[src/trunk]: src/usr.bin/config Write out the expression grammar for dependen...

[dholland <dholland%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/c37863df7b8a
branches:  trunk
changeset: 777965:c37863df7b8a
user:      dholland <dholland%NetBSD.org@localhost>
date:      Sun Mar 11 02:56:25 2012 +0000

description:
Write out the expression grammar for dependency constraints instead of
using precedence rules. Precedence rules (besides being a hack) often
lead to unexpected/unwanted behavior in corner cases.

diffstat:

 usr.bin/config/gram.y |  29 ++++++++++++++++++++++-------
 1 files changed, 22 insertions(+), 7 deletions(-)

diffs (55 lines):

diff -r 8e78dec1b581 -r c37863df7b8a usr.bin/config/gram.y
--- a/usr.bin/config/gram.y     Sun Mar 11 02:43:33 2012 +0000
+++ b/usr.bin/config/gram.y     Sun Mar 11 02:56:25 2012 +0000
@@ -1,5 +1,5 @@
 %{
-/*     $NetBSD: gram.y,v 1.29 2012/03/11 02:43:33 dholland Exp $       */
+/*     $NetBSD: gram.y,v 1.30 2012/03/11 02:56:25 dholland Exp $       */
 
 /*
  * Copyright (c) 1992, 1993
@@ -123,10 +123,8 @@
 %token <str> PATHNAME QSTRING WORD EMPTYSTRING
 %token ENDDEFS
 
-%left '|'
-%left '&'
-
 %type  <list>  fopts fexpr fatom
+%type  <list>  f_or_expr f_and_expr f_prefix_expr f_base_expr
 %type  <str>   fs_spec
 %type  <val>   fflgs fflag oflgs oflag
 %type  <str>   rule
@@ -755,12 +753,29 @@
  */
 
 /* expression of config elements */
-/* XXX this should use a real expression grammar */
 fexpr:
+       f_or_expr
+;
+
+f_or_expr:
+         f_and_expr
+       | f_or_expr '|' f_and_expr      { $$ = fx_or($1, $3); }
+;
+
+f_and_expr:
+         f_prefix_expr
+       | f_and_expr '&' f_prefix_expr  { $$ = fx_and($1, $3); }
+;
+
+f_prefix_expr:
+         f_base_expr
+/* XXX notyet - need to strengthen downstream first */
+/*     | '!' f_prefix_expr             { $$ = fx_not($2); } */
+;
+
+f_base_expr:
          fatom                         { $$ = $1; }
        | '!' fatom                     { $$ = fx_not($2); }
-       | fexpr '&' fexpr               { $$ = fx_and($1, $3); }
-       | fexpr '|' fexpr               { $$ = fx_or($1, $3); }
        | '(' fexpr ')'                 { $$ = $2; }
 ;