Re: Incorporating comments in syntax tree?

I just read a nice article on a tool called A* for language specific
tools. It is based on pattern matching and first-order tree
traversal. It has a nice method to handle comments, reminding me on a
b* tree with linear chaining of leaves:


- link all tokens in a linear list
- intertwine comments in this list in souce order
- compose non-terminals by pointers of the terminal tokens to elements of the
token list


Thus comments can be reached from normal tokens by previous/next-
operations, but not from non-terminals. Thus the grammar is not
complicated at all, but all comments can be reached starting from
terminal tokens. Example:


                      expr
                          |
                          -----------------------------------------
                          | | |
                          a <--> + <--> /* comment */ <--> b






@Article{ladd.95a,
    author = "Ladd, David A. and Ramming, J. Christopher",
    title = "A*: A Language for Implementing Language Processors",
    journal = "IEEE Transactions on Software Engineering",
    year = 1995,
    volume = 21,
    number = 11,
    pages = "894--901",
    month = "nov"
}




Can anyone comment on experiences with that?


--------------------------------------------------------------
Uwe Assmann
INRIA Rocquencourt, Bat. 13
Domaine de Voluceau BP 105
78153 Le Chesnay Cedex, France
email: Uwe.Assmann@inria.fr fax: +33/39 63 53 30 tel: +33/1/39 63 53 84
http://www-rocq.inria.fr/~assmann
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