-*- outline -*-
+* URGENT: Documenting C++ output
+Write a first documentation for C++ output.
+
+* 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?
+
+* 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...
+
+* 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, ?).
+
+* Error messages
+Some are really funky. For instance
+
+ type clash (`%s' `%s') on default action
+
+is really weird. Revisit them all.
+
+* Report documentation
+Extend with error. The hard part will probably be finding the right
+rule so that a single state does not exhibit to 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?
+
* 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_
char *sval;
}
-* Experimental report features
-Decide whether they should be enabled, or optional. For instance, on:
-
- input:
- exp
- | input exp
- ;
-
- exp:
- token1 "1"
- | token2 "2"
- | token3 "3"
- ;
-
- token1: token;
- token2: token;
- token3: token;
-
-the traditional Bison reports:
-
- state 0
-
- $axiom -> . input $ (rule 0)
-
- token shift, and go to state 1
-
- input go to state 2
- exp go to state 3
- token1 go to state 4
- token2 go to state 5
- token3 go to state 6
-
- state 1
-
- token1 -> token . (rule 6)
- token2 -> token . (rule 7)
- token3 -> token . (rule 8)
-
- "2" reduce using rule 7 (token2)
- "3" reduce using rule 8 (token3)
- $default reduce using rule 6 (token1)
-
-while with --trace, i.e., when enabling both the display of non-core
-item sets and the display of lookaheads, Bison now displays:
-
- state 0
-
- $axiom -> . input $ (rule 0)
- input -> . exp (rule 1)
- input -> . input exp (rule 2)
- exp -> . token1 "1" (rule 3)
- exp -> . token2 "2" (rule 4)
- exp -> . token3 "3" (rule 5)
- token1 -> . token (rule 6)
- token2 -> . token (rule 7)
- token3 -> . token (rule 8)
-
- token shift, and go to state 1
-
- input go to state 2
- exp go to state 3
- token1 go to state 4
- token2 go to state 5
- token3 go to state 6
-
- state 1
-
- token1 -> token . ["1"] (rule 6)
- token2 -> token . ["2"] (rule 7)
- token3 -> token . ["3"] (rule 8)
-
- "2" reduce using rule 7 (token2)
- "3" reduce using rule 8 (token3)
- $default reduce using rule 6 (token1)
-
-so decide whether this should be an option, or always enabled. I'm in
-favor of making it the default, but maybe we should tune the output to
-distinguish core item sets from non core:
-
- state 0
- Core:
- $axiom -> . input $ (rule 0)
-
- Derived:
- input -> . exp (rule 1)
- input -> . input exp (rule 2)
- exp -> . token1 "1" (rule 3)
- exp -> . token2 "2" (rule 4)
- exp -> . token3 "3" (rule 5)
- token1 -> . token (rule 6)
- token2 -> . token (rule 7)
- token3 -> . token (rule 8)
-
- token shift, and go to state 1
-
- input go to state 2
- exp go to state 3
- token1 go to state 4
- token2 go to state 5
- token3 go to state 6
-
-
-Note that the same questions applies to --graph.
+* --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.
* Coding system independence
Paul notes:
PDP-10 ports :-) but they should probably be documented
somewhere.
-* Output directory
-Akim:
-
-| I consider this to be a bug in bison:
-|
-| /tmp % mkdir src
-| /tmp % cp ~/src/bison/tests/calc.y src
-| /tmp % mkdir build && cd build
-| /tmp/build % bison ../src/calc.y
-| /tmp/build % cd ..
-| /tmp % ls -l build src
-| build:
-| total 0
-|
-| src:
-| total 32
-| -rw-r--r-- 1 akim lrde 27553 oct 2 16:31 calc.tab.c
-| -rw-r--r-- 1 akim lrde 3335 oct 2 16:31 calc.y
-|
-|
-| Would it be safe to change this behavior to something more reasonable?
-| Do you think some people depend upon this?
-
-Jim:
-
-Is it that behavior documented?
-If so, then it's probably not reasonable to change it.
