Compilers - Recursive Predictive Parser in Ruby

recursive_asd.rb

#!/usr/bin/env ruby
 
require 'pry'
require 'terminal-table'
 
DELIM = '$'
 
def get_next_token(input)
  @token = input[@counter]
  @counter += 1
end
 
def raise_error_msg()
  raise "ERRO"
end
 
def raise_success_msg()
  @rows << [@formated_input, "SUCESSO"]
end
 
def analyze_string(input)
  get_next_token(input)
 
  if @token === 'x'
   get_next_token(input)
  elsif @token === '('
    loop do
      # reconhecer soma
      analyze_string(input)
      break if @token != '+'
    end
 
    if @token === ')'
      get_next_token(input)
    else
      raise_error_msg()
    end
  else
    raise_error_msg()
  end
end
 
def check_final_token()
  if @token === DELIM
    raise_success_msg()
  else
    raise_error_msg()
  end
end
 
def add_final_token(tokens_array, character)
  tokens_array.push(character)
end
 
def extract_tokens(input)
  temp = input.scan(/[\w+,'+','(',')']/)
  temp = add_final_token(temp, DELIM)
  return temp
end
 
def setup
  @counter = 0
  @input_array = []
 
  if(ARGV.length > 0)
    file = File.new ARGV[0], "r"
    while line = file.gets
      @input_array.push(extract_tokens(line))
    end
  else
    print "Digite cadeia a ser analisada: "
    input_string = gets.chomp
    @input_array.push(extract_tokens(input_string))
  end
end
 
def create_table()
  table =  Terminal::Table.new title: "ASD Preditiva Recursiva", headings: [{value: 'CADEIA', alignment: :center},{value: 'STATUS', alignment: :center}], rows: @rows
  table.align_column(0, :right)
  return table
end
 
def main
  @alphabet = ["(", ")", "x", "+"]
  # initialize table container
  @rows = []
  setup()
  # binding.pry
  @input_array.each do |input|
    begin
      @formated_input = ""
      input.each {|l| @formated_input += l unless l === '$'}
      @counter = 0
      analyze_string(input)
      check_final_token()
    rescue RuntimeError => e
      @rows << [@formated_input, e.message]
    end
  end
  table = create_table()
  puts table
end
 
main()