glr.c: remove (broken) support for YYPRINT.

[bison.git] / TODO

diff --git a/TODO b/TODO
index 376ec1d7b97284197a00e0474855640c36c9a309..13c1f85877e1e1dd22ac69e3b1f8c629af0da95f 100644 (file)
--- a/TODO
+++ b/TODO
@@ -1,9 +1,11 @@
--*- outline -*-
-

 * Short term
 * Short term

+** Variable names.
+What should we name `variant' and `lex_symbol'?
+

 ** Use b4_symbol in all the skeleton
 ** 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
 
 
 ** Update the documentation on gnu.org
 


@@ -36,17 +38,10 @@ as lr0.cc, why upper case?
 ** bench several bisons.
 Enhance bench.pl with %b to run different bisons.
 
 ** 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
 * Various

-** 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
-glr.c.
-
-Anyway, IMHO YYPRINT is obsolete and should be restricted to yacc.c.
+** Warnings
+Warnings about type tags that are used in printer and dtors, but not
+for symbols?

 
 ** YYERRCODE
 Defined to 256, but not used, not documented.  Probably the token
 
 ** YYERRCODE
 Defined to 256, but not used, not documented.  Probably the token


@@ -96,59 +91,15 @@ so both 256 and 257 are "mysterious".
 ** YYFAIL
 It is seems to be *really* obsolete now, shall we remove it?
 
 ** 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:
 
       if (yychar <= YYEOF)
 ** yychar == yyempty_
 The code in yyerrlab reads:
 
       if (yychar <= YYEOF)

-       {
-         /* Return failure if at end of input.  */
-         if (yychar == YYEOF)
-           YYABORT;
-       }
+        {
+          /* Return failure if at end of input.  */
+          if (yychar == YYEOF)
+            YYABORT;
+        }

 
 There are only two yychar that can be <= YYEOF: YYEMPTY and YYEOF.
 But I can't produce the situation where yychar is YYEMPTY here, is it
 
 There are only two yychar that can be <= YYEOF: YYEMPTY and YYEOF.
 But I can't produce the situation where yychar is YYEMPTY here, is it


@@ -176,7 +127,7 @@ some parts.
 
 * Header guards
 
 
 * 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
 
 
 * Yacc.c: CPP Macros


@@ -186,14 +137,19 @@ They should not: it is not documented.  But if they need to, let's
 find something clean (not like YYLSP_NEEDED...).
 
 
 find something clean (not like YYLSP_NEEDED...).
 
 

-* Installation
-

 * Documentation
 Before releasing, make sure the documentation ("Understanding your
 parser") refers to the current `output' format.
 
 * Report
 
 * Documentation
 Before releasing, make sure the documentation ("Understanding your
 parser") refers to the current `output' format.
 
 * Report
 

+** Figures
+Some statistics about the grammar and the parser would be useful,
+especially when asking the user to send some information about the
+grammars she is working on.  We should probably also include some
+information about the variables (I'm not sure for instance we even
+specify what LR variant was used).
+

 **  GLR
 How would Paul like to display the conflicted actions?  In particular,
 what when two reductions are possible on a given lookahead token, but one is
 **  GLR
 How would Paul like to display the conflicted actions?  In particular,
 what when two reductions are possible on a given lookahead token, but one is


@@ -222,36 +178,11 @@ DeRemer and Penello: they already provide the algorithm.
 
 * Extensions
 
 
 * 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
 
 ** $-1
 We should find a means to provide an access to values deep in the
 stack.  For instance, instead of
 

-       baz: qux { $$ = $<foo>-1 + $<bar>0 + $1; }
+        baz: qux { $$ = $<foo>-1 + $<bar>0 + $1; }

 
 we should be able to have:
 
 
 we should be able to have:
 


@@ -284,13 +215,13 @@ XML output for GNU Bison
 * Unit rules
 Maybe we could expand unit rules, i.e., transform
 
 * Unit rules
 Maybe we could expand unit rules, i.e., transform
 

-       exp: arith | bool;
-       arith: exp '+' exp;
-       bool: exp '&' exp;
+        exp: arith | bool;
+        arith: exp '+' exp;
+        bool: exp '&' exp;

 
 into
 
 
 into
 

-       exp: exp '+' exp | exp '&' exp;
+        exp: exp '+' exp | exp '&' exp;

 
 when there are no actions.  This can significantly speed up some
 grammars.  I can't find the papers.  In particular the book `LR
 
 when there are no actions.  This can significantly speed up some
 grammars.  I can't find the papers.  In particular the book `LR


@@ -315,19 +246,19 @@ Wow, %printer is not documented.  Clearly mark YYPRINT as obsolete.
 * Coding system independence
 Paul notes:
 
 * Coding system independence
 Paul notes:
 

-       Currently Bison assumes 8-bit bytes (i.e. that UCHAR_MAX is
-       255).  It also assumes that the 8-bit character encoding is
-       the same for the invocation of 'bison' as it is for the
-       invocation of 'cc', but this is not necessarily true when
-       people run bison on an ASCII host and then use cc on an EBCDIC
-       host.  I don't think these topics are worth our time
-       addressing (unless we find a gung-ho volunteer for EBCDIC or
-       PDP-10 ports :-) but they should probably be documented
-       somewhere.
+        Currently Bison assumes 8-bit bytes (i.e. that UCHAR_MAX is
+        255).  It also assumes that the 8-bit character encoding is
+        the same for the invocation of 'bison' as it is for the
+        invocation of 'cc', but this is not necessarily true when
+        people run bison on an ASCII host and then use cc on an EBCDIC
+        host.  I don't think these topics are worth our time
+        addressing (unless we find a gung-ho volunteer for EBCDIC or
+        PDP-10 ports :-) but they should probably be documented
+        somewhere.

 
 

-       More importantly, Bison does not currently allow NUL bytes in
-       tokens, either via escapes (e.g., "x\0y") or via a NUL byte in
-       the source code.  This should get fixed.
+        More importantly, Bison does not currently allow NUL bytes in
+        tokens, either via escapes (e.g., "x\0y") or via a NUL byte in
+        the source code.  This should get fixed.

 
 * --graph
 Show reductions.
 
 * --graph
 Show reductions.


@@ -426,10 +357,32 @@ to bison. If you're interested, I'll work on a patch.
 * Better graphics
 Equip the parser with a means to create the (visual) parse tree.
 
 * Better graphics
 Equip the parser with a means to create the (visual) parse tree.
 

+* Complaint submessage indentation.
+We already have an implementation that works fairly well for named
+reference messages, but it would be nice to use it consistently for all
+submessages from Bison.  For example, the "previous definition"
+submessage or the list of correct values for a %define variable might
+look better with indentation.
+
+However, the current implementation makes the assumption that the
+location printed on the first line is not usually much shorter than the
+locations printed on the submessage lines that follow.  That assumption
+may not hold true as often for some kinds of submessages especially if
+we ever support multiple grammar files.
+
+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:
+

 -----
 
 -----
 

-Copyright (C) 2001, 2002, 2003, 2004, 2006, 2008 Free Software Foundation,
-Inc.
+Copyright (C) 2001-2004, 2006, 2008-2012 Free Software Foundation, Inc.

 
 This file is part of Bison, the GNU Compiler Compiler.
 
 
 This file is part of Bison, the GNU Compiler Compiler.