-I've Cc'd the automake list, because some of automake's
-rules use bison through $(YACC) -- though I'll bet they
-all use it in yacc-compatible mode.
-
-Pavel:
-
-Hello, Jim and others!
-
-> Is it that behavior documented?
-> If so, then it's probably not reasonable to change it.
-> I've Cc'd the automake list, because some of automake's
-> rules use bison through $(YACC) -- though I'll bet they
-> all use it in yacc-compatible mode.
-
-Yes, Automake currently used bison in Automake-compatible mode, but it
-would be fair for Automake to switch to the native mode as long as the
-processed files are distributed and "missing" emulates bison.
-
-In any case, the makefiles should specify the output file explicitly
-instead of relying on weird defaults.
-
-> | src:
-> | total 32
-> | -rw-r--r-- 1 akim lrde 27553 oct 2 16:31 calc.tab.c
-> | -rw-r--r-- 1 akim lrde 3335 oct 2 16:31 calc.y
-
-This is not _that_ ugly as it seems - with Automake you want to put
-sources where they belong - to the source directory.
-
-> | This is not _that_ ugly as it seems - with Automake you want to put
-> | sources where they belong - to the source directory.
->
-> The difference source/build you are referring to is based on Automake
-> concepts. They have no sense at all for tools such as bison or gcc
-> etc. They have input and output. I do not want them to try to grasp
-> source/build. I want them to behave uniformly: output *here*.
-
-I realize that.
-
-It's unfortunate that the native mode of Bison behaves in a less uniform
-way than the yacc mode. I agree with your point. Bison maintainters may
-want to fix it along with the documentation.
-
-
* Unit rules
Maybe we could expand unit rules, i.e., transform
exp: exp '+' exp | exp '&' exp;
when there are no actions. This can significantly speed up some
-grammars.
+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?
* Stupid error messages
An example shows it easily:
tests/testsuite.dir/51 % echo "()" | ./calc
1.2-1.3: parse error, unexpected ')', expecting error or "number" or '-' or '('
-* 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...
-
* 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.
A round of memory leak clean ups would be most welcome. Dmalloc,
Checker GCC, Electric Fence, or Valgrind: you chose your tool.
-* Memory leaks in the parser
-The same applies to the generated parsers. In particular, this is
-critical for user data: when aborting a parsing, when handling the
-error token etc., we often throw away yylval without giving a chance
-of cleaning it up to the user.
-
* --graph
Show reductions. []
See if we can integrate backtracking in Bison. Contact the BTYacc
maintainers.
-* Automaton report
-Display more clearly the lookaheads for each item.
-
* RR conflicts
See if we can use precedence between rules to solve RR conflicts. See
what POSIX says.
This will be possible with a Bison parser for the grammar, as it will
make it much easier to extend the grammar.
-* Parsing grammars
-Rewrite the reader in Flex/Bison. There will be delicate parts, in
-particular, expect the scanner to be hard to write. Many interesting
-features cannot be implemented without such a new reader.
-
-* Presentation of the report file
-From: "Baum, Nathan I" <s0009525@chelt.ac.uk>
-Subject: Token Alias Bug
-To: "'bug-bison@gnu.org'" <bug-bison@gnu.org>
-
-I've also noticed something, that whilst not *wrong*, is inconvienient: I
-use the verbose mode to help find the causes of unresolved shift/reduce
-conflicts. However, this mode insists on starting the .output file with a
-list of *resolved* conflicts, something I find quite useless. Might it be
-possible to define a -v mode, and a -vv mode -- Where the -vv mode shows
-everything, but the -v mode only tells you what you need for examining
-conflicts? (Or, perhaps, a "*** This state has N conflicts ***" marker above
-each state with conflicts.)
-
* $undefined
From Hans:
- If the Bison generated parser experiences an undefined number in the
Note: Robert Anisko handles this. He knows how to do it.
-* Documenting C++ output
-Write a first documentation for C++ output.
-
* 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
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.
+
-----
Copyright (C) 2001, 2002 Free Software Foundation, Inc.
projects / bison.git / blobdiff