Re: Lex and Yacc - Availability?

Vern Paxson <>
Wed, 19 Aug 87 22:31:37 PDT

          From comp.compilers

Related articles
Lex and Yacc - Availability? cullvax!drw@EDDIE.MIT.EDU (1987-08-12)
Re: Lex and Yacc - Availability? harvard!seismo!elsie!ncifcrf!randy (1987-08-17)
Re: Lex and Yacc - Availability? (Vern Paxson) (1987-08-19)
| List of all articles for this month |

Date: Wed, 19 Aug 87 22:31:37 PDT
From: Vern Paxson <>

> At the Winter 1987 Usenix Van Jacobson of LBL labs presented a
> paper describing a much improved version of Lex...
> processing down to a single table lookup in memory! (The rumor was
> that it was just marginally slower than 'cat'). I don't know what the
> current status of the project is; I would very much like either a copy
> of his paper or the program itself. Anyone know more than I?

A student I'm supervising is adding Van's fast algorithm to my lex
re-write ("flex"). He's finished with the basics of the implementation,
but there's still a lot of tuning and clean-up before it'll be ready
for a beta-test and subsequent release. (Details on distribution terms
are still being worked out, but it looks like it'll have a copyright that
says "freely redistribute, but don't make a significant enhancement
without contacting us first, and be willing to give UC rights to the
enhancement"; possibly it'll carry a more generous, GNU-like copyright.)

While there's still tuning to do, the preliminary results, done for a
C tokenizer, are (1) fast as cat? No, not quite (I'll be going over
the implementation with Van to see where tuning might be needed); (2) fast
as a hand-coded scanner? Well, as things stand now, it is about 15%
faster than PCC's tokenizer, which seems to have been done with some care.

Vern Paxson
Real Time Systems ucbvax!!vern
Lawrence Berkeley Laboratory (415) 486-6411

Post a followup to this message

Return to the comp.compilers page.
Search the comp.compilers archives again.