+sub process_compare {
+ my ($lval, $cmp, $rval) = @_;
+
+ # remove whitespace
+
+ $lval =~ s/^\s*//;
+ $lval =~ s/\s*$//;
+
+ $rval =~ s/^\s*//;
+ $rval =~ s/\s*$//;
+
+ if ($cmp eq "==") {
+ return $lval eq $rval;
+ } elsif ($cmp eq "!=") {
+ return $lval ne $rval;
+ }
+
+ my $statement = "$lval $cmp $rval";
+ my $ret = eval $statement;
+
+ # $@ stores error of eval
+ if ($@) {
+ return -1;
+ }
+
+ return $ret;
+}
+
+sub value_defined {
+ my ($val) = @_;
+
+ return defined($variable{$2}) ||
+ defined($opt{$2});
+}
+
+my $d = 0;
+sub process_expression {
+ my ($name, $val) = @_;
+
+ my $c = $d++;
+
+ while ($val =~ s/\(([^\(]*?)\)/\&\&\&\&VAL\&\&\&\&/) {
+ my $express = $1;
+
+ if (process_expression($name, $express)) {
+ $val =~ s/\&\&\&\&VAL\&\&\&\&/ 1 /;
+ } else {
+ $val =~ s/\&\&\&\&VAL\&\&\&\&/ 0 /;
+ }
+ }
+
+ $d--;
+ my $OR = "\\|\\|";
+ my $AND = "\\&\\&";
+
+ while ($val =~ s/^(.*?)($OR|$AND)//) {
+ my $express = $1;
+ my $op = $2;
+
+ if (process_expression($name, $express)) {
+ if ($op eq "||") {
+ return 1;
+ }
+ } else {
+ if ($op eq "&&") {
+ return 0;
+ }
+ }
+ }
+
+ if ($val =~ /(.*)(==|\!=|>=|<=|>|<)(.*)/) {
+ my $ret = process_compare($1, $2, $3);
+ if ($ret < 0) {
+ die "$name: $.: Unable to process comparison\n";
+ }
+ return $ret;
+ }
+
+ if ($val =~ /^\s*(NOT\s*)?DEFINED\s+(\S+)\s*$/) {
+ if (defined $1) {
+ return !value_defined($2);
+ } else {
+ return value_defined($2);
+ }
+ }
+
+ if ($val =~ /^\s*0\s*$/) {
+ return 0;
+ } elsif ($val =~ /^\s*\d+\s*$/) {
+ return 1;
+ }
+
+ die ("$name: $.: Undefined content $val in if statement\n");
+}
+
+sub process_if {
+ my ($name, $value) = @_;
+
+ # Convert variables and replace undefined ones with 0
+ my $val = process_variables($value, 1);
+ my $ret = process_expression $name, $val;
+
+ return $ret;
+}