Re: Forcing multiple parse stacks to 'reduce'
Hans,
>>typedef x y;
>>typedef i j;
>>{
>>
>>is a syntactically valid function definition.
>
>So it seems, but I have not been able to figure out which function. :-)
The syntax does not permit an empty declaration. So x must
be the declarator. The second typedef is simply a declaration
and is not necessary for this to be a syntactically correct
function definition. It's presence simply increases to the
amazement factor.
> The
>problem is that C has some grammar difficulties.
The C declaration grammar was designed to mimic
the syntax of how the declarator would appear in an
expression. Irrespective of whether this is a good idea
in itself, the resulting declaration syntax is not people
friendly.
My current problem is (courtesy of the last documentation
update) a reported ambiguity in:
static foo (bar);
static int foo (lose);
Both declarations parse ok when they are the only line in a
file. Putting both lines together gives a surprising ambiguity
report.
>I have some vague memory that somebody found (fairly late, in the 90'ies) a
>grammar transformation to make C becoming LALR(1) (modulo the usual context
>tweaks for "typedef", etc.) Then you would not need using the %glr option.
>You might check the newsgroup comp.compilers and its FAQ, published there
>monthly.
I have a lalr(1) grammar for C (who doesn't?). The first edition
of Harbison&Steele list the output from such a tool for C.
My interest is in measuring visible source (see
www.knosof.co.uk/cbook/usefigtab.pdf ; skip to
table 26; the source of many of the tools can be found
at: www.knosof.co.uk/cbook/srccnt.tgz ) and using a
grammar that is as close as possible to that given in the
C Standard has many advantages. Performance is not
an issue (not that I think that nondeterministic parsing would
be a performance bottleneck).
derek
--
Derek M Jones tel: +44 (0) 1252 520
667
Knowledge Software Ltdmailto:[EMAIL PROTECTED]
Applications Standards Conformance Testing http://www.knosof.co.uk
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Re: Identifying rule responsible for lookahead
Please keep the cc to help-bison so that others may help. On 2005/03/02 00:38, Soumitra Kumar at [EMAIL PROTECTED] wrote: > Thanks for your comment. > I thought there may be a way to get this information > from --trace option, that's why I posted on help-bison > list. The question is how. > I have read the LALR(1) and bison algorithm (I forgot > the author's name). I was wondering if there is any > design document of bison. Actually I had tried to hack > bison code to print it, but could not. If there any > documentation it would help. No, there is no such Bison design doc's: Only reading the Bison source code itself. (Apart from that somebody wrote something in Spanish, I think.) > -Soumitra. > >> >> The problem is how to extract the information from >> the LALR(1) algorithm, if >> possible. Do you have any suggestion? (I may think a >> bit more on the >> question.) >> >> It is otherwise not a help-bison issue, but a >> "featuritis" issue, which >> normally should be posted in the bug-bison list. >> >> Hans Aberg > > > > __ > Do you Yahoo!? > Yahoo! Mail - Find what you need with new enhanced search. > http://info.mail.yahoo.com/mail_250 ___ Help-bison@gnu.org http://lists.gnu.org/mailman/listinfo/help-bison
Re: Forcing multiple parse stacks to 'reduce'
On 2005/03/02 17:07, Derek M Jones at [EMAIL PROTECTED] wrote: >> I have some vague memory that somebody found (fairly late, in the 90'ies) a >> grammar transformation to make C becoming LALR(1) (modulo the usual context >> tweaks for "typedef", etc.) Then you would not need using the %glr option. >> You might check the newsgroup comp.compilers and its FAQ, published there >> monthly. > > I have a lalr(1) grammar for C (who doesn't?). The first edition > of Harbison&Steele list the output from such a tool for C. There is nothing such in my Harbison&Steele (4th ed.). The comment I recall was that I think it was Paul Hilfinger who asked Bjarne Stroustrup (in cmop.compilers) why certain C++ ambiguities where in that language, and the latter replied it had to do with the fact that they had not a C LALR(1) grammar at the time the designed those C++ features. But my memory could be wrong. Hans Aberg ___ Help-bison@gnu.org http://lists.gnu.org/mailman/listinfo/help-bison
Re: Identifying rule responsible for lookahead
On Wednesday 02 March 2005 19.50, Hans Aberg wrote: > Please keep the cc to help-bison so that others may help. could you restate your problem ? ___ Help-bison@gnu.org http://lists.gnu.org/mailman/listinfo/help-bison
Re: Identifying rule responsible for lookahead
For the grammar: %token YYID YYDOT %% identifier : hier_id ; hier_id : simple_id | hier_id opt_select YYDOT simple_id ; opt_select : | opt_select '[' expr ']' ; simple_id : YYID ; expr : hier_id | function_call ; function_call : expr YYDOT YYID ; Is it possible to get following output from bison? state 10 3 hier_id: hier_id . opt_select YYDOT simple_id 4 opt_select: . [YYDOT (3), '[' (5)] ^^^ ^^^ 5 | . opt_select '[' expr ']' 7 expr: hier_id . [YYDOT (9), ']' (5)] ^^^ ^^^ YYDOT reduce using rule 4 (opt_select) YYDOT [reduce using rule 7 (expr)] i.e. annotate the rule which is responsible for any lookahead symbol. -Soumitra. --- Henrik Sorensen <[EMAIL PROTECTED]> wrote: > On Wednesday 02 March 2005 19.50, Hans Aberg wrote: > > Please keep the cc to help-bison so that others > may help. > could you restate your problem ? > __ Celebrate Yahoo!'s 10th Birthday! Yahoo! Netrospective: 100 Moments of the Web http://birthday.yahoo.com/netrospective/ ___ Help-bison@gnu.org http://lists.gnu.org/mailman/listinfo/help-bison
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Re: bison install
Plantier, Spencer wrote: I have installed m4-1.4 and made sure the path is in my path statement. When I install bison I get the following error: checking for gnum4... no checking for m4... /usr/ccs/bin/m4 checking whether m4 supports frozen files... no configure: error: GNU M4 1.4 is required Any help would be appreciated. try m4 --version if you don't have 1.4, then you need to download and install it. Alfonso. ___ Help-bison@gnu.org http://lists.gnu.org/mailman/listinfo/help-bison
