X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/217598dadc1d5aa72f430b1ac5584de8f385b596..8bb4c753e2d626ee90460e6d9f9cbaa2cd1f560d:/TODO?ds=sidebyside diff --git a/TODO b/TODO index 49775d18..a44f64ec 100644 --- a/TODO +++ b/TODO @@ -1,38 +1,33 @@ -*- outline -*- -* URGENT: Documenting C++ output -Write a first documentation for C++ output. +* Header guards +From Franc,ois: should we keep the directory part in the CPP guard? -* Documentation -Before releasing, make sure the documentation refers to the current -`output' format. - - -* Error messages -Some are really funky. For instance - type clash (`%s' `%s') on default action +* Yacc.c: CPP Macros -is really weird. Revisit them all. +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...). -* read_pipe.c -This is not portable to DOS for instance. Implement a more portable -scheme. Sources of inspiration include GNU diff, and Free Recode. - +* Documentation +Before releasing, make sure the documentation ("Understanding your +parser") refers to the current `output' format. -* value_components_used -Was defined but not used: where was it coming from? It can't be to -check if %union is used, since the user is free to $n on her -union, doesn't she? +* lalr1.cc +** vector +Move to using vector, drop stack.hh. +** I18n +Catch up with yacc.c. * Report ** GLR How would Paul like to display the conflicted actions? In particular, -what when two reductions are possible on a given lookahead, but one is +what when two reductions are possible on a given look-ahead token, but one is part of $default. Should we make the two reductions explicit, or just keep $default? See the following point. @@ -53,12 +48,49 @@ a sample text exhibiting the (LALR) ambiguity. See the paper from DeRemer and Penello: they already provide the algorithm. -* Extentions +* Extensions + +** Labeling the symbols +Have a look at the Lemon parser generator: instead of $1, $2 etc. they +can name the values. This is much more pleasant. For instance: + + exp (res): exp (a) '+' exp (b) { $res = $a + $b; }; + +I love this. I have been bitten too often by the removal of the +symbol, and forgetting to shift all the $n to $n-1. If you are +unlucky, it compiles... + +But instead of using $a etc., we can use regular variables. And +instead of using (), I propose to use `:' (again). Paul suggests +supporting `->' in addition to `:' to separate LHS and RHS. In other +words: + + r:exp -> a:exp '+' b:exp { r = a + b; }; + +That requires an significant improvement of the grammar parser. Using +GLR would be nice. It also requires that Bison know the type of the +symbols (which will be useful for %include anyway). So we have some +time before... + +Note that there remains the problem of locations: `@r'? + + +** $-1 +We should find a means to provide an access to values deep in the +stack. For instance, instead of + + baz: qux { $$ = $-1 + $0 + $1; } + +we should be able to have: + + foo($foo) bar($bar) baz($bar): qux($qux) { $baz = $foo + $bar + $qux; } -** yyerror, yysymprint interface +Or something like this. + +** yysymprint interface It should be improved, in particular when using Bison features such as -locations, and YYPARSE_PARAMS. For the time being, it is recommended -to #define yyerror and yyprint to steal internal variables... +locations, and YYPARSE_PARAMS. For the time being, it is almost +recommended to yyprint to steal internal variables... ** Several %unions I think this is a pleasant (but useless currently) feature, but in the @@ -81,6 +113,31 @@ When implementing multiple-%union support, bare the following in mind: char *sval; } +** %if and the like +It should be possible to have %if/%else/%endif. The implementation is +not clear: should it be lexical or syntactic. Vadim Maslow thinks it +must be in the scanner: we must not parse what is in a switched off +part of %if. Akim Demaille thinks it should be in the parser, so as +to avoid falling into another CPP mistake. + +** -D, --define-muscle NAME=VALUE +To define muscles via cli. Or maybe support directly NAME=VALUE? + +** XML Output +There are couple of available extensions of Bison targeting some XML +output. Some day we should consider including them. One issue is +that they seem to be quite orthogonal to the parsing technique, and +seem to depend mostly on the possibility to have some code triggered +for each reduction. As a matter of fact, such hooks could also be +used to generate the yydebug traces. Some generic scheme probably +exists in there. + +XML output for GNU Bison and gcc + http://www.cs.may.ie/~jpower/Research/bisonXML/ + +XML output for GNU Bison + http://yaxx.sourceforge.net/ + * Unit rules Maybe we could expand unit rules, i.e., transform @@ -108,6 +165,25 @@ Are there any Texinfo standards for bibliography? +* Java, Fortran, etc. + + +** Java + +There are a couple of proposed outputs: + +- BYACC/J + which is based on Byacc. + + +- Bison Java + which is based on Bison. + + +Sebastien Serrurier (serrur_s@epita.fr) is working on this: he is +expected to contact the authors, design the output, and implement it +into Bison. + * Coding system independence Paul notes: @@ -122,27 +198,19 @@ Paul notes: PDP-10 ports :-) but they should probably be documented somewhere. - + More importantly, Bison does not currently allow NUL bytes in + 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 ? -** %no-lines [ok] ** %no-parser [] -** %pure-parser [] ** %token-table [] -** Options which could use parse_dquoted_param (). -Maybe transfered in lex.c. -*** %skeleton [ok] -*** %output [] -*** %file-prefix [] -*** %name-prefix [] - ** Skeleton strategy. [] Must we keep %no-parser? %token-table? -*** New skeletons. [] * src/print_graph.c Find the best graph parameters. [] @@ -150,7 +218,7 @@ Find the best graph parameters. [] * doc/bison.texinfo ** Update informations about ERROR_VERBOSE. [] -** Add explainations about +** Add explanations about skeleton muscles. [] %skeleton. [] @@ -158,20 +226,19 @@ skeleton muscles. [] ** tests/pure-parser.at [] New tests. -* input synclines -Some users create their foo.y files, and equip them with #line. Bison -should recognize these, and preserve them. - * BTYacc -See if we can integrate backtracking in Bison. Contact the BTYacc -maintainers. +See if we can integrate backtracking in Bison. Charles-Henri de +Boysson is working on this, and already has some +results. Vadim Maslow, the maintainer of BTYacc was contacted, and we +stay in touch with him. 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 adjustements in +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. @@ -278,7 +345,7 @@ the parser with a means to create the (visual) parse tree. ----- -Copyright (C) 2001, 2002 Free Software Foundation, Inc. +Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc. This file is part of GNU Bison. @@ -294,5 +361,5 @@ GNU General Public License for more details. You should have received a copy of the GNU General Public License along with Bison; see the file COPYING. If not, write to -the Free Software Foundation, Inc., 59 Temple Place - Suite 330, -Boston, MA 02111-1307, USA. +the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, +Boston, MA 02110-1301, USA.