-*- outline -*-
+* documentation
+Explain $axiom (and maybe change its name: BTYacc names it goal).
+Complete the glossary (item, axiom, ?).
+
+* 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_
+it will be important for the various bits to define their needs in
+%union.
+
+When implementing multiple-%union support, bare the following in mind:
+
+- when --yacc, this must be flagged as an error. Don't make it fatal
+ though.
+
+- The #line must now appear *inside* the definition of yystype.
+ Something like
+
+ {
+ #line 12 "foo.y"
+ int ival;
+ #line 23 "foo.y"
+ char *sval;
+ }
+
+* --report=conflict-path
+Provide better assistance for understanding the conflicts by providing
+a sample text exhibiting the (LALR) ambiguity.
+
+* report
+Solved conflicts should not be reported in the beginning of the file.
+Rather they should be reported within each state description. Also,
+now that the symbol providing the precedence of a rule is kept, it is
+possible to explain why a conflict was solved this way. E.g., instead
+of
+
+ Conflict in state 8 between rule 2 and token '+' resolved as reduce.
+
+we can (in state 8) report something like
+
+ Conflict between rule 2 and token '+' resolved as reduce
+ because '*' < '+'.
+
+or something like that.
+
* Coding system independence
Paul notes:
PDP-10 ports :-) but they should probably be documented
somewhere.
-* Using enums instead of int for tokens.
-Paul suggests:
-
- #ifndef YYTOKENTYPE
- # if defined (__STDC__) || defined (__cplusplus)
- /* Put the tokens into the symbol table, so that GDB and other debuggers
- know about them. */
- enum yytokentype {
- FOO = 256,
- BAR,
- ...
- };
- /* POSIX requires `int' for tokens in interfaces. */
- # define YYTOKENTYPE int
- # endif
- #endif
- #define FOO 256
- #define BAR 257
- ...
-
-> I'm in favor of
->
-> %token FOO 256
-> %token BAR 257
->
-> and Bison moves error into 258.
-
-Yes, I think that's a valid extension too, if the user doesn't define
-the token number for error.
-
* Output directory
Akim:
error token etc., we often throw away yylval without giving a chance
of cleaning it up to the user.
-* NEWS
-Sort from 1.31 NEWS.
-
-* Prologue
-The %union is declared after the user C declarations. It can be
-a problem if YYSTYPE is declared after the user part. []
-
-Actually, the real problem seems that the %union ought to be output
-where it was defined. For instance, in gettext/intl/plural.y, we
-have:
-
- %{
- ...
- #include "gettextP.h"
- ...
- %}
-
- %union {
- unsigned long int num;
- enum operator op;
- struct expression *exp;
- }
-
- %{
- ...
- static int yylex PARAMS ((YYSTYPE *lval, const char **pexp));
- ...
- %}
-
-Where the first part defines struct expression, the second uses it to
-define YYSTYPE, and the last uses YYSTYPE. Only this order is valid.
-
* --graph
Show reductions. []
** %no-lines [ok]
** %no-parser []
** %pure-parser []
-** %semantic-parser []
** %token-table []
** Options which could use parse_dquoted_param ().
Maybe transfered in lex.c.
makes it impossible to have modular precedence information. We should
move to partial orders.
+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 Bison.
+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
+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.
+
+* 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
+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.
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projects / bison.git / blobdiff