#!/usr/bin/env ruby

require 'zipf'
require 'optimist'

conf = Optimist::options do
  banner "ng < <input>"
  opt :n, "n for Ngrams", :type => :int, :default => 4
  opt :fix, "Don't output lower order Ngrams.", :type => :bool, :default => false
  opt :separator, "separte ngrams of a line by this string", :type => :string, :default => "\n"
end

while line = STDIN.gets
  a = []
  ngrams(line, conf[:n], conf[:fix]) { |ng| a << ng.join(' ') }
  a.reject! { |i| i.strip.size==0 }
  puts a.join conf[:separator] if a.size>0
end