Replaceable is an abstract base class representing a string of characters that supports the replacement of a range of itself with a new string of characters.More...
#include <rep.h>
Public Member Functions | |
| virtual | ~Replaceable () |
| Destructor.More... | |
| int32_t | length () const |
| Returns the number of 16-bit code units in the text.More... | |
| char16_t | charAt (int32_t offset) const |
| Returns the 16-bit code unit at the given offset into the text.More... | |
| UChar32 | char32At (int32_t offset) const |
| Returns the 32-bit code point at the given 16-bit offset into the text.More... | |
| virtual void | extractBetween (int32_t start, int32_t limit,UnicodeString &target) const =0 |
Copies characters in the range [start,limit) into theUnicodeStringtarget.More... | |
| virtual void | handleReplaceBetween (int32_t start, int32_t limit, constUnicodeString &text)=0 |
| Replaces a substring of this object with the given text.More... | |
| virtual void | copy (int32_t start, int32_t limit, int32_t dest)=0 |
| Copies a substring of this object, retaining metadata.More... | |
| virtualUBool | hasMetaData () const |
| Returns true if this object contains metadata.More... | |
| virtualReplaceable * | clone () const |
| Clone this object, an instance of a subclass ofReplaceable.More... | |
 Public Member Functions inherited fromicu::UObject | |
| virtual | ~UObject () |
| Destructor.More... | |
| virtualUClassID | getDynamicClassID () const |
| ICU4C "poor man's RTTI", returns a UClassID for the actual ICU class.More... | |
Protected Member Functions | |
| Replaceable () | |
| Default constructor.More... | |
| virtual int32_t | getLength () const =0 |
| Virtual version oflength().More... | |
| virtual char16_t | getCharAt (int32_t offset) const =0 |
| Virtual version ofcharAt().More... | |
| virtualUChar32 | getChar32At (int32_t offset) const =0 |
| Virtual version ofchar32At().More... | |
Detailed Description
Replaceable is an abstract base class representing a string of characters that supports the replacement of a range of itself with a new string of characters.
It is used by APIs that change a piece of text while retaining metadata. Metadata is data other than the Unicode characters returned bychar32At(). One example of metadata is style attributes; another is an edit history, marking each character with an author and revision number.
An implicit aspect of theReplaceable API is that during a replace operation, new characters take on the metadata of the old characters. For example, if the string "the <b>bold</b>font" has range (4, 8) replaced with "strong", then it becomes "the<b>strong</b> 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(), andextractBetween().
For a subclass to support metadata, typical behavior ofreplace() is the following:
- Set the metadata of the new text to the metadata of the first character replaced
- If no characters are replaced, use the metadata of the previous character
- If there is no previous character (i.e. start == 0), use the following character
- If there is no following character (i.e. the replaceable was empty), use default metadata.
- If the code point U+FFFF is seen, it should be interpreted as a special marker having no metadata
If this is not the behavior, the subclass should document any differences.
- Author
- Alan Liu
- Stable:
- ICU 2.0
Constructor & Destructor Documentation
◆ ~Replaceable()
| virtual |
Destructor.
- Stable:
- ICU 2.0
◆ Replaceable()
| inlineprotected |
Member Function Documentation
◆ char32At()
| inline |
Returns the 32-bit code point at the given 16-bit offset into the text.
This assumes the text is stored as 16-bit code units with surrogate pairs intermixed. If the offset of a leading or trailing code unit of a surrogate pair is given, return the code point of the surrogate pair.
- Parameters
offset an integer between 0 and length()-1 inclusive
- Returns
- 32-bit code point of text at given offset
- Stable:
- ICU 1.8
◆ charAt()
| inline |
◆ clone()
| virtual |
Clone this object, an instance of a subclass ofReplaceable.
Clones can be used concurrently in multiple threads. If a subclass does not implementclone(), or if an error occurs, then nullptr is returned. The caller must delete the clone.
- Returns
- a clone of this object
- See also
- getDynamicClassID
- Stable:
- ICU 2.6
Reimplemented inicu::UnicodeString.
◆ copy()
| pure virtual |
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.
- Parameters
start the beginning index, inclusive; 0 <= start <= limit.limit the ending index, exclusive; start <= limit <=length().dest the destination index. The characters from start..limit-1will be copied todest. Implementations of this method may assume thatdest <= start || dest >= limit.
- Stable:
- ICU 2.0
Implemented inicu::UnicodeString.
◆ extractBetween()
| pure virtual |
Copies characters in the range [start,limit) into theUnicodeStringtarget.
- Parameters
start offset of first character which will be copied limit offset immediately following the last character to be copied target UnicodeString into which to copy characters.
- Returns
- A reference to
target
- Stable:
- ICU 2.1
Implemented inicu::UnicodeString.
◆ getChar32At()
| protectedpure virtual |
◆ getCharAt()
| protectedpure virtual |
◆ getLength()
| protectedpure virtual |
◆ handleReplaceBetween()
| pure virtual |
Replaces a substring of this object with the given text.
If the characters being replaced have metadata, the new characters that replace them should be given the same metadata.
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.
- Parameters
start the beginning index, inclusive; 0 <= start <= limit.limit the ending index, exclusive; start <= limit <=length().text the text to replace characters starttolimit - 1
- Stable:
- ICU 2.0
Implemented inicu::UnicodeString.
◆ hasMetaData()
| virtual |
Returns true if this object contains metadata.
If aReplaceable object has metadata, calls to theReplaceable API must be made so as to preserve metadata. If it does not, calls to theReplaceable API may be optimized to improve performance. The default implementation returns true.
- Returns
- true if this object contains metadata
- Stable:
- ICU 2.2
Reimplemented inicu::UnicodeString.
◆ length()
| inline |
Returns the number of 16-bit code units in the text.
- Returns
- number of 16-bit code units in text
- Stable:
- ICU 1.8
Definition at line246 of filerep.h.
Referenced byicu::UnicodeString::operator std::u16string_view(),icu::UnicodeString::operator std::wstring_view(),icu::UnicodeString::operator=(),icu::UnicodeString::operator==(), andicu::UnicodeString::toUTF8String().
The documentation for this class was generated from the following file:
- common/unicode/rep.h
