1 /* 2 ************************************************************************** 3 * Copyright (C) 1999-2005, International Business Machines Corporation and 4 * others. All Rights Reserved. 5 ************************************************************************** 6 * Date Name Description 7 * 11/17/99 aliu Creation. Ported from java. Modified to 8 * match current UnicodeString API. Forced 9 * to use name "handleReplaceBetween" because 10 * of existing methods in UnicodeString. 11 ************************************************************************** 12 */ 13 14 #ifndef REP_H 15 #define REP_H 16 17 #include "unicode/uobject.h" 18 19 /** 20 * \file 21 * \brief C++ API: Replaceable String 22 */ 23 24 U_NAMESPACE_BEGIN 25 26 class UnicodeString; 27 28 /** 29 * <code>Replaceable</code> is an abstract base class representing a 30 * string of characters that supports the replacement of a range of 31 * itself with a new string of characters. It is used by APIs that 32 * change a piece of text while retaining metadata. Metadata is data 33 * other than the Unicode characters returned by char32At(). One 34 * example of metadata is style attributes; another is an edit 35 * history, marking each character with an author and revision number. 36 * 37 * <p>An implicit aspect of the <code>Replaceable</code> API is that 38 * during a replace operation, new characters take on the metadata of 39 * the old characters. For example, if the string "the <b>bold</b> 40 * font" has range (4, 8) replaced with "strong", then it becomes "the 41 * <b>strong</b> font". 42 * 43 * <p><code>Replaceable</code> specifies ranges using a start 44 * offset and a limit offset. The range of characters thus specified 45 * includes the characters at offset start..limit-1. That is, the 46 * start offset is inclusive, and the limit offset is exclusive. 47 * 48 * <p><code>Replaceable</code> also includes API to access characters 49 * in the string: <code>length()</code>, <code>charAt()</code>, 50 * <code>char32At()</code>, and <code>extractBetween()</code>. 51 * 52 * <p>For a subclass to support metadata, typical behavior of 53 * <code>replace()</code> is the following: 54 * <ul> 55 * <li>Set the metadata of the new text to the metadata of the first 56 * character replaced</li> 57 * <li>If no characters are replaced, use the metadata of the 58 * previous character</li> 59 * <li>If there is no previous character (i.e. start == 0), use the 60 * following character</li> 61 * <li>If there is no following character (i.e. the replaceable was 62 * empty), use default metadata.<br> 63 * <li>If the code point U+FFFF is seen, it should be interpreted as 64 * a special marker having no metadata<li> 65 * </li> 66 * </ul> 67 * If this is not the behavior, the subclass should document any differences. 68 * @author Alan Liu 69 * @stable ICU 2.0 70 */ 71 class U_COMMON_API Replaceable : public UObject { 72 73 public: 74 /** 75 * Destructor. 76 * @stable ICU 2.0 77 */ 78 virtual ~Replaceable(); 79 80 /** 81 * Returns the number of 16-bit code units in the text. 82 * @return number of 16-bit code units in text 83 * @stable ICU 1.8 84 */ 85 inline int32_t length() const; 86 87 /** 88 * Returns the 16-bit code unit at the given offset into the text. 89 * @param offset an integer between 0 and <code>length()</code>-1 90 * inclusive 91 * @return 16-bit code unit of text at given offset 92 * @stable ICU 1.8 93 */ 94 inline UChar charAt(int32_t offset) const; 95 96 /** 97 * Returns the 32-bit code point at the given 16-bit offset into 98 * the text. This assumes the text is stored as 16-bit code units 99 * with surrogate pairs intermixed. If the offset of a leading or 100 * trailing code unit of a surrogate pair is given, return the 101 * code point of the surrogate pair. 102 * 103 * @param offset an integer between 0 and <code>length()</code>-1 104 * inclusive 105 * @return 32-bit code point of text at given offset 106 * @stable ICU 1.8 107 */ 108 inline UChar32 char32At(int32_t offset) const; 109 110 /** 111 * Copies characters in the range [<tt>start</tt>, <tt>limit</tt>) 112 * into the UnicodeString <tt>target</tt>. 113 * @param start offset of first character which will be copied 114 * @param limit offset immediately following the last character to 115 * be copied 116 * @param target UnicodeString into which to copy characters. 117 * @return A reference to <TT>target</TT> 118 * @stable ICU 2.1 119 */ 120 virtual void extractBetween(int32_t start, 121 int32_t limit, 122 UnicodeString& target) const = 0; 123 124 /** 125 * Replaces a substring of this object with the given text. If the 126 * characters being replaced have metadata, the new characters 127 * that replace them should be given the same metadata. 