Markov algorithm interpreter

markov.rb

# -*- coding: utf-8 -*-
Rule = Struct.new :from, :to, :exit

def parseSingleRule(rule_src)
  rule_src =~ /^\s*([^\s]*)\s*=>\s*([\.]?)([^\s]*)\s*$/
  r = Rule.new($1, $3)
  r.exit = $2 == '.'
  r
end

def parseMultipleRules(rules_src)
  rules_src.split("\n").map{|x| parseSingleRule x}
end

def applyRules(rules, str, options={})
  exit = false
  verbose = options[:verbose]
  puts str if verbose
  loop do
    found_rule = false
    rules.each do |rule|
      if str.index(rule.from)
        str.sub!(rule.from, rule.to)
        found_rule = true
        if verbose then
          puts "applying rule #{rule.from} => #{rule.to}:\t#{str}"
        end
        exit = rule.exit
        break
      end
    end
    break if exit or not found_rule
  end
  str
end

min = <<MIN
$| => |$
|*| => *$
*| => *
β| => β
β* => β
β$ => |β
β => .
=> β
MIN

rules = parseMultipleRules min
puts applyRules(rules, "|||||*|||", verbose: true)