use strict;

# make up some data
my $line = "('The text.')-- 5 o'clock! What's cookin' with the text data?";

# split on whitespace, keep only tokens that contain at least on letter
my @words = grep /\p{L}/i, split ' ', $line;

my %wcount;
for ( @words ) {  # using $_ will modify @words "in-place"
    s/^\P{L}+//;  # remove initial non-letters
    s/\P{L}+$//;  # remove final non-letters
    $wcount{lc()}++;  # normalize to lower-case-only
}

print "$wcount{$_}\t$_\n" for ( sort keys %wcount );

__OUTPUT__
1       cookin
1       data
1       o'clock
2       text
2       the
1       what's
1       with