my $data = qq[
  this is some text.
  A period (".") usually terminates a statement.
  But not if it is quoted.
  Regardless of whether or not single quotes, '.', are used.
  And yes, "Mr. Ovid," even lines with a period in the middle of a quote.
];

my $doublequoted = qr/"[^"\\]*(?:\\.[^"\\]*)*"/m;
my $singlequoted = qr/'[^'\\]*(?:\\.[^'\\]*)*'/m;
my $sentence     = qr/ (?: $singlequoted | $doublequoted | [^.] )* \. /xm;

my @items = $data =~ /($sentence)/g;

print "[$_]\n" for @items;

##</code><code>##

my $float        = qr/\d+\.\d+/;
my $sentence     = qr/ (?: $float | $singlequoted | $doublequoted | [^.] )+ \. /xm;

$data .= "g = 9.8 m/s.";