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diff --git a/gnuwin32/contrib/bison/2.4.1/bison-2.4.1-src/TODO b/gnuwin32/contrib/bison/2.4.1/bison-2.4.1-src/TODO deleted file mode 100644 index b2bca354..00000000 --- a/gnuwin32/contrib/bison/2.4.1/bison-2.4.1-src/TODO +++ /dev/null @@ -1,309 +0,0 @@ --*- outline -*- - -* 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. - -* 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 token, but one is -part of $default. Should we make the two reductions explicit, or just -keep $default? See the following point. - -** Disabled Reductions -See `tests/conflicts.at (Defaulted Conflicted Reduction)', and decide -what we want to do. - -** 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? - -** --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. - -** Statically check for potential ambiguities in GLR grammars. See -<http://www.i3s.unice.fr/~schmitz/papers.html#expamb> for an approach. - - -* 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 { $$ = $<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 - - exp: arith | bool; - arith: exp '+' exp; - bool: exp '&' exp; - -into - - exp: exp '+' exp | exp '&' exp; - -when there are no actions. This can significantly speed up some -grammars. I can't find the papers. In particular the book `LR -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? - - - -* Documentation - -** History/Bibliography -Some history of Bison and some bibliography would be most welcome. -Are there any Texinfo standards for bibliography? - - - -* Java, Fortran, etc. - - -* 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 -Show reductions. - -* Broken options ? -** %token-table -** Skeleton strategy -Must we keep %token-table? - -* src/print_graph.c -Find the best graph parameters. - -* 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. - -** 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++. - -** Improve the skeletons -Have them support yysymprint, yydestruct and so forth. - - -* 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 -move to partial orders (sounds like series/parallel orders to me). - -** 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 -character range, that character is written out in diagnostic messages, an -addition to the $undefined value. - -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 -that Bison writes to the bison.simple skeleton file. This way, I can remove -the current default rule $$ = $1 implementation, which causes a double -assignment to $$ which may not be OK under C++, replacing it with a -"default:" part within the switch statement. - -Note that the default rule $$ = $1, when typed, is perfectly OK under C, -but in the C++ implementation I made, this rule is different from -$<type_name>$ = $<type_name>1. I therefore think that one should implement -a Bison option where every typed default rule is explicitly written out -(same typed ruled can of course be grouped together). - -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 -implement this in such a way that other programs could use -lib/warnings.[ch]. - -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. - - -* Pre and post actions. -From: Florian Krohm <florian@edamail.fishkill.ibm.com> -Subject: YYACT_EPILOGUE -To: bug-bison@gnu.org -X-Sent: 1 week, 4 days, 14 hours, 38 minutes, 11 seconds ago - -The other day I had the need for explicitly building the parse tree. I -used %locations for that and defined YYLLOC_DEFAULT to call a function -that returns the tree node for the production. Easy. But I also needed -to assign the S-attribute to the tree node. That cannot be done in -YYLLOC_DEFAULT, because it is invoked before the action is executed. -The way I solved this was to define a macro YYACT_EPILOGUE that would -be invoked after the action. For reasons of symmetry I also added -YYACT_PROLOGUE. Although I had no use for that I can envision how it -might come in handy for debugging purposes. -All is needed is to add - -#if YYLSP_NEEDED - YYACT_EPILOGUE (yyval, (yyvsp - yylen), yylen, yyloc, (yylsp - yylen)); -#else - YYACT_EPILOGUE (yyval, (yyvsp - yylen), yylen); -#endif - -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. - -* Better graphics -Equip the parser with a means to create the (visual) parse tree. - ------ - -Copyright (C) 2001, 2002, 2003, 2004, 2006 Free Software Foundation, -Inc. - -This file is part of Bison, the GNU Compiler Compiler. - -This program 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 3 of the License, or -(at your option) any later version. - -This program 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 this program. If not, see <http://www.gnu.org/licenses/>. |