i.e. start == 0), use the
62 * following character</li>
63 * <li>If there is no following character (i.e. the replaceable was
64 * empty), use default metadata.<br>
65 * <li>If the code point U+FFFF is seen, it should be interpreted as
66 * a special marker having no metadata<li>
67 * </li>
68 * </ul>
69 * If this is not the behavior, the subclass should document any differences.
70 * @author Alan Liu
71 * @stable ICU 2.0
72 */
73 class U_COMMON_API Replaceable : public UObject {
74
75 public:
76 /**
77 * Destructor.
78 * @stable ICU 2.0
79 */
80 virtual ~Replaceable();
81
82 /**
83 * Returns the number of 16-bit code units in the text.
84 * @return number of 16-bit code units in text
85 * @stable ICU 1.8
86 */
87 inline int32_t length() const;
88
89 /**
90 * Returns the 16-bit code unit at the given offset into the text.
91 * @param offset an integer between 0 and <code>length()</code>-1
92 * inclusive
93 * @return 16-bit code unit of text at given offset
94 * @stable ICU 1.8
95 */
96 inline char16_t charAt(int32_t offset) const;
97
98 /**
99 * Returns the 32-bit code point at the given 16-bit offset into
100 * the text. This assumes the text is stored as 16-bit code units
101 * with surrogate pairs intermixed. If the offset of a leading or
102 * trailing code unit of a surrogate pair is given, return the
103 * code point of the surrogate pair.
104 *
105 * @param offset an integer between 0 and <code>length()</code>-1
106 * inclusive
107 * @return 32-bit code point of text at given offset
108 * @stable ICU 1.8
109 */
110 inline UChar32 char32At(int32_t offset) const;
111
112 /**
113 * Copies characters in the range [<tt>start</tt>, <tt>limit</tt>)
114 * into the UnicodeString <tt>target</tt>.
115 * @param start offset of first character which will be copied
116 * @param limit offset immediately following the last character to
117 * be copied
118 * @param target UnicodeString into which to copy characters.
119 * @return A reference to <TT>target</TT>
120 * @stable ICU 2.1
121 */
122 virtual void extractBetween(int32_t start,
123 int32_t limit,
124 UnicodeString& target) const = 0;
125
126 /**
127 * Replaces a substring of this object with the given text. If the
128 * characters being replaced have metadata, the new characters
129 * that replace them should be given the same metadata.
130 *
131 * <p>Subclasses must ensure that if the text between start and
132 * limit is equal to the replacement text, that replace has no
133 * effect. That is, any metadata
134 * should be unaffected. In addition, subclasses are encouraged to
135 * check for initial and trailing identical characters, and make a
136 * smaller replacement if possible. This will preserve as much
137 * metadata as possible.
138 * @param start the beginning index, inclusive; <code>0 <= start
139 * <= limit</code>.
140 * @param limit the ending index, exclusive; <code>start <= limit
141 * <= length()</code>.
142 * @param text the text to replace characters <code>start</code>
143 * to <code>limit - 1</code>
144 * @stable ICU 2.0
145 */
146 virtual void handleReplaceBetween(int32_t start,
147 int32_t limit,
148 const UnicodeString& text) = 0;
149 // Note: All other methods in this class take the names of
150 // existing UnicodeString methods. This method is the exception.
151 // It is named differently because all replace methods of
152 // UnicodeString return a UnicodeString&. The 'between' is
153 // required in order to conform to the UnicodeString naming
154 // convention; API taking start/length are named <operation>, and
155 // those taking start/limit are named <operationBetween>. The
156 // 'handle' is added because 'replaceBetween' and
157 // 'doReplaceBetween' are already taken.
158
159 /**
160 * Copies a substring of this object, retaining metadata.
161 * This method is used to duplicate or reorder substrings.
162 * The destination index must not overlap the source range.
163 *
164 * @param start the beginning index, inclusive; <code>0 <= start <=
165 * limit</code>.
166 * @param limit the ending index, exclusive; <code>start <= limit <=
167 * length()</code>.
168 * @param dest the destination index. The characters from
169 * <code>start..limit-1</code> will be copied to <code>dest</code>.
170 * Implementations of this method may assume that <code>dest <= start ||
171 * dest >= limit</code>.
172 * @stable ICU 2.0
173 */
174 virtual void copy(int32_t start, int32_t limit, int32_t dest) = 0;
175
176 /**
177 * Returns true if this object contains metadata. If a
178 * Replaceable object has metadata, calls to the Replaceable API
179 * must be made so as to preserve metadata. If it does not, calls
180 * to the Replaceable API may be optimized to improve performance.
181 * The default implementation returns true.
182 * @return true if this object contains metadata
183 * @stable ICU 2.2
184 */
185 virtual UBool hasMetaData() const;
186
187 /**
188 * Clone this object, an instance of a subclass of Replaceable.
189 * Clones can be used concurrently in multiple threads.
190 * If a subclass does not implement clone(), or if an error occurs,
191 * then NULL is returned.
192 * The clone functions in all subclasses return a pointer to a Replaceable
193 * because some compilers do not support covariant (same-as-this)
194 * return types; cast to the appropriate subclass if necessary.
195 * The caller must delete the clone.
196 *
197 * @return a clone of this object
198 *
199 * @see getDynamicClassID
200 * @stable ICU 2.6
201 */
202 virtual Replaceable *clone() const;
203
204 protected:
205
206 /**
207 * Default constructor.
208 * @stable ICU 2.4
209 */
210 inline Replaceable();
211
212 /*
213 * Assignment operator not declared. The compiler will provide one
214 * which does nothing since this class does not contain any data members.
215 * API/code coverage may show the assignment operator as present and
216 * untested - ignore.
217 * Subclasses need this assignment operator if they use compiler-provided
218 * assignment operators of their own. An alternative to not declaring one
219 * here would be to declare and empty-implement a protected or public one.
220 Replaceable &Replaceable::operator=(const Replaceable &);
221 */
222
223 /**
224 * Virtual version of length().
225 * @stable ICU 2.4
226 */
227 virtual int32_t getLength() const = 0;
228
229 /**
230 * Virtual version of charAt().
231 * @stable ICU 2.4
232 */
233 virtual char16_t getCharAt(int32_t offset) const = 0;
234
235 /**
236 * Virtual version of char32At().
237 * @stable ICU 2.4
238 */
239 virtual UChar32 getChar32At(int32_t offset) const = 0;
240 };
241
Replaceable()242 inline Replaceable::Replaceable() {}
243
244 inline int32_t
length()245 Replaceable::length() const {
246 return getLength();
247 }
248
249 inline char16_t
charAt(int32_t offset)250 Replaceable::charAt(int32_t offset) const {
251 return getCharAt(offset);
252 }
253
254 inline UChar32
char32At(int32_t offset)255 Replaceable::char32At(int32_t offset) const {
256 return getChar32At(offset);
257 }
258
259 // There is no rep.cpp, see unistr.cpp for Replaceable function implementations.
260
261 U_NAMESPACE_END
262
263 #endif
264