Martin Mares <m...@ucw.cz> wrote on 2010/04/29 17:57:44:
>
> Hello!
>
> > Right, neither is an ideal fix but at least mine is "correct" and doesn't
> > cause REJECT to be defined inside flex, causing warnings.
> >
> > I don't understand your reasoning, you rather keep the buggy REJECT
> > instead of renaming the bison token REJECT to Reject because it
> > doesn't look as "pretty" anymore?
>
> Why exactly do you consider the REJECT buggy? Does the documentation of flex
> forbid redefinition of REJECT?
>From info flex:
There are a number of special directives which can be included
within an action:
`ECHO'
copies yytext to the scanner's output.
`BEGIN'
followed by the name of a start condition places the scanner in the
corresponding start condition (see below).
`REJECT'
directs the scanner to proceed on to the "second best" rule which
matched the input (or a prefix of the input). The rule is chosen
as described above in *Note Matching::, and `yytext' and `yyleng'
set up appropriately. It may either be one which matched as much
text as the originally chosen rule but came later in the `flex'
input file, or one which matched less text. For example, the
following will both count the words in the input and call the
routine `special()' whenever `frob' is seen:
int word_count = 0;
%%
frob special(); REJECT;
[^ \t\n]+ ++word_count;
Without the `REJECT', any occurrences of `frob' in the input would
not be counted as words, since the scanner normally executes only
one action per token. Multiple uses of `REJECT' are allowed, each
one finding the next best choice to the currently active rule. For
example, when the following scanner scans the token `abcd', it will
write `abcdabcaba' to the output:
....
`flex' scans your rule actions to determine whether you use the
`REJECT' or `yymore()' features. The `REJECT' and `yymore' options are
available to override its decision as to whether you use the options,
either by setting them (e.g., `%option reject)' to indicate the feature
is indeed used, or unsetting them to indicate it actually is not used
(e.g., `%option noyymore)'.
Another indication is:
flex -s -Cf -B -8 -ocf-lex.c -Pcf_ cf-lex.l
flex: REJECT cannot be used with -f or -F
make: *** [cf-lex.c] Error 1
You can't use -Cf because flex think you are using REJECT in your
scanner.
>
> Sure, it is not elegant and it might cause bugs in the future (currently, I do
> not see any real bug), but your rename is not elegant either.
No, but it is the equivalent of renaming a variable from an ideal name
to a less ideal name, not a big deal.
