[XeTeX] STFangsong punctuation kerning

[Likai Liu]

Hello,

I'm using STFangsong to typeset a Chinese document. This font provides 
full-width ideograph punctuation marks, which is necessary to maintain 
the grid looking of a well-printed Chinese document. However, if two 
full-width punctuation marks appear right next to each other, which 
often happens in a sentence with quotation marks or parentheses, there 
is a lot of redundant space. The solution is to "merge" two punctuation 
marks into one block.

But how to do this?

My current method is to make some of these punctuation characters 
"active" and make them a macro. The macro would lookahead using 
\futurelet and see how it wants to kern with the next character. This 
works well with a small set of punctuation marks, but as the list 
grows, I'm not able to maintain a scalable solution with my limited TeX 
knowledge.

(How do you maintain a "list" in TeX and use conditional to see if a 
given token is within the list?)

I heard some gossip on this mailing list about implementing overriding 
kerning pairs. Maybe this is really what I need. Any suggestions?

liulk