X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/6cbfbcc58c425fef062c4d759e5d43c56a9a194e..670ddffd5ba88d6d5baf6aa51803592687ae48b0:/TODO?ds=sidebyside diff --git a/TODO b/TODO index a6b677f6..607366b3 100644 --- a/TODO +++ b/TODO @@ -1,5 +1,19 @@ -*- 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 @@ -22,30 +36,9 @@ When implementing multiple-%union support, bare the following in mind: char *sval; } -* Language independent actions - -Currently bison, the generator, transforms $1, $$ and so forth into -direct C code, manipulating the stacks. This is problematic, because -(i) it means that if we want more languages, we need to update the -generator, and (ii), it forces names everywhere (e.g., the C++ -skeleton would be happy to use other naming schemes, and actually, -even other accessing schemes). - -Therefore we want - -1. the generator to replace $1, etc. by M4 macro invocations - (b4_dollar(1), b4_at(3), b4_dollar_dollar) etc. - -2. the skeletons to define these macros. - -But currently the actions are double-quoted, to protect them from M4 -evaluation. So we need to: - -3. stop quoting them - -4. change the [ and ] in the actions into @<:@ and @:>@ - -5. extend the postprocessor to maps these back onto [ and ]. +* --report=conflict-path +Provide better assistance for understanding the conflicts by providing +a sample text exhibiting the (LALR) ambiguity. * Coding system independence Paul notes: @@ -60,26 +53,6 @@ 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 - ... - * Output directory Akim: @@ -215,7 +188,6 @@ 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. @@ -316,40 +288,13 @@ 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. -* Parsing grammars -Rewrite the reader in Bison. +This will be possible with a Bison parser for the grammar, as it will +make it much easier to extend the grammar. -* Problems with aliases -From: "Baum, Nathan I" -Subject: Token Alias Bug -To: "'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...) +* 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" @@ -365,7 +310,6 @@ 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 @@ -388,6 +332,21 @@ $$ = $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 Subject: YYACT_EPILOGUE