##############################################################
#
# This function removes single instances of whitespace and
# converts multiple adjacent whitespace characters to a single
# space. In this function, "whitespace" is defined as a character
# whose ASCII value is less than 33. (This includes many special
# characters such as new line characters, nul, bel, etc.)
#
#   Usage: STRING = CollapseWhitespace(STRING)
#
#   Example:
#     CollapseWhitespace("\n\t abc 123   xxx\n") --> " abc123 xxx"
#
sub CollapseWhitespace
{
  @_ or return '';
  my $T = shift;
  defined $T or return '';
  my $L = length($T);
  $L or return ''; 

  my $c;
  my $N = 0;	# consecutive whitespace counter
  my $P = 0;	# target pointer to overwrite original str $T
  my $U = 1;	# string length will be left unchanged
  for (my $i = 0; $i < $L; $i++)
  {
    $c = vec($T, $i, 8);
    if ($c < 33)
    {
      $U = 0;
      if ($N++ == 1) { vec($T, $P++, 8) = 32; }
    }
    else
    {
      $N = 0;
      $U or vec($T, $P, 8) = $c;
      $P++;
    }
  }
  return $U ? $T : substr($T, 0, $P);
}