Replaceable Class Reference

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>

Inheritance diagram for Replaceable:
UObject UMemory UnicodeString

Public Member Functions

virtual ~Replaceable ()
 Destructor.
int32_t length () const
 Returns the number of 16-bit code units in the text.
UChar charAt (int32_t offset) const
 Returns the 16-bit code unit at the given offset into the text.
UChar32 char32At (int32_t offset) const
 Returns the 32-bit code point at the given 16-bit offset into the text.
virtual void extractBetween (int32_t start, int32_t limit, UnicodeString &target) const =0
 Copies characters in the range [start, limit) into the UnicodeString target.
virtual void handleReplaceBetween (int32_t start, int32_t limit, const UnicodeString &text)=0
 Replaces a substring of this object with the given text.
virtual void copy (int32_t start, int32_t limit, int32_t dest)=0
 Copies a substring of this object, retaining metadata.
virtual UBool hasMetaData () const
 Returns true if this object contains metadata.
virtual Replaceableclone () const
 Clone this object, an instance of a subclass of Replaceable.

Protected Member Functions

 Replaceable ()
 Default constructor.
virtual int32_t getLength () const =0
 Virtual version of length().
virtual UChar getCharAt (int32_t offset) const =0
 Virtual version of charAt().
virtual UChar32 getChar32At (int32_t offset) const =0
 Virtual version of char32At().

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 by char32At(). 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 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 <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(), and extractBetween().

For a subclass to support metadata, typical behavior of replace() is the following:

If this is not the behavior, the subclass should document any differences.

Author:
Alan Liu
Stable:
ICU 2.0

Definition at line 71 of file rep.h.


Constructor & Destructor Documentation

virtual Replaceable::~Replaceable (  )  [virtual]

Destructor.

Stable:
ICU 2.0
Replaceable::Replaceable (  )  [protected]

Default constructor.

Stable:
ICU 2.4

Member Function Documentation

UChar32 Replaceable::char32At ( int32_t  offset  )  const [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

Reimplemented in UnicodeString.

Definition at line 251 of file rep.h.

References getChar32At().

UChar Replaceable::charAt ( int32_t  offset  )  const [inline]

Returns the 16-bit code unit at the given offset into the text.

Parameters:
offset an integer between 0 and length()-1 inclusive
Returns:
16-bit code unit of text at given offset
Stable:
ICU 1.8

Reimplemented in UnicodeString.

Definition at line 246 of file rep.h.

References getCharAt().

virtual Replaceable* Replaceable::clone (  )  const [virtual]

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 clone functions in all subclasses return a pointer to a Replaceable because some compilers do not support covariant (same-as-this) return types; cast to the appropriate subclass if necessary. The caller must delete the clone.

Returns:
a clone of this object
See also:
getDynamicClassID
Stable:
ICU 2.6

Reimplemented in UnicodeString.

virtual void Replaceable::copy ( int32_t  start,
int32_t  limit,
int32_t  dest 
) [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-1 will be copied to dest. Implementations of this method may assume that dest <= start || dest >= limit.
Stable:
ICU 2.0

Implemented in UnicodeString.

virtual void Replaceable::extractBetween ( int32_t  start,
int32_t  limit,
UnicodeString target 
) const [pure virtual]

Copies characters in the range [start, limit) into the UnicodeString target.

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
virtual UChar32 Replaceable::getChar32At ( int32_t  offset  )  const [protected, pure virtual]

Virtual version of char32At().

Stable:
ICU 2.4

Implemented in UnicodeString.

Referenced by char32At().

virtual UChar Replaceable::getCharAt ( int32_t  offset  )  const [protected, pure virtual]

Virtual version of charAt().

Stable:
ICU 2.4

Implemented in UnicodeString.

Referenced by charAt().

virtual int32_t Replaceable::getLength (  )  const [protected, pure virtual]

Virtual version of length().

Stable:
ICU 2.4

Implemented in UnicodeString.

Referenced by length().

virtual void Replaceable::handleReplaceBetween ( int32_t  start,
int32_t  limit,
const UnicodeString text 
) [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 start to limit - 1
Stable:
ICU 2.0
virtual UBool Replaceable::hasMetaData (  )  const [virtual]

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.

Returns:
true if this object contains metadata
Stable:
ICU 2.2

Reimplemented in UnicodeString.

int32_t Replaceable::length ( void   )  const [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

Reimplemented in UnicodeString.

Definition at line 241 of file rep.h.

References getLength().


The documentation for this class was generated from the following file:
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Generated on Sat Jan 23 15:17:43 2010 for ICU 4.3.4 by  doxygen 1.6.1