Renamed from "Invalid \$n", to work around an Autoconf bug with dollar

[bison.git] / TODO

diff --git a/TODO b/TODO
index 7b4b7fd420bb3a998afec3b544308ee03493b4f9..3b2bf6905efb7da2e566cdd874ea01b73c551a1f 100644 (file)
--- a/TODO
+++ b/TODO
@@ -17,8 +17,8 @@ Write a first documentation for C++ output.
 
 
 * Documentation
-Before releasing, make sure the documentation refers to the current
-`output' format.
+Before releasing, make sure the documentation ("Understanding your
+parser") refers to the current `output' format.
 
 
 * GLR & C++
@@ -29,7 +29,7 @@ Currently, the GLR parser cannot compile with a C++ compiler.
 
 **  GLR
 How would Paul like to display the conflicted actions?  In particular,
-what when two reductions are possible on a given lookahead, but one is
+what when two reductions are possible on a given look-ahead token, but one is
 part of $default.  Should we make the two reductions explicit, or just
 keep $default?  See the following point.
 
@@ -52,10 +52,39 @@ DeRemer and Penello: they already provide the algorithm.
 
 * Extensions
 
-** yyerror, yysymprint interface
+** %destructor
+I think we should document it as experimental, and allow its use in
+the next releases.  But we also need to port it to GLR.  What about
+lalr1.cc?  Well, read what Hans reported, maybe we don't want
+%detructor.  On the other hand, there is no reason not to provide it:
+users can avoid its use.
+
+** $foo
+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...
+
+** $-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 + $1; }
+
+we should be able to have:
+
+  foo($foo) bar($bar) baz($bar): qux($qux) { $baz = $foo + $bar + $qux; }
+
+Or something like this.
+
+** yysymprint 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...
+locations, and YYPARSE_PARAMS.  For the time being, it is almost
+recommended to yyprint to steal internal variables...
 
 ** Several %unions
 I think this is a pleasant (but useless currently) feature, but in the
@@ -88,6 +117,20 @@ to avoid falling into another CPP mistake.
 ** -D, --define-muscle NAME=VALUE
 To define muscles via cli.  Or maybe support directly NAME=VALUE?
 
+** XML Output
+There are couple of available extensions of Bison targeting some XML
+output.  Some day we should consider including them.  One issue is
+that they seem to be quite orthogonal to the parsing technique, and
+seem to depend mostly on the possibility to have some code triggered
+for each reduction.  As a matter of fact, such hooks could also be
+used to generate the yydebug traces.  Some generic scheme probably
+exists in there.
+
+XML output for GNU Bison and gcc
+   http://www.cs.may.ie/~jpower/Research/bisonXML/
+
+XML output for GNU Bison
+   http://yaxx.sourceforge.net/
 
 * Unit rules
 Maybe we could expand unit rules, i.e., transform
@@ -131,7 +174,7 @@ There are a couple of proposed outputs:
   which is based on Bison.
   <http://www.goice.co.jp/member/mo/hack-progs/bison-java.html>
 
-Sébastien Serrurier (serrur_s@epita.fr) is working on this: he is
+Sebastien Serrurier (serrur_s@epita.fr) is working on this: he is
 expected to contact the authors, design the output, and implement it
 into Bison.
 
@@ -149,7 +192,9 @@ Paul notes:
        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.
 
 * --graph
 Show reductions.       []
@@ -294,7 +339,7 @@ the parser with a means to create the (visual) parse tree.
 
 -----
 
-Copyright (C) 2001, 2002 Free Software Foundation, Inc.
+Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
 
 This file is part of GNU Bison.