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$Revision: 1.2 $ $Author: death $ $Date: 93/04/04 23:45:24 $ TextConverter INHERITS FROM ResultObject DECLARED IN TextConverter.h CLASS DESCRIPTION The TextConverter class serves as a base class for new classes. It provides little functionality on its own. Classes decended from TextConverter will convert text from one character set to another. For instance, a subclass might convert text from a Macintosh file to equivalent text for a NeXT application. The TextConverter class, itself, merely takes Characters, and returns them to the caller unaltered. There are two primarly methods provided by TextConverter, and they should be overridden by all subclasses. ConvertCharacter: takes a single character, and returns an equivalent character in the destination character set (e.g. if it is passed a Mac 0xA5 (bullet) character, it might return the character 0xB7 (a bullet in the NeXT character set)). If the character can not be mapped to a single character, then the subclass is free to choose whether to leave the value unchanged, or make an approximation. The second method, ConvertString:WithLength: also converts from one character set to another. Unlike ConvertCharacter:, it allows for converting a single character to multiple (e.g. a greater than or equal sign in one character set might be mapped to the pair of characters `>='). This class does not have specialized init or free methods. The inherited ones work adequately. Note that this class is essentially just a pair of functions bundled up as a fancy class! =) INSTANCE VARIABLES Declared in TextConverter none METHOD TYPES Converting characters - ConvertCharacter: - ConvertString:WithLength: CLASS METHODS None INSTANCE METHODS ConvertCharacter: - (Character) ConvertCharacter: (Character) theCharacter 0 Result codes and test 1 The returned character This returns a single character in the destination character set that most closely matches the character value that it is provided. In this TextConverter class, this method merely returns the value it was passed. ConvertString:WithLength: - (Pointer) ConvertString: (Pointer) theData WithLength: (Integer) length 0 Result codes and test 1 The returned Pointer 2 The lenght of the returning data This method takes a pointer to a string of length characters (length should be a character count, not a byte count, should the two ever be different). Like ConvertCharacter:, this will convert characters in the source data, which are assumed to be in one character set, into characters in its destination character set. The TextConverter class merely maps each incomming character to an identical outgoing character. There are two things to note in particular about this method. This method allows for mapping multiple source characters to single destination characters, or single source to multiple destination characters. Because of this, it can not directly modify the source string. Consequently, it always allocates a new block of memory, and converts into it. A pointer to this new block is returned, along with the length of the converted data. This data can later be deallocated with FreePointer(). BUGS AND PROBLEMS none yet ENHANCEMENT IDEAS none CONSTANT, DEFINED TYPES AND ERROR CODES #define errCANTMAPTOONE 1001 /* set by ConvertChar: if mapping would be > 1 dest char */ #define errCANTMAPFROMONE 1002 /* set by ConvertChar: if mapping needs > 1 source char */ MODIFICATION HISTORY $Log: TextConverter.rtf,v $Revision 1.2 93/04/04 23:45:24 deathSun Apr 4 23:45:23 PDT 1993 Revision 1.1 93/01/10 15:08:53 deathSun Jan 10 15:08:53 PST 1993 fi-20li3120
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.