#use strict;
use Regexp::Common qw /balanced/;

my $file = <<END;
* Converting valif() 
v1 0 1 pwl 0 -5 10n 5
e2 2 0 value=valif(v(1)>0, 2, -2)
.tran 10n 10n
.plot tran v(1) v(2)
END

#my %RE;
my @file = split('\n',$file);
my $re_valif=${RE}{balanced}{-keep}{-parens=>'()'};
print $re_valif . "\n";
foreach (@file) {
	print $_ . "\n";
	/${RE}{balanced}{-parens=>'()'}/ and print "->Matched |$1|$2|$3|$4|\n";
}