X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/d115aad9112fb4e2fe1b268c9db7390732d39539..d42e695e53bf9521593f074a58dd8165336df204:/TODO diff --git a/TODO b/TODO index 588bf468..e8509e3c 100644 --- a/TODO +++ b/TODO @@ -1,34 +1,60 @@ --*- outline -*- - * Short term -** Use syntax_error from the scanner? -This would provide a means to raise syntax error from function called -from the scanner. Actually, there is no good solution to report a -lexical error in general. Usually they are kept at the scanner level -only, ignoring the guilty token. But that might not be the best bet, -since we don't benefit from the syntactic error recovery. - -We still have the possibility to return an invalid token number, which -does the trick. But then the error message from the parser is poor -(something like "unexpected $undefined"). Since the scanner probably -already reported the error, we should directly enter error-recovery, -without reporting the error message (i.e., YYERROR's semantics). - -Back to lalr1.cc (whose name is now quite unfortunate, since it also -covers lr and ielr), if we support exceptions from yylex, should we -propose a lexical_error in addition to syntax_error? Should they have -a common root, say parse_error? Should syntax_error be renamed -syntactic_error for consistency with lexical_error? +** Graphviz display code thoughts +The code for the --graph option is over two files: print_graph, and +graphviz. I believe this is because Bison used to also produce VCG graphs, +but since this is no longer true, maybe we could consider these files for +fusion. + +Little effort factoring seems to have been given to factoring in these files, +and their print-xml and print counterpart. We would very much like to re-use +the pretty format of states from .output in the .dot + +Also, the underscore in print_graph.[ch] isn't very fitting considering +the dashes in the other filenames. + +** push-parser +Check it too when checking the different kinds of parsers. And be +sure to check that the initial-action is performed once per parsing. + +** m4 names +b4_shared_declarations is no longer what it is. Make it +b4_parser_declaration for instance. + +** yychar in lalr1.cc +There is a large difference bw maint and master on the handling of +yychar (which was removed in lalr1.cc). See what needs to be +back-ported. + + + /* User semantic actions sometimes alter yychar, and that requires + that yytoken be updated with the new translation. We take the + approach of translating immediately before every use of yytoken. + One alternative is translating here after every semantic action, + but that translation would be missed if the semantic action + invokes YYABORT, YYACCEPT, or YYERROR immediately after altering + yychar. In the case of YYABORT or YYACCEPT, an incorrect + destructor might then be invoked immediately. In the case of + YYERROR, subsequent parser actions might lead to an incorrect + destructor call or verbose syntax error message before the + lookahead is translated. */ + + /* Make sure we have latest lookahead translation. See comments at + user semantic actions for why this is necessary. */ + yytoken = yytranslate_ (yychar); + + +** $ and others in epilogue +A stray $ is a warning in the actions, but an error in the epilogue. +IMHO, it should not even be a warning in the epilogue. + +** stack.hh +Get rid of it. The original idea is nice, but actually it makes +the code harder to follow, and uselessly different from the other +skeletons. ** Variable names. What should we name `variant' and `lex_symbol'? -** Use b4_symbol in all the skeleton -Then remove the older system, including the tables generated by -output.c - -** Update the documentation on gnu.org - ** Get rid of fake #lines [Bison: ...] Possibly as simple as checking whether the column number is nonnegative. @@ -58,18 +84,7 @@ as lr0.cc, why upper case? ** bench several bisons. Enhance bench.pl with %b to run different bisons. -** Use b4_symbol everywhere. -Move its definition in the more standard places and deploy it in other -skeletons. - * Various -** YYPRINT -glr.c inherits its symbol_print function from c.m4, which supports -YYPRINT. But to use YYPRINT yytoknum is needed, which not defined by -glr.c. - -Anyway, IMHO YYPRINT is obsolete and should be restricted to yacc.c. - ** YYERRCODE Defined to 256, but not used, not documented. Probably the token number for the error token, which POSIX wants to be 256, but which @@ -115,9 +130,6 @@ so both 256 and 257 are "mysterious". "\"end of command\"", "error", "$undefined", "\"=\"", "\"break\"", -** YYFAIL -It is seems to be *really* obsolete now, shall we remove it? - ** yychar == yyempty_ The code in yyerrlab reads: @@ -152,23 +164,6 @@ we do the same in yacc.c. The code bw glr.c and yacc.c is really alike, we can certainly factor some parts. -* Header guards - -From Franc,ois: should we keep the directory part in the CPP guard? - - -* Yacc.c: CPP Macros - -Do some people use YYPURE, YYLSP_NEEDED like we do in the test suite? -They should not: it is not documented. But if they need to, let's -find something clean (not like YYLSP_NEEDED...). - - -* Installation - -* Documentation -Before releasing, make sure the documentation ("Understanding your -parser") refers to the current `output' format. * Report @@ -266,12 +261,6 @@ this issue. Does anybody have it? Some history of Bison and some bibliography would be most welcome. Are there any Texinfo standards for bibliography? -** %printer -Wow, %printer is not documented. Clearly mark YYPRINT as obsolete. - -* Java, Fortran, etc. - - * Coding system independence Paul notes: @@ -297,29 +286,6 @@ Show reductions. ** Skeleton strategy Must we keep %token-table? -* BTYacc -See if we can integrate backtracking in Bison. Charles-Henri de -Boysson has been working on this, but never gave -the results. - -Vadim Maslow, the maintainer of BTYacc was once contacted. Adjusting -the Bison grammar parser will be needed to support some extra BTYacc -features. This is less urgent. - -** Keeping the conflicted actions -First, analyze the differences between byacc and btyacc (I'm referring -to the executables). Find where the conflicts are preserved. - -** Compare with the GLR tables -See how isomorphic the way BTYacc and the way the GLR adjustments in -Bison are compatible. *As much as possible* one should try to use the -same implementation in the Bison executables. I insist: it should be -very feasible to use the very same conflict tables. - -** Adjust the skeletons -Import the skeletons for C and C++. - - * Precedence ** Partial order @@ -403,6 +369,12 @@ Here's a proposal for how a new implementation might look: http://lists.gnu.org/archive/html/bison-patches/2009-09/msg00086.html + +Local Variables: +mode: outline +coding: utf-8 +End: + ----- Copyright (C) 2001-2004, 2006, 2008-2012 Free Software Foundation, Inc.