Re: Input buffer overflow in lex...

John R. Levine <johnl@iecc.cambridge.ma.us> writes:
> Well, the short answer is that you lose. No version of lex checks for
> token buffer overflow, although it is less destructive in flex than it is
> in lex. This can be called a lex design error, though it's hard to
> check for overflow without making the lexer a lot slower.


Let me clarify a bit. flex does detect token buffer overflow and
generates a fatal run-time error when it occurs. It can do so cheaply
because such overflow can only occur when new characters are being read
into the input buffer. That's a rare operation in a flex scanner because
input is block-oriented.


> The other possibility is to use start states to build the string
> yourself:


Hear hear! This is in general a much better approach, as it also provides
a natural way to deal with escape sequences and continued strings.


Vern


Vern Paxson vern@ee.lbl.gov
Systems Engineering ucbvax!ee.lbl.gov!vern
Lawrence Berkeley Laboratory (510) 486-7504
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