Module: GermanNumbers::StateMachine

Included in:
Parser::Parser, Parser::SmallNumberParser, Parser::StackMachine
Defined in:
lib/german_numbers/state_machine.rb

Defined Under Namespace

Classes: Machine, State, StateError

Instance Method Summary collapse

Instance Method Details

#state_machine_for(field, &block) ⇒ Object

rubocop:disable Metrics/AbcSize rubocop:disable Metrics/MethodLength



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# File 'lib/german_numbers/state_machine.rb', line 60

def state_machine_for(field, &block)
  m = Machine.new
  m.instance_eval(&block)
  var_name = "@#{field}_state"
  set_name = "#{field}_state="
  history_name = "@#{field}_state_history"

  define_method("#{field}_state") do
    instance_variable_get(var_name)
  end

  define_method(set_name) do |ns|
    state = instance_variable_get(var_name)
    raise StateError, "#{ns} is not possible state after #{state}" unless m.transitions[state].include?(ns)
    if instance_variable_get(history_name).include?(ns) && m.states[ns].unique?
      raise StateError, "#{ns} is a unique state and has already been taken"
    end
    instance_variable_get(history_name) << ns
    instance_variable_set(var_name, ns)
  end

  define_method("initialize_#{field}") do |initial|
    m.validate_state!(initial)
    raise StateError, "#{initial} is not possible initial state" unless m.states[initial].can_be_initial?
    instance_variable_set(history_name, Set.new)
    instance_variable_set(var_name, initial)
  end

  define_method("final_#{field}_state?") do
    m.states[instance_variable_get(var_name)].final?
  end
end