(STRING_FREE): Don't use FLEX_PREFIX (last_string)

[bison.git] / TODO

diff --git a/TODO b/TODO
index 9750583007fa39da6b42614a8d6f68a26523cf5d..96d5d2a489e05c40162e500583536b2584537d1e 100644 (file)
--- a/TODO
+++ b/TODO
@@ -1,91 +1,125 @@
 -*- outline -*-
 
 -*- outline -*-
 

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

 
 

-* Report and 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
-part of $default.  Should we make the two reductions explicit, or just
-keep $default?  See the following point.
+From Franc,ois: should we keep the directory part in the CPP guard?

 
 

-* Report and Disabled Reductions
-See `tests/conflicts.at (Defaulted Conflicted Reduction)', and decide
-what we want to do.

 
 

-* 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?
+* 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
+
+** Disable installation of yacc.
+
+Add an option to 'configure' that allows people to install Bison
+without installing the yacc wrapper script or the rarely-used little
+yacc library required by Posix.  This is for people who prefer some
+other implementation of yacc.
+
+* Documentation
+Before releasing, make sure the documentation ("Understanding your
+parser") refers to the current `output' format.

 
 

-* yyerror, yyprint 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...
+* lalr1.cc
+** vector
+Move to using vector, drop stack.hh.

 
 

-* documentation
-Explain $axiom (and maybe change its name: BTYacc names it `goal',
-byacc `$accept' probably based on AT&T Yacc, Meta `Start'...).
-Complete the glossary (item, axiom, ?).  Should we also rename `$'?
-BYacc uses `$end'.  `$eof' is attracting, but after all we may be
-parsing a string, a stream etc.
+** I18n
+Catch up with yacc.c.

 
 

-* Error messages
-Some are really funky.  For instance
+* Report

 
 

-       type clash (`%s' `%s') on default action
+**  GLR
+How would Paul like to display the conflicted actions?  In particular,
+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.

 
 

-is really weird.  Revisit them all.
+** Disabled Reductions
+See `tests/conflicts.at (Defaulted Conflicted Reduction)', and decide
+what we want to do.

 
 

-* Report documentation
+** Documentation

 Extend with error productions.  The hard part will probably be finding
 the right rule so that a single state does not exhibit too many yet
 undocumented ``features''.  Maybe an empty action ought to be
 presented too.  Shall we try to make a single grammar with all these
 features, or should we have several very small grammars?
 
 Extend with error productions.  The hard part will probably be finding
 the right rule so that a single state does not exhibit too many yet
 undocumented ``features''.  Maybe an empty action ought to be
 presented too.  Shall we try to make a single grammar with all these
 features, or should we have several very small grammars?
 

-* Documentation
-Some history of Bison and some bibliography would be most welcome.
-Are there any Texinfo standards for bibliography?
+** --report=conflict-path
+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.

 
 

-* 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.

 
 

-When implementing multiple-%union support, bare the following in mind:
+* Extensions

 
 

-- when --yacc, this must be flagged as an error.  Don't make it fatal
-  though.
+** 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:

 
 

-- The #line must now appear *inside* the definition of yystype.
-  Something like
+       exp (res): exp (a) '+' exp (b) { $res = $a + $b; };

 
 

-       {
-       #line 12 "foo.y"
-         int ival;
-       #line 23 "foo.y"
-         char *sval;
-       }
+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...

 
 

-* --report=conflict-path
-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.
+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:

 
 

-* Coding system independence
-Paul notes:
+       r:exp -> a:exp '+' b:exp { r = a + b; };

 
 

-       Currently Bison assumes 8-bit bytes (i.e. that UCHAR_MAX is
-       255).  It also assumes that the 8-bit character encoding is
-       the same for the invocation of 'bison' as it is for the
-       invocation of 'cc', but this is not necessarily true when
-       people run bison on an ASCII host and then use cc on an EBCDIC
-       host.  I don't think these topics are worth our time
-       addressing (unless we find a gung-ho volunteer for EBCDIC or
-       PDP-10 ports :-) but they should probably be documented
-       somewhere.
+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 { $$ = $<foo>-1 + $<bar>0 + $1; }
+
+we should be able to have:
+
+  foo($foo) bar($bar) baz($bar): qux($qux) { $baz = $foo + $bar + $qux; }
+
+Or something like this.
+
+** %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


@@ -104,92 +138,113 @@ parsing: Theory and Practice' is impossible to find, but according to
 `Parsing Techniques: a Practical Guide', it includes information about
 this issue.  Does anybody have it?
 
 `Parsing Techniques: a Practical Guide', it includes information about
 this issue.  Does anybody have it?
 

