Class: Parser

Inherits:
Object show all
Includes:
Environment, ErrorMessages, Printer, Validator
Defined in:
lib/lisp/interpreter/parser.rb

Overview

Parser is used to validate the user input and parse it to the tokenizer

Constant Summary

Constants included from Environment

Environment::PROD, Environment::TEST

Instance Method Summary collapse

Methods included from Printer

#display_result, #finalize_result, #find_result_type, #format_result

Methods included from Validator

#balanced_brackets?, #balanced_quotes?, #valid_function, #valid_var, #valid_var_name

Methods included from ErrorMessages

#arg_err_build, #no_procedure_build, #type_err, #unbalanced_brackets_error, #unbalanced_quotes_error, #unbound_symbol_err

Constructor Details

#initialize(env_type = Environment::TEST) ⇒ Parser

Returns a new instance of Parser.



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# File 'lib/lisp/interpreter/parser.rb', line 17

def initialize(env_type = Environment::TEST)
  @env_type = env_type
  @tokenizer = Tokenizer.new
end

Instance Method Details

#parse(token) ⇒ Object 



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# File 'lib/lisp/interpreter/parser.rb', line 44

def parse(token)
  return read_file token if (token.start_with? 'ghci') && token.size > 4
  token_error = validate_token token
  result =
    if token_error.nil?
      @tokenizer.tokenize split_token token
    else
      token_error
    end
  finalize_result result unless result.to_s.empty?
end

#read_file(token) ⇒ Object 



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# File 'lib/lisp/interpreter/parser.rb', line 94

def read_file(token)
  res = read_file_helper token
  return finalize_result res if res.is_a? String
  filename = token[5..-1]
  return read_file_executor filename if File.exist? filename
  finalize_result 'File with name "' + filename + '" does not exist!'
end

#read_file_execute_lines(f, expr) ⇒ Object 



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# File 'lib/lisp/interpreter/parser.rb', line 76

def read_file_execute_lines(f, expr)
  last_value = ''
  f.each do |line|
    expr << line
    if (validate_token expr).nil? && expr != ''
      last_value = parse expr
      expr = ''
    end
  end
  last_value
end

#read_file_executor(file) ⇒ Object 



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# File 'lib/lisp/interpreter/parser.rb', line 88

def read_file_executor(file)
  f = File.open(file)
  expr = ''
  read_file_execute_lines f, expr
end

#read_file_helper(token) ⇒ Object 



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# File 'lib/lisp/interpreter/parser.rb', line 68

def read_file_helper(token)
  pattern = /^ghci .*\.[.ss|.scm]+$/
  result = (token =~ pattern)
  return unless result.nil?
  token = token[5..-1].nil? ? token[4..-1] : token[5..-1]
  'File with name "' + token.to_s + '" is not valid scheme file'
end

#read_input(token) ⇒ Object 



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# File 'lib/lisp/interpreter/parser.rb', line 35

def read_input(token)
  until (validate_token token).nil? && token != ''
    crr_input = STDIN.gets.chomp
    token << crr_input
    break if crr_input == ''
  end
  token
end

#run ⇒ Object 



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# File 'lib/lisp/interpreter/parser.rb', line 22

def run
  loop do
    print 'zakichan> ' if @env_type == Environment::PROD
    begin
      token = read_input('')
    rescue Interrupt
      puts 'Exiting..!'
      sleep(1)
    end
    parse token
  end
end

#split_token(token) ⇒ Object 



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# File 'lib/lisp/interpreter/parser.rb', line 56

def split_token(token)
  result = []
  token.split(/\s+(?=(?:[^"]*"[^"]*")*[^"]*$)/).each do |t|
    if !t.string? && (t.include?('(') || t.include?(')'))
      t.to_s.split(/(\(|\))/).each { |p| result << p }
    else
      result << t
    end
  end
  result
end

#validate_token(token) ⇒ Object 



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# File 'lib/lisp/interpreter/parser.rb', line 102

def validate_token(token)
  if !balanced_brackets? token
    unbalanced_brackets_error
  elsif !balanced_quotes? token
    unbalanced_quotes_error
  end
end