Module: IdStuffer

Defined in:
lib/id_stuffer.rb

Constant Summary collapse

PREFIX = 
'IdS'

Class Method Summary collapse

Class Method Details

.stuff(list) ⇒ Object

compress the list of ids as good as I could imagine ;) uses fancy base twisting



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# File 'lib/id_stuffer.rb', line 7

def self.stuff(list)
  return PREFIX if list.length == 0
  PREFIX.dup << (list.sort.uniq.map(&:to_i).inject([[-9,-9]]) do |l, c|
    if l.last.last+1 == c
      l.last[-1] = c
      l
    else
      l << [c,c]
    end
  end.map do |r|
    if r.first == r.last
      r.first.to_s(8)
    else
      r.first.to_s(8) << "8" << r.last.to_s(8)
    end
  end[1..-1].join("9").to_i.to_s(36))
end

.unstuff(str) ⇒ Object

inverse of compress_id_list



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# File 'lib/id_stuffer.rb', line 26

def self.unstuff(str)
  return [] if !str or str.length==0 or str=='0' or str==PREFIX
  raise "Corrupted id list. Starts w/o mandatory prefix" unless str.start_with?(PREFIX)
  n = str[PREFIX.length..-1].to_i(36).to_s.split("9").map do |e|
    p = e.split("8")
    if p.length == 1 then p[0].to_i(8)
    elsif p.length == 2 then (p[0].to_i(8)..p[1].to_i(8)).entries
    else raise "Corrupted id list. Or a bug ;)"
    end
  end.flatten
end