X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/67218723a0d9f663bfd4bcce25839f7141d6344e..1dce289a0070373300f399b2230c0dbdf366e729:/TODO diff --git a/TODO b/TODO index 24af226c..d2e457c9 100644 --- a/TODO +++ b/TODO @@ -1,13 +1,86 @@ * Short term -** Variable names. -What should we name `variant' and `lex_symbol'? - -** Use b4_symbol in all the skeleton -Move its definition in the more standard places and deploy it in other -skeletons. Then remove the older system, including the tables -generated by output.c - -** Update the documentation on gnu.org +** Laxism in Bison invocation arguments: +The flag_argmatch functions were meant to be generic. The introduction of +-Werror= in generic code is a bit troublesome, and generates weird +behaviour. Because seeing "error=" causes Bison to match the subsequent +categories with a generic procedure, but on a very specific variable, the +following commands are legal, and equivalent: + +$ bison -Werror=yacc # OK +$ bison --warnings=error=yacc # err, looks very weird? +$ bison -rerror=itemsets # this value of 'report' enum has a value + # of '1 << 1', just like Wyacc +$ bison --report=error=itemsets # (same) +$ bison -ferror=caret # (same) +$ bison --feature=error=caret # (same) + +Basically, writing -rerror={THINGS} or -ferror={FEATURE} is not prohibited, +and results in UB. + +I don't think there is any reason for the user to expect anything out of +these options (this implementation-driven behavior is not documented of +course, as it isn't exactly a feature), so this bug isn't critical but +should be addressed some day nonetheless. + +** Graphviz display code thoughts +The code for the --graph option is over two files: print_graph, and +graphviz. 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. + +An other consideration worth noting is that print_graph.c (correct me if I +am wrong) should contain generic functions, whereas graphviz.c and other +potential files should contain just the specific code for that output +format. It will probably prove difficult to tell if the implementation is +actually generic whilst only having support for a single format, but it +would be nice to keep stuff a bit tidier: right now, the construction of the +bitset used to show reductions is in the graphviz-specific code, and on the +opposite side we have some use of \l, which is graphviz-specific, in what +should be generic code. + +Little effort seems to have been given to factoring these files and their +rint{,-xml} counterpart. We would very much like to re-use the pretty format +of states from .output for the graphs, etc. + +Also, the underscore in print_graph.[ch] isn't very fitting considering the +dashes in the other filenames. + +Since graphviz dies on medium-to-big grammars, maybe consider an other tool? + +** 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); + + +** 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. ** Get rid of fake #lines [Bison: ...] Possibly as simple as checking whether the column number is nonnegative. @@ -35,21 +108,7 @@ since it is no longer bound to a particular parser, it's just a ** Rename LR0.cc as lr0.cc, why upper case? -** bench several bisons. -Enhance bench.pl with %b to run different bisons. - * Various -** Warnings -Warnings about type tags that are used in printer and dtors, but not -for symbols? - -** 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 @@ -95,9 +154,6 @@ 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: @@ -115,12 +171,6 @@ really possible? The test suite does not exercise this case. This shows that it would be interesting to manage to install skeleton coverage analysis to the test suite. -** Table definitions -It should be very easy to factor the definition of the various tables, -including the separation bw declaration and definition. See for -instance b4_table_define in lalr1.cc. This way, we could even factor -C vs. C++ definitions. - * From lalr1.cc to yacc.c ** Single stack Merging the three stacks in lalr1.cc simplified the code, prompted for @@ -132,21 +182,6 @@ 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 François: 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...). - - -* Documentation -Before releasing, make sure the documentation ("Understanding your -parser") refers to the current `output' format. * Report @@ -244,12 +279,6 @@ 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: @@ -267,37 +296,11 @@ Paul notes: tokens, either via escapes (e.g., "x\0y") or via a NUL byte in the source code. This should get fixed. -* --graph -Show reductions. - * Broken options ? ** %token-table ** 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 @@ -389,7 +392,7 @@ End: ----- -Copyright (C) 2001-2004, 2006, 2008-2012 Free Software Foundation, Inc. +Copyright (C) 2001-2004, 2006, 2008-2013 Free Software Foundation, Inc. This file is part of Bison, the GNU Compiler Compiler.