Re: Problem with GIF file scanner (flex)

Kristian Nilssen <kxn@dcs.ed.ac.uk> wrote:
> For some
> unknown reason, flex will not enter the Logical_Screen_Descriptor
> ...
> %%
> %{
> BEGIN Header;
> %}


By putting the "BEGIN Header" as indented code at the beginning of the
rules, it's executed every time you call yylex. Since the rule used
to enter Logical_Screen_Descriptor ends with a return statement,
you're for sure reexecuting "BEGIN Header" before scanning the next
token, so you lose the Logical_Screen_Descriptor state and instead
wind up in "Header" again.


Either get rid of the return in the <Header> rule, or get rid of <Header>
entirely, along with the "BEGIN Header". With %x, you don't need to worry
about any conflicts between Header and Logical_Screen_Descriptor, anyway,
so there's no pressing need to have the header scanning be it's own start
condition.


                                Vern
[Oh. right. Oops. -John]


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