From daf489b1c9a3f4dc306c82bf330771540179a1bf Mon Sep 17 00:00:00 2001
From: Pavel Charvat <pavel.charvat@netcentrum.cz>
Date: Wed, 17 Jan 2007 01:20:56 +0100
Subject: [PATCH] Support for the following syntax in configuration files:

#if CONFIG_ABC || !CONFIG_DEF
#elsif (CONFIG_GHI && CONFIG_JKL) || CONFIG_MNO
#else
#endif

Alternatively I can cache it to C-like "defined(CONFIG_ABC)"
(CONFIG_ABC alone could expand to its value)
or to pure Perl code without substitutions.
---
 build/genconf | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/build/genconf b/build/genconf
index 0d7bc737..75c957fe 100755
--- a/build/genconf
+++ b/build/genconf
@@ -15,6 +15,9 @@ while (<CF>) {
 }
 close CF;
 
+my $opt_regex = join("|", keys %options);
+sub eval_expr { $_ = "@_"; s/\b($opt_regex)\b/ 1 /g if $opt_regex; s/\bCONFIG_\w+\b/ 0 /g; return eval $_; }
+
 open IN, $ARGV[0] or die "Unable to open $ARGV[0]";
 open OUT, ">$ARGV[1]" or die "Unable to create $ARGV[1]";
 my @ifs = ();	# stack of conditions, 1=satisfied, -1=unsatisfied, 0=shadowed
@@ -24,12 +27,18 @@ while (<IN>) {
 		push @ifs, (@ifs && $ifs[$#ifs] <= 0) ? 0 : (defined $options{$1}) ? 1 : -1;
 	} elsif (/^#ifndef\s+(\w+)/) {
 		push @ifs, (@ifs && $ifs[$#ifs] <= 0) ? 0 : (defined $options{$1}) ? -1 : 1;
+	} elsif (/^#if\s(.*)$/) {
+		push @ifs, (@ifs && $ifs[$#ifs] <= 0) ? 0 : (eval_expr $1) ? 1 : -1;
 	} elsif (/^#endif/) {
 		defined pop @ifs || die "Improper nesting of conditionals";
 	} elsif (/^#else/) {
 		my $x = pop @ifs;
 		defined $x || die "Improper nesting of conditionals";
-		push @ifs, -$x;
+		push @ifs, $x >= 0 ? 0 : 1;
+	} elsif (/^#elsif\s(.*)$/) {
+		my $x = pop @ifs;
+		defined $x || die "Improper nesting of conditionals";
+		push @ifs, $x >= 0 ? 0 : (eval_expr $1) ? 1 : -1;
 	} else {
 		@ifs && $ifs[$#ifs] <= 0 && next;
 		if (/^$/) {
-- 
2.39.2