Thumbtack programming challenge - Simple Database in Ruby before transactional block support

database_step1.rb

class SimpleDatabase
 
  attr_accessor :database
 
  def initialize
    @database = {} #our database!
  end
 
  def set(name, value)
  database[name] = value #write the new value to the database
  end
 
  def get(name)
   if database[name]
    puts database[name] #return the saved value
   else puts 'NULL' #unless there is no value there
   end
  end
 
  def unset(name)
    database.delete(name) #delete the current value in the database
  end
	
  def numequalto(value)
    puts database.values.count(value) #count how many pairs have the value
  end
 
  def evaluate_data_command(input)
    command = input.split(' ')
    valid = ["SET", "GET", "UNSET", "NUMEQUALTO"]
    abort() if command[0] == "END"
    if valid.include?(command[0])
      case command[0]
      when "SET"
        set(command[1], command[2])
      when "GET"
        get(command[1])
      when "UNSET"
        unset(command[1])
      when "NUMEQUALTO"
        numequalto(command[1])
      end
    else
      puts "NO METHOD FOUND"
    end
  end
end
 
db = SimpleDatabase.new
 
STDIN.each_line do |l|
  db.evaluate_data_command(l)
end