-* Stupid error messages
-An example shows it easily:
-
-src/bison/tests % ./testsuite -k calc,location,error-verbose -l
-GNU Bison 1.49a test suite test groups:
-
- NUM: FILENAME:LINE      TEST-GROUP-NAME
-      KEYWORDS
-
-  51: calc.at:440        Calculator --locations --yyerror-verbose
-  52: calc.at:442        Calculator --defines --locations --name-prefix=calc --verbose --yacc --yyerror-verbose
-  54: calc.at:445        Calculator --debug --defines --locations --name-prefix=calc --verbose --yacc --yyerror-verbose
-src/bison/tests % ./testsuite 51 -d
-## --------------------------- ##
-## GNU Bison 1.49a test suite. ##
-## --------------------------- ##
- 51: calc.at:440       ok
-## ---------------------------- ##
-## All 1 tests were successful. ##
-## ---------------------------- ##
-src/bison/tests % cd ./testsuite.dir/51
-tests/testsuite.dir/51 % echo "()" | ./calc
-1.2-1.3: parse error, unexpected ')', expecting error or "number" or '-' or '('
-
-* 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.
-
-* Memory leaks in the generator
-A round of memory leak clean ups would be most welcome.  Dmalloc,
-Checker GCC, Electric Fence, or Valgrind: you chose your tool.
+
+
+* Documentation
+
+** History/Bibliography
+Some history of Bison and some bibliography would be most welcome.
+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.
+  <http://troi.lincom-asg.com/~rjamison/byacc/>
+
+- Bison Java
+  which is based on Bison.
+  <http://www.goice.co.jp/member/mo/hack-progs/bison-java.html>
+
+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:
+
+       Currently Bison assumes 8-bit bytes (i.e. that UCHAR_MAX is
+       255).  It also assumes that the 8-bit character encoding is
+       the same for the invocation of 'bison' as it is for the
+       invocation of 'cc', but this is not necessarily true when
+       people run bison on an ASCII host and then use cc on an EBCDIC
+       host.  I don't think these topics are worth our time
+       addressing (unless we find a gung-ho volunteer for EBCDIC or
+       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 transfered 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.        []
+Find the best graph parameters.

 
 

-* doc/bison.texinfo
-** Update
-informations about ERROR_VERBOSE.      []
-** Add explainations about
-skeleton muscles.      []
-%skeleton.             []
+* BTYacc
+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.

 
 

-* testsuite
-** tests/pure-parser.at        []
-New tests.
+** Keeping the conflicted actions
+First, analyze the differences between byacc and btyacc (I'm referring
+to the executables).  Find where the conflicts are preserved.

 
 

-* input synclines
-Some users create their foo.y files, and equip them with #line.  Bison
-should recognize these, and preserve them.
+** 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.

 
 

-* BTYacc
-See if we can integrate backtracking in Bison.  Contact the BTYacc
-maintainers.
+** Adjust the skeletons
+Import the skeletons for C and C++.
+
+** Improve the skeletons
+Have them support yysymprint, yydestruct and so forth.

 
 

-* RR conflicts
-See if we can use precedence between rules to solve RR conflicts.  See
-what POSIX says.

 
 * Precedence
 
 * Precedence

+
+** Partial order

 It is unfortunate that there is a total order for precedence.  It
 makes it impossible to have modular precedence information.  We should
 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.
+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.
 
 
 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,
+why can't I decide that the precedence of * and / is the same, but the
+latter is nonassoc?
+
+If there is really no profound motivation, we should find a new syntax
+to allow specifying this.
+
+** RR conflicts
+See if we can use precedence between rules to solve RR conflicts.  See
+what POSIX says.
+
+

 * $undefined
 From Hans:
 - If the Bison generated parser experiences an undefined number in the
 * $undefined
 From Hans:
 - If the Bison generated parser experiences an undefined number in the


@@ -198,6 +253,7 @@ addition to the $undefined value.
 
 Suggest: Change the name $undefined to undefined; looks better in outputs.
 
 
 Suggest: Change the name $undefined to undefined; looks better in outputs.
 

+

 * Default Action
 From Hans:
 - For use with my C++ parser, I transported the "switch (yyn)" statement
 * Default Action
 From Hans:
 - For use with my C++ parser, I transported the "switch (yyn)" statement


@@ -214,6 +270,7 @@ a Bison option where every typed default rule is explicitly written out
 
 Note: Robert Anisko handles this.  He knows how to do it.
 
 
 Note: Robert Anisko handles this.  He knows how to do it.
 

+

 * Warnings
 It would be nice to have warning support.  See how Autoconf handles
 them, it is fairly well described there.  It would be very nice to
 * Warnings
 It would be nice to have warning support.  See how Autoconf handles
 them, it is fairly well described there.  It would be very nice to


@@ -224,6 +281,7 @@ Don't work on this without first announcing you do, as I already have
 thought about it, and know many of the components that can be used to
 implement it.
 
 thought about it, and know many of the components that can be used to
 implement it.
 

+

 * Pre and post actions.
 From: Florian Krohm <florian@edamail.fishkill.ibm.com>
 Subject: YYACT_EPILOGUE
 * Pre and post actions.
 From: Florian Krohm <florian@edamail.fishkill.ibm.com>
 Subject: YYACT_EPILOGUE


@@ -258,21 +316,22 @@ 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.