Replaceable
An implicit aspect of the Replaceable API is that * during a replace operation, new characters take on the metadata of * the old characters. For example, if the string "the bold * font" has range (4, 8) replaced with "strong", then it becomes "the * strong font". * *
Replaceable specifies ranges using a start * offset and a limit offset. The range of characters thus specified * includes the characters at offset start..limit-1. That is, the * start offset is inclusive, and the limit offset is exclusive. * *
Replaceable also includes API to access characters * in the string: length(), charAt(), * char32At(), and extractBetween(). * *
length()
charAt()
char32At()
extractBetween()
For a subclass to support metadata, typical behavior of * replace() is the following: *
replace()
Subclasses must ensure that if the text between start and * limit is equal to the replacement text, that replace has no * effect. That is, any metadata * should be unaffected. In addition, subclasses are encouraged to * check for initial and trailing identical characters, and make a * smaller replacement if possible. This will preserve as much * metadata as possible. * @param start the beginning index, inclusive; 0 <= start * <= limit. * @param limit the ending index, exclusive; start <= limit * <= length(). * @param text the text to replace characters start * to limit - 1 * @stable ICU 2.0 */ virtual void handleReplaceBetween(int32_t start, int32_t limit, const UnicodeString& text) = 0; // Note: All other methods in this class take the names of // existing UnicodeString methods. This method is the exception. // It is named differently because all replace methods of // UnicodeString return a UnicodeString&. The 'between' is // required in order to conform to the UnicodeString naming // convention; API taking start/length are named , and // those taking start/limit are named . The // 'handle' is added because 'replaceBetween' and // 'doReplaceBetween' are already taken. /** * Copies a substring of this object, retaining metadata. * This method is used to duplicate or reorder substrings. * The destination index must not overlap the source range. * * @param start the beginning index, inclusive; 0 <= start <= * limit. * @param limit the ending index, exclusive; start <= limit <= * length(). * @param dest the destination index. The characters from * start..limit-1 will be copied to dest. * Implementations of this method may assume that dest <= start || * dest >= limit. * @stable ICU 2.0 */ virtual void copy(int32_t start, int32_t limit, int32_t dest) = 0; /** * Returns true if this object contains metadata. If a * Replaceable object has metadata, calls to the Replaceable API * must be made so as to preserve metadata. If it does not, calls * to the Replaceable API may be optimized to improve performance. * The default implementation returns true. * @return true if this object contains metadata * @stable ICU 2.2 */ virtual UBool hasMetaData() const; /** * Clone this object, an instance of a subclass of Replaceable. * Clones can be used concurrently in multiple threads. * If a subclass does not implement clone(), or if an error occurs, * then NULL is returned. * The caller must delete the clone. * * @return a clone of this object * * @see getDynamicClassID * @stable ICU 2.6 */ virtual Replaceable *clone() const; protected: /** * Default constructor. * @stable ICU 2.4 */ inline Replaceable(); /* * Assignment operator not declared. The compiler will provide one * which does nothing since this class does not contain any data members. * API/code coverage may show the assignment operator as present and * untested - ignore. * Subclasses need this assignment operator if they use compiler-provided * assignment operators of their own. An alternative to not declaring one * here would be to declare and empty-implement a protected or public one. Replaceable &Replaceable::operator=(const Replaceable &); */ /** * Virtual version of length(). * @stable ICU 2.4 */ virtual int32_t getLength() const = 0; /** * Virtual version of charAt(). * @stable ICU 2.4 */ virtual char16_t getCharAt(int32_t offset) const = 0; /** * Virtual version of char32At(). * @stable ICU 2.4 */ virtual UChar32 getChar32At(int32_t offset) const = 0; }; inline Replaceable::Replaceable() {} inline int32_t Replaceable::length() const { return getLength(); } inline char16_t Replaceable::charAt(int32_t offset) const { return getCharAt(offset); } inline UChar32 Replaceable::char32At(int32_t offset) const { return getChar32At(offset); } // There is no rep.cpp, see unistr.cpp for Replaceable function implementations. U_NAMESPACE_END #endif /* U_SHOW_CPLUSPLUS_API */ #endif
0 <= start * <= limit
start <= limit * <= length()
start
limit - 1
0 <= start <= * limit
start <= limit <= * length()
start..limit-1
dest
dest <= start || * dest >= limit