my $current_line = q{};
while( defined( my $line = <> ) ) {
  chomp( $line );

  if( $line =~ m{^ \s+ \w+ }x ) {
    $current_line .= $line;
    next;
  } else {
    _process_line( $current_line );
    $current_line = $line;
  }
}

if( $current_line ) {
  _process_line( $current_line );
}

sub _process_line {
  my( $line ) = $shift;
  ## do whatever . . .
}

##</code><code>##

#!/usr/bin/env perl
use 5.018;
use JSON::XS qw( encode_json );

my $current_line = q{};
while ( defined( my $line = <DATA> ) ) {
    chomp($line);

    if ( $line =~ m{^ \s+ \w+ }x ) {
        $current_line .= $line;
        next;
    } else {
        if ($current_line) {
            _process_line($current_line);
        }
        $current_line = $line;
    }
}
if ($current_line) {
    _process_line($current_line);
}

sub _process_line {
    my ($line) = shift;
    my ( $kwd, @vals ) = split( /\s+/, $line );

    say qq{keyword '$kwd' has }, scalar @vals, qq{ values: },
        encode_json( \@vals );
}

exit 0;

__END__
keyword1 data1 data2 data3
keyword2 data1 data2 data3
    data4 data5
    data6
keyword1 data1 data2 data3 data4
keyword3 data1

##</code><code>##

~ $ perl $_
keyword 'keyword1' has 3 values: ["data1","data2","data3"]
keyword 'keyword2' has 6 values: ["data1","data2","data3","data4","data5","data6"]
keyword 'keyword1' has 4 values: ["data1","data2","data3","data4"]
keyword 'keyword3' has 1 values: ["data1"]