Class: Taoism::Console

Inherits:
Object
  • Object
show all
Defined in:
lib/taoism/console.rb

Constant Summary collapse

PS1 = 
'taoism:%03d> '
PS2 = 
'taoism:%03d* '

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Console

Returns a new instance of Console.



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# File 'lib/taoism/console.rb', line 6

def initialize
  @evaluator = Evaluator.new
  @line_no = 1
end

Instance Method Details

#evaluate(input) ⇒ Object 



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# File 'lib/taoism/console.rb', line 50

def evaluate(input)
  lexer = Lexer.new(input)
  parser = Parser.new(lexer)

  ast = parser.parse

  if parser.errors.empty?
    result = @evaluator.evaluate(ast)
    puts Runtime.repr(result)
  else
    parser.errors.each do |err|
      $stderr.puts "Error: #{err}"
    end
  end
rescue Runtime::Error, Runtime::Return, Runtime::Leave => err
  $stderr.puts "Error: #{err.message}"
end

#read_input ⇒ Object 



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# File 'lib/taoism/console.rb', line 23

def read_input
  ps1 = PS1 % @line_no
  ps2 = PS2 % @line_no

  input = Readline.readline(ps1, true)
  return if input.nil?
  input = input.chomp

  had_continuation = false

  while unclosed?(input)
    had_continuation = true
    line = Readline.readline(ps2, false)

    break unless line
    input << "\n" << line.chomp
  end

  if had_continuation
    Readline::HISTORY.pop
    Readline::HISTORY << input
  end

  @line_no += 1
  input
end

#run ⇒ Object 



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# File 'lib/taoism/console.rb', line 11

def run
  require 'readline'

  loop do
    input = read_input
    break unless input

    break if input.strip == 'exit'
    evaluate(input)
  end
end

#unclosed?(input) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/taoism/console.rb', line 68

def unclosed?(input)
  input.count('{') > input.count('}')
end