Just for the fun of it, here's a way which translates your text into XML, then uses XML::Simple on the result:
use strict;
use Data::Dumper;
use XML::Simple;
my $str = do { local $/=undef; <DATA> };
LOOP: {
for ($str) {
# Make start/end tags for current level
s#^(\w+)(.*?)(?=^[\w<]|\Z)#<$1>$2\n</$1>\n#smg;
# Process next level
s/^\t//mg or last LOOP;
}
redo LOOP;
}
my $xs = XML::Simple->new(suppressempty=>'');
# Add root element
my $href = $xs->XMLin("<root>$str</root>");
print Dumper($href);
__DATA__
abc
def
ghi
jkl
mno
pqr
