TODO: update.

[bison.git] / TODO

diff --git a/TODO b/TODO
index addd135d41d10ab571743c25074663eaaeba4d86..24af226c42ab757c223c919b968ead8d68ec916d 100644 (file)
--- a/TODO
+++ b/TODO
@@ -1,31 +1,11 @@
--*- outline -*-
-
 * Short term
-** Use syntax_error from the scanner?
-This would provide a means to raise syntax error from function called
-from the scanner.  Actually, there is no good solution to report a
-lexical error in general.  Usually they are kept at the scanner level
-only, ignoring the guilty token.  But that might not be the best bet,
-since we don't benefit from the syntactic error recovery.
-
-We still have the possibility to return an invalid token number, which
-does the trick.  But then the error message from the parser is poor
-(something like "unexpected $undefined").  Since the scanner probably
-already reported the error, we should directly enter error-recovery,
-without reporting the error message (i.e., YYERROR's semantics).
-
-Back to lalr1.cc (whose name is now quite unfortunate, since it also
-covers lr and ielr), if we support exceptions from yylex, should we
-propose a lexical_error in addition to syntax_error?  Should they have
-a common root, say parse_error?  Should syntax_error be renamed
-syntactic_error for consistency with lexical_error?
-
 ** Variable names.
 What should we name `variant' and `lex_symbol'?
 
 ** Use b4_symbol in all the skeleton
-Then remove the older system, including the tables generated by
-output.c
+Move its definition in the more standard places and deploy it in other
+skeletons.  Then remove the older system, including the tables
+generated by output.c
 
 ** Update the documentation on gnu.org
 
@@ -58,11 +38,11 @@ as lr0.cc, why upper case?
 ** bench several bisons.
 Enhance bench.pl with %b to run different bisons.
 
-** Use b4_symbol everywhere.
-Move its definition in the more standard places and deploy it in other
-skeletons.
-
 * Various
+** Warnings
+Warnings about type tags that are used in printer and dtors, but not
+for symbols?
+
 ** YYPRINT
 glr.c inherits its symbol_print function from c.m4, which supports
 YYPRINT.  But to use YYPRINT yytoknum is needed, which not defined by
@@ -118,50 +98,6 @@ so both 256 and 257 are "mysterious".
 ** YYFAIL
 It is seems to be *really* obsolete now, shall we remove it?
 
-** YYBACKUP
-There is no test about it, no examples in the doc, and I'm not sure
-what it should look like.  For instance what follows crashes.
-
-  %error-verbose
-  %debug
-  %pure-parser
-  %code {
-  # include <stdio.h>
-  # include <stdlib.h>
-  # include <assert.h>
-
-    static void yyerror (const char *msg);
-    static int yylex (YYSTYPE *yylval);
-  }
-  %%
-  exp:
-    'a'   { printf ("a: %d\n", $1); }
-  | 'b'   { YYBACKUP('a', 123); }
-  ;
-  %%
-  static int
-  yylex (YYSTYPE *yylval)
-  {
-    static char const input[] = "b";
-    static size_t toknum;
-    assert (toknum < sizeof input);
-    *yylval = (toknum + 1) * 10;
-    return input[toknum++];
-  }
-
-  static void
-  yyerror (const char *msg)
-  {
-    fprintf (stderr, "%s\n", msg);
-  }
-
-  int
-  main (void)
-  {
-    yydebug = !!getenv("YYDEBUG");
-    return yyparse ();
-  }
-
 ** yychar == yyempty_
 The code in yyerrlab reads:
 
@@ -198,7 +134,7 @@ some parts.
 
 * Header guards
 
-From Franc,ois: should we keep the directory part in the CPP guard?
+From François: should we keep the directory part in the CPP guard?
 
 
 * Yacc.c: CPP Macros
@@ -208,8 +144,6 @@ 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.
@@ -251,31 +185,6 @@ DeRemer and Penello: they already provide the algorithm.
 
 * 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
@@ -472,6 +381,12 @@ Here's a proposal for how a new implementation might look:
 
   http://lists.gnu.org/archive/html/bison-patches/2009-09/msg00086.html
 
+
+Local Variables:
+mode: outline
+coding: utf-8
+End:
+
 -----
 
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