How to study rgss3 elegantly (1) Suffix automation implemented by ruby

* I really don't know Ruby *

#encoding: utf-8
# ====================================================== =============================
# ■ Suffix_Automaton
# ------------------------------------------------- -----------------------------
# Suffix automaton.
# ====================================================== ===============================

class Suffix_Automaton
  # ------------------------------------------------- -------------------------
  # ● Define instance variables
  # ------------------------------------------------- -------------------------
  attr_reader: total # number of different substrings in current SAM
  attr_reader: root # root node of SAM
  # ====================================================== =============================
  # ■ State
  # ------------------------------------------------- -----------------------------
  # Suffix automata status node.
  # ================================================= =============================
  class State
    # ------------------------------------------------- -------------------------
    # ● Define instance variables
    # ------------------------------------------------- -------------------------
    attr_accessor: par # parent
    attr_accessor: go # go
    attr_accessor: val # val
    # ------------------------------------------------- -------------------------
    # ● Initialization status node
    # ------------------------------------------------- -------------------------
    def init (val = 0)
      @par = nil
      @go = []
      @val = val
      for i in 0..26 do
        @go [i] = nil
      end
    end
    # ------------------------------------------------- -------------------------
    # ● Calculate the number of different substrings represented by the node
    # ------------------------------------------------- -------------------------
    def calc
      return 0 if @par == nil
      return @val-@ par.val
    end
  end
  # ------------------------------------------------- -------------------------
  # ● Initialize the suffix automaton
  # ------------------------------------------------- -------------------------
  def initSAM
    @total = 0
    @cur = 0
    @nodePool = []
    @root = newState
    @last = @root
  end
  # ------------------------------------------------- -------------------------
  # ● Create a new status node
  # ------------------------------------------------- -------------------------
  def newState (val = 0)
    @nodePool [@cur] = State.new
    @nodePool [@cur] .init (val)
    @cur + = 1
    return @nodePool [@ cur-1]
  end
  # ------------------------------------------------- -------------------------
  # ● Add characters
  # ------------------------------------------------- -------------------------
  def extend (w)
    p = @last
    np = newState (p.val + 1)
    while p! = nil and p.go [w] == nil do
      p.go [w] = np
      p = p.par
    end
    if p == nil
      np.par = @root
      @total + = np.calc # statistics
    else
      q = p.go [w]
      if p.val + 1 == q.val
        np.par = q
        @total + = np.calc # Statistics
      else
        nq = newState (p.val + 1)
        for i in 0..26 do
          nq.go [i] = q.go [i]
        end
        @total-= q.calc # Statistics
        nq.par = q.par
        q.par = nq
        np.par = nq
        @total + = q.calc + nq.calc + np.calc
        while p! = nil and p.go [w] == q do
          p.go [w] = nq
          p = p.par
        end
      end
    end
    @last = np
  end
end