128 * 129 * <p>Subclasses must ensure that if the text between start and 130 * limit is equal to the replacement text, that replace has no 131 * effect. That is, any metadata 132 * should be unaffected. In addition, subclasses are encouraged to 133 * check for initial and trailing identical characters, and make a 134 * smaller replacement if possible. This will preserve as much 135 * metadata as possible. 136 * @param start the beginning index, inclusive; <code>0 <= start 137 * <= limit</code>. 138 * @param limit the ending index, exclusive; <code>start <= limit 139 * <= length()</code>. 140 * @param text the text to replace characters <code>start</code> 141 * to <code>limit - 1</code> 142 * @stable ICU 2.0 143 */ 144 virtual void handleReplaceBetween(int32_t start, 145 int32_t limit, 146 const UnicodeString& text) = 0; 147 // Note: All other methods in this class take the names of 148 // existing UnicodeString methods. This method is the exception. 149 // It is named differently because all replace methods of 150 // UnicodeString return a UnicodeString&. The 'between' is 151 // required in order to conform to the UnicodeString naming 152 // convention; API taking start/length are named <operation>, and 153 // those taking start/limit are named <operationBetween>. The 154 // 'handle' is added because 'replaceBetween' and 155 // 'doReplaceBetween' are already taken. 156 157 /** 158 * Copies a substring of this object, retaining metadata. 159 * This method is used to duplicate or reorder substrings. 160 * The destination index must not overlap the source range. 161 * 162 * @param start the beginning index, inclusive; <code>0 <= start <= 163 * limit</code>. 164 * @param limit the ending index, exclusive; <code>start <= limit <= 165 * length()</code>. 166 * @param dest the destination index. The characters from 167 * <code>start..limit-1</code> will be copied to <code>dest</code>. 168 * Implementations of this method may assume that <code>dest <= start || 169 * dest >= limit</code>. 170 * @stable ICU 2.0 171 */ 172 virtual void copy(int32_t start, int32_t limit, int32_t dest) = 0; 173 174 /** 175 * Returns true if this object contains metadata. If a 176 * Replaceable object has metadata, calls to the Replaceable API 177 * must be made so as to preserve metadata. If it does not, calls 178 * to the Replaceable API may be optimized to improve performance. 179 * The default implementation returns true. 180 * @return true if this object contains metadata 181 * @stable ICU 2.2 182 */ 183 virtual UBool hasMetaData() const; 184 185 /** 186 * Clone this object, an instance of a subclass of Replaceable. 187 * Clones can be used concurrently in multiple threads. 188 * If a subclass does not implement clone(), or if an error occurs, 189 * then NULL is returned. 190 * The clone functions in all subclasses return a pointer to a Replaceable 191 * because some compilers do not support covariant (same-as-this) 192 * return types; cast to the appropriate subclass if necessary. 193 * The caller must delete the clone. 194 * 195 * @return a clone of this object 196 * 197 * @see getDynamicClassID 198 * @stable ICU 2.6 199 */ 200 virtual Replaceable *clone() const; 201 202 protected: 203 204 /** 205 * Default constructor. 206 * @stable ICU 2.4 207 */ 208 Replaceable(); 209 210 /* 211 * Assignment operator not declared. The compiler will provide one 212 * which does nothing since this class does not contain any data members. 213 * API/code coverage may show the assignment operator as present and 214 * untested - ignore. 215 * Subclasses need this assignment operator if they use compiler-provided 216 * assignment operators of their own. An alternative to not declaring one 217 * here would be to declare and empty-implement a protected or public one. 218 Replaceable &Replaceable::operator=(const Replaceable &); 219 */ 220 221 /** 222 * Virtual version of length(). 223 * @stable ICU 2.4 224 */ 225 virtual int32_t getLength() const = 0; 226 227 /** 228 * Virtual version of charAt(). 229 * @stable ICU 2.4 230 */ 231 virtual UChar getCharAt(int32_t offset) const = 0; 232 233 /** 234 * Virtual version of char32At(). 235 * @stable ICU 2.4 236 */ 237 virtual UChar32 getChar32At(int32_t offset) const = 0; 238 }; 239 240 inline int32_t 241 Replaceable::length() const { 242 return getLength(); 243 } 244 245 inline UChar 246 Replaceable::charAt(int32_t offset) const { 247 return getCharAt(offset); 248 } 249 250 inline UChar32 251 Replaceable::char32At(int32_t offset) const { 252 return getChar32At(offset); 253 } 254 255 // There is no rep.cpp, see unistr.cpp for Replaceable function implementations. 256 257 U_NAMESPACE_END 258 259 #endif 260
