--- ConditionalPlugin.pm.orig	2002-08-11 12:24:03.000000000 -0400
+++ ConditionalPlugin.pm	2003-01-24 21:42:38.000000000 -0500
@@ -38,10 +38,13 @@
 # =========================
 package TWiki::Plugins::ConditionalPlugin;
 
 # =========================
+use strict;
 use vars qw(
-         $VERSION $debug $sandbox $pluginInitialized
+         $VERSION $debug $sandbox $pluginInitialized $prefixPattern $ops
+	 $condPattern_ifonly $condPattern_ifelse $postfixPattern $topic $web
+	 $user $installWeb
     );
 
 #use Safe;
 
@@ -111,16 +114,32 @@
 	return;
     }
     
     _initDefaults() if( ! $pluginInitialized );
-
-    # try to match if/else first (otherwise it gets masked by the if-only 
-    # variant
-    $_[0] =~ s/$prefixPattern$condPattern_ifelse$postfixPattern/&handleConditional($3, $5, $6)/geo;
-
-    # try to match the if-only variant
-    $_[0] =~ s/$prefixPattern$condPattern_ifonly$postfixPattern/&handleConditional($3, $5, '')/geos;
-
+    
+    # Nested if support - find the last occurence of %IF each time through and
+    # process it first. Thus, the deepest nesting in each set of ifs is
+    # processed first and parsed correctly. -- Walter Mundt
+    
+    my $text = \$_[0];
+    my $ifIndex = rindex($$text, "%IF");
+    while ($ifIndex != -1) {
+	my $startText = substr($$text, 0, $ifIndex);
+	my $endText = substr($$text, $ifIndex);
+	
+	# try to match if/else first (otherwise it gets masked by the if-only 
+	# variant
+	$endText =~ s/$prefixPattern$condPattern_ifelse$postfixPattern/&handleConditional($3, $5, $6)/geos;
+    
+	# then try to match the if-only variant
+	$endText =~ s/$prefixPattern$condPattern_ifonly$postfixPattern/&handleConditional($3, $5, '')/geos;
+	
+	# mark any remaining %IFs as invalid syntax
+	$endText =~ s/^%IF/!!IF/s;
+	
+	$$text = $startText . $endText;
+	$ifIndex = rindex($$text, "%IF");
+    }
 }
 
 # =========================
 sub DISABLE_startRenderingHandler