read_line_group

gistfile1.pl

#!perl -w
use strict;
use warnings;
use IO::Unread 'unread';
use Data::Dumper;

sub read_line_group {
  my ($handle, $key_regex) = @_;
  my $previous_key;
  my @lines;
  while (<>) {
    my ($current_key) = $_ =~ $key_regex;
    if (defined $previous_key and $previous_key ne $current_key) {
      unread($handle, $_);
      last;
    }
    push @lines, $_;
    $previous_key //= $current_key;
  }
  return @lines;
}

# read two blocks
print Dumper [ read_line_group \*STDIN, qr/^(\S+)/ ];
print Dumper [ read_line_group \*STDIN, qr/^(\S+)/ ];