Class: Parser

Inherits:
Object show all
Includes:
Environment, ErrorMessages, 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 Validator

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

Methods included from ErrorMessages

#unbalanced_brackets_error, #unbalanced_quotes_error

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

#fetch_file_read(token) ⇒ Object 



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

def fetch_file_read(token)
  res = read_file token
  print_result res unless res.to_s.empty?
end

#parse(token) ⇒ Object 



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# File 'lib/lisp/interpreter/parser.rb', line 93

def parse(token)
  return fetch_file_read token if token.start_with? 'ghci'
  token_error = validate_token token
  result =
    if token_error.nil?
      @tokenizer.tokenize split_token token
    else
      token_error
    end
  print_result result unless result.to_s.empty?
end

#print_result(result) ⇒ Object 



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# File 'lib/lisp/interpreter/parser.rb', line 113

def print_result(result)
  to_remove = result.to_s.list? || result.to_s.pair? || result.to_s.quote?
  result = result.delete('\'') if to_remove
  puts result if @env_type == Environment::PROD
  result
end

#read_file(token) ⇒ Object 



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# File 'lib/lisp/interpreter/parser.rb', line 77

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

#read_file_executor(file) ⇒ Object 



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# File 'lib/lisp/interpreter/parser.rb', line 70

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

#read_file_helper(token) ⇒ Object 



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# File 'lib/lisp/interpreter/parser.rb', line 47

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

#read_file_reader(f, value, expr) ⇒ Object 



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# File 'lib/lisp/interpreter/parser.rb', line 59

def read_file_reader(f, value, expr)
  while (c = f.read(1))
    expr << c
    if (validate_token expr).nil? && expr != ''
      last_value = parse expr
      expr = ''
    end
  end
  last_value
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
    token = ''
    until (validate_token token).nil? && token != ''
      crr_input = STDIN.gets.chomp
      token << crr_input
      break if crr_input == ''
    end
    parse token
  end
end

#split_token(token) ⇒ Object 



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

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 105

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