Re: is lex useful?

Scott.Nicol@infoadvan.com (Scott Nicol) writes:


s> - No support for wide (>8 bit) character sets. Even 8-bit support is
s> fairly recent. The obvious implementation for wide characters
s> (expand tables to 16 bits) isn't practical, because you would
s> increase the tables sizes (which are already huge) 256x.


Dennis Ritchie (I think) wrote a paper on wide-character regular
expression matching a few years ago; it used to be included in the
papers that came with Plan 9, but I haven't seen an online copy in
several years.


As far as I can remember, the solution he used for Plan 9 involved
building sparse tables. This is a fairly obvious thing to do, and the
extra indirection used to provide sparseness imposes some performance
penalty, but it saves gobs of space.


<b


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