in reply to Re^2: Manually incrementing @ array during for
in thread Manually incrementing @ array during for

Very similar approach in that case, just instead of reading lines from the file you walk the indexen instead. The concatenation and processing of entries is similar otherwise (my sample changes only 4 lines). 

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

my @lines = <DATA>;

my $current_line = q{};
my $idx          = 0;
while ( $idx <= $#lines ) {
    my $line = $lines[$idx];
    chomp($line);

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

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Re^4: Manually incrementing @ array during for
by AnomalousMonk (Archbishop) on Mar 16, 2020 at 20:20 UTC

    Note that the body of this while-loop is equally well suited to the original for-loop implementation. The array is not changed. 

    c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le
"my @ra = (
   'keyword1 data1 data2 data3',
   'keyword2 data1 data2 data3',
   '    data4 data5',
   '    data6',
   'keyword1 data1 data2 data3 data4',
   'keyword3 data1',
   );
 ;;
 my $rx_continuation = qr{ \A \s+ \w }xms;
 ;;
 my $current_line;
 LINE:
 for my $line (@ra) {
   if ($line =~ $rx_continuation) {
     $current_line .= $line;
     next LINE;
     }
   ;;
   _process($current_line) if $current_line;
   $current_line = $line;
   }
 ;;
 _process($current_line) if $current_line;
 ;;
 dd \@ra
 ;;
 ;;
 sub _process {
   print qq{'$_[0]' ->}, map qq{ '$_'}, split ' ', $_[0];
   }
"
'keyword1 data1 data2 data3' -> 'keyword1' 'data1' 'data2' 'data3'
'keyword2 data1 data2 data3    data4 data5    data6' -> 'keyword2' 'da
+ta1' 'data2' 'data3' 'data4' 'data5' 'data6'
'keyword1 data1 data2 data3 data4' -> 'keyword1' 'data1' 'data2' 'data
+3' 'data4'
'keyword3 data1' -> 'keyword3' 'data1'
[
  "keyword1 data1 data2 data3",
  "keyword2 data1 data2 data3",
  "    data4 data5",
  "    data6",
  "keyword1 data1 data2 data3 data4",
  "keyword3 data1",
]

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