text: from .utils import Serialize
  
  ###{standalone
  
  class Symbol(Serialize):
      __slots__ = ('name',)
  
      is_term = NotImplemented
  
      def __init__(self, name):
          self.name = name
  
      def __eq__(self, other):
          assert isinstance(other, Symbol), other
          return self.is_term == other.is_term and self.name == other.name
  
      def __ne__(self, other):
          return not (self == other)
  
      def __hash__(self):
          return hash(self.name)
  
      def __repr__(self):
          return '%s(%r)' % (type(self).__name__, self.name)
  
      fullrepr = property(__repr__)
  
  
  class Terminal(Symbol):
      __serialize_fields__ = 'name', 'filter_out'
  
      is_term = True
  
      def __init__(self, name, filter_out=False):
          self.name = name
          self.filter_out = filter_out
  
      @property
      def fullrepr(self):
          return '%s(%r, %r)' % (type(self).__name__, self.name, self.filter_out)
  
  
  class NonTerminal(Symbol):
      __serialize_fields__ = 'name',
  
      is_term = False
  
  
  class RuleOptions(Serialize):
      __serialize_fields__ = 'keep_all_tokens', 'expand1', 'priority', 'template_source', 'empty_indices'
  
      def __init__(self, keep_all_tokens=False, expand1=False, priority=None, template_source=None, empty_indices=()):
          self.keep_all_tokens = keep_all_tokens
          self.expand1 = expand1
          self.priority = priority
          self.template_source = template_source
          self.empty_indices = empty_indices
  
      def __repr__(self):
          return 'RuleOptions(%r, %r, %r, %r)' % (
              self.keep_all_tokens,
              self.expand1,
              self.priority,
              self.template_source
          )
  
  
  class Rule(Serialize):
      """
          origin : a symbol
          expansion : a list of symbols
