-*- outline -*-
+* URGENT: Documenting C++ output
+Write a first documentation for C++ output.
-* URGENT: Prologue
-The %union is declared after the user C declarations. It can be
-a problem if YYSTYPE is declared after the user part.
+* 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?
-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"
- ...
- %}
+* 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...
- %union {
- unsigned long int num;
- enum operator op;
- struct expression *exp;
+* documentation
+Explain $axiom (and maybe change its name: BTYacc names it `goal',
+byacc `$accept', probably based on AT&T Yacc). 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;
}
- %{
- ...
- 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.
-
-Note that we have the same problem with GCC.
-
-I suggest splitting the prologue into pre-prologue and post-prologue.
-The reason is that:
-
-1. we keep language independance as it is the skeleton that joins the
-two prologues (there is no need for the engine to encode union yystype
-and to output it inside the prologue, which breaks the language
-independance of the generator)
-
-2. that makes it possible to have several %union in input. 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.
+* --report=conflict-path
+Provide better assistance for understanding the conflicts by providing
+a sample text exhibiting the (LALR) ambiguity.
* 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:
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.
** %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.
-* Parsing grammars
-Rewrite the reader in Bison.
-
-* Problems with aliases
-From: "Baum, Nathan I" <s0009525@chelt.ac.uk>
-Subject: Token Alias Bug
-To: "'bug-bison@gnu.org'" <bug-bison@gnu.org>
-
-I've noticed a bug in bison. Sadly, our eternally wise sysadmins won't let
-us use CVS, so I can't find out if it's been fixed already...
-
-Basically, I made a program (in flex) that went through a .y file looking
-for "..."-tokens, and then outputed a %token
-line for it. For single-character ""-tokens, I reasoned, I could just use
-[%token 'A' "A"]. However, this causes Bison to output a [#define 'A' 65],
-which cppp chokes on, not unreasonably. (And even if cppp didn't choke, I
-obviously wouldn't want (char)'A' to be replaced with (int)65 throughout my
-code.
-
-Bison normally forgoes outputing a #define for a character token. However,
-it always outputs an aliased token -- even if the token is an alias for a
-character token. We don't want that. The problem is in /output.c/, as I
-recall. When it outputs the token definitions, it checks for a character
-token, and then checks for an alias token. If the character token check is
-placed after the alias check, then it works correctly.
-
-Alias tokens seem to be something of a kludge. What about an [%alias "..."]
-command...
-
- %alias T_IF "IF"
-
-Hmm. I can't help thinking... What about a --generate-lex option that
-creates an .l file for the alias tokens used... (Or an option to make a
-gperf file, etc...)
-
-* 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.)
+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.
* $undefined
From Hans:
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
projects / bison.git / blobdiff