* NEWS (2.3a+): Mention yesterday's state-removal change.

[bison.git] / TODO

diff --git a/TODO b/TODO
index b21ed19fde0ac7cbb93c7e6288698d057765c5e5..94bd12c8e76fe288fa5320633b1e69af06bd6ad5 100644 (file)
--- a/TODO
+++ b/TODO
@@ -1,38 +1,35 @@
 -*- outline -*-
 
 -*- outline -*-
 

-* URGENT: Documenting C++ output
-Write a first documentation for C++ output.
+* Header guards

 
 

-
-* Documentation
-Before releasing, make sure the documentation refers to the current
-`output' format.
+From Franc,ois: should we keep the directory part in the CPP guard?

 
 
 
 

-* Error messages
-Some are really funky.  For instance
+* Yacc.c: CPP Macros

 
 

-       type clash (`%s' `%s') on default action
+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...).

 
 

-is really weird.  Revisit them all.

 
 

+* Installation

 
 

-* 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 $<foo>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,
 
 * 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 lookahead token, but one is

 part of $default.  Should we make the two reductions explicit, or just
 keep $default?  See the following point.
 
 part of $default.  Should we make the two reductions explicit, or just
 keep $default?  See the following point.
 


@@ -52,34 +49,73 @@ Provide better assistance for understanding the conflicts by providing
 a sample text exhibiting the (LALR) ambiguity.  See the paper from
 DeRemer and Penello: they already provide the algorithm.
 
 a sample text exhibiting the (LALR) ambiguity.  See the paper from
 DeRemer and Penello: they already provide the algorithm.
 

+** Statically check for potential ambiguities in GLR grammars.  See
+<http://www.i3s.unice.fr/~schmitz/papers.html#expamb> for an approach.
+

 
 * Extensions
 
 
 * Extensions
 

-** yyerror, 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...
+** 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

 
 

-** Several %unions
-I think this is a pleasant (but useless currently) feature, but in the
-future, I want a means to %include other bits of grammars, and _then_
-it will be important for the various bits to define their needs in
-%union.
+       baz: qux { $$ = $<foo>-1 + $<bar>0 + $1; }

 
 

-When implementing multiple-%union support, bare the following in mind:
+we should be able to have:

 
 

-- when --yacc, this must be flagged as an error.  Don't make it fatal
-  though.
+  foo($foo) bar($bar) baz($bar): qux($qux) { $baz = $foo + $bar + $qux; }

 
 

-- The #line must now appear *inside* the definition of yystype.
-  Something like
+Or something like this.

 
 

-       {
-       #line 12 "foo.y"
-         int ival;
-       #line 23 "foo.y"
-         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
 
 * Unit rules
 Maybe we could expand unit rules, i.e., transform


@@ -110,12 +146,6 @@ Are there any Texinfo standards for bibliography?
 
 * Java, Fortran, etc.
 
 
 * Java, Fortran, etc.
 

-  Add support for languages other than C and C++.  Here is a proposed
-  patch for Java:
-
-  <http://www.goice.co.jp/member/mo/hack-progs/bison-java.html>
-
-

 
 * Coding system independence
 Paul notes:
 
 * Coding system independence
 Paul notes:


@@ -130,49 +160,28 @@ Paul notes:
        PDP-10 ports :-) but they should probably be documented
        somewhere.
 
        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
 
 * --graph

-Show reductions.       []
+Show reductions.

 
 * Broken options ?
 
 * Broken options ?

-** %no-lines           [ok]
-** %no-parser          []
-** %pure-parser                []
-** %token-table                []
-** Options which could use parse_dquoted_param ().
-Maybe transferred in lex.c.
-*** %skeleton          [ok]
-*** %output            []
-*** %file-prefix       []
-*** %name-prefix       []
-
-** Skeleton strategy.  []
-Must we keep %no-parser?
-            %token-table?
-*** New skeletons.     []
+** %no-parser
+** %token-table
+** Skeleton strategy
+Must we keep %no-parser?  %token-table?

 
 * src/print_graph.c
 
 * src/print_graph.c

-Find the best graph parameters.        []
-
-* doc/bison.texinfo
-** Update
-informations about ERROR_VERBOSE.      []
-** Add explanations about
-skeleton muscles.      []
-%skeleton.             []
-
-* testsuite
-** 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.
+Find the best graph parameters.

 
 * BTYacc
 
 * 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 <de-boy_c@epita.fr> 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
 
 ** Keeping the conflicted actions
 First, analyze the differences between byacc and btyacc (I'm referring


@@ -198,9 +207,6 @@ It is unfortunate that there is a total order for precedence.  It
 makes it impossible to have modular precedence information.  We should
 move to partial orders (sounds like series/parallel orders to me).
 
 makes it impossible to have modular precedence information.  We should
 move to partial orders (sounds like series/parallel orders to me).
 

-This will be possible with a Bison parser for the grammar, as it will
-make it much easier to extend the grammar.
-

 ** Correlation b/w precedence and associativity
 Also, I fail to understand why we have to assign the same
 associativity to operators with the same precedence.  For instance,
 ** Correlation b/w precedence and associativity
 Also, I fail to understand why we have to assign the same
 associativity to operators with the same precedence.  For instance,


@@ -280,27 +286,27 @@ at the proper place to bison.simple. Ditto for YYACT_PROLOGUE.
 I was wondering what you think about adding YYACT_PROLOGUE/EPILOGUE
 to bison. If you're interested, I'll work on a patch.
 
 I was wondering what you think about adding YYACT_PROLOGUE/EPILOGUE
 to bison. If you're interested, I'll work on a patch.
 

-* Move to Graphviz
-Well, VCG seems really dead.  Move to Graphviz instead.  Also, equip
-the parser with a means to create the (visual) parse tree.
+* Better graphics
+Equip 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, 2006 Free Software Foundation,
+Inc.

 
 

-This file is part of GNU Bison.
+This file is part of Bison, the GNU Compiler Compiler.

 
 

-GNU Bison is free software; you can redistribute it and/or modify
+Bison is free software; you can redistribute it and/or modify

 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 2, or (at your option)
 any later version.
 
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 2, or (at your option)
 any later version.
 

-GNU Bison is distributed in the hope that it will be useful,
+Bison is distributed in the hope that it will be useful,

 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 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
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 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.