I had a quick look at the code out of interest. The problem occurs in the str_normalize function. The code is buggy and it does not check boundary conditions properly.

Below is the line of the code that caused the problem.

if(isalpha(*(s-1)) && strchr(chrsep, *s) && isalpha(*(s+1))) {
  if(space_words(s, *s)) {
    char c = *s;
    while(*s) {
      if(*s == c) s++;
      else if(!isalpha(*s)) break;
      *p = *s;
      s++;
      p++;
    }
  }
}
[download]

The code detects a possible space character, and tries to validate it. But the single character 'I' and the spaces surrounding it caused logical malfunction in the space_words function. Thus <space> is not recognized as separator for the words.

My advise is to ditch this module, and use simple Perl implementation. The single line below does pretty much what the ExtractWords.xs code does in hundred lines of C.

#!/usr/bin/perl

use strict;
use warnings;
use Data::Dumper;

my @strings = (
  q|one two 'three' one|,
  q|yes i am 'sme'|,
  q|x21 y z|,
);

for my $str (@strings){
  my %hash;
  for ( map { length >= 3 ? $_ : () } $str =~ /(\w+)/g ) {
     $hash{$_}++;
  }
  print Dumper(\%hash);
}
[download]

And the output is

$VAR1 = {
          'three' => 1,
          'one' => 2,
          'two' => 1
        };
$VAR1 = {
          'yes' => 1,
          'sme' => 1
        };
$VAR1 = {
          'x21' => 1
        };
[download]

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