Re: ICU4C Proposal: Add missing uset.h functions

George Rhoten wrote:
> There are some C++ UnicodeSet functions that are missing from the uset_* C 
> API.  I propose that some missing functions be added.  This proposal is 
> for jitterbug 3341.

This will be really good to have.

A couple of comments -

 > /**
 >  * Implementation of UnicodeMatcher API.  Union the set of all
 >  * characters that may be matched by this object into the given
 >  * set.
 >  * @param set the source used to generate the union
 >  * @param toUnionTo the set into which to union the source characters
 >  * @draft ICU 3.2
 >  */
 > U_DRAFT void U_EXPORT2
 > uset_addMatchSetTo(const USet* set, USet* toUnionTo);

I don't think that we need this function.  It does the same thing as the 
already existing uset_addAll(), and exists as a separate function in the 
  C++ UnicodeSet class only because that class is implementing the 
UnicodeMatcher interface.

The class hierarchy was probably a mistake - it ties UnicodeSet too much 
to transliterators, while UnicodeSet is a more general concept.  At any 
rate, there's no need to propagate this into the C API.

-------

 > /**
 >  * Return true if the given position, in the given pattern, appears
 >  * to be the start of a UnicodeSet pattern.
 >  *
 >  * @param set the object to be tested for the given pattern and position
 >  * @param pattern a string specifying the pattern
 >  * @param patternLength the length of the pattern, or -1 if NULL
 >  * @param pos the given position
 >  * @draft ICU 3.2
 >  */
 > U_DRAFT UBool U_EXPORT2
 > uset_resemblesPattern(const USet* set,
 >                       const UChar *pattern, int32_t patternLength,
 >                       int32_t pos);

The first parameter, "set" shouldn't be there.  (In C++, it's a static 
function).

I'm not so sure that the function should have been included at all, but 
I guess since it's there in C++ that we should include it in the the C 
side for completeness.  All it does is check whether the first character 
being pointed to is a '['.

----

The following functions are available in the C++ UnicodeSet class, but 
not from C  (including the new proposal)

	clone()
	hashCode()               <--  Good to have
	ContainsAll(), ContainsNone(), ContainsSome()  variants that
             take  check against a range or a string.
             (The functions checking a against a USet are present)
	addAll(string s);
	retainAll(String s);
	complementAll(String);
	complement(Range)
	complement(string);
	removeAll(String);
	createFrom(String);
	createFromAll(String);
	closeOver(attribute)       <-- important for case folding
         compact()                  <--  Good to have

	getRangeCount()            <-- I'd prefer not to include these.
         getRangeStart()            <--  They expose too much
         getRangeEnd()              <--   implementation.


If the goal is to reproduce the C++ UnicodeSet functionality in the C 
API, probably at least some of these functions should be added as well.

Omitting overloaded functions that take a UChar32 code point parameter 
when a variant that takes a range already exists seems reasonable - the 
impact on user code is very small.

Omitting variants that take ranges or strings has a bigger impact.  The 
work around involves either loops or temporary objects in the client 
code.  But I'm not sure whether they are used much.

-- 
   -- Andy Heninger
      [email protected]