.pl

use utf8;
use Unicode::Normalize;

# Expand horizontal Kana iteration marks
# 例: いすゞ→いすず  ところゞゝゝ→ところどころ
sub expand_kanaiter {
  local $_ = NFKD($_[0]);
  s{(
    [あ-んア-ンー][\x{3099}\x{309a}]?
    (|(?1))
    [ゝヽ][\x{3099}\x{309a}]?
  )}{
    local $_ = $1;
    pos = $-[3]
    while s/
    \G([あ-んア-ンー])
      ([\x{3099}\x{309a}]?)
      ([^ゝヽ]*)[ゝヽ]
      ([\x{3099}\x{309a}]?)
    /$1$2$3$1$4/x;
    $_
  }xge;
  NFC($_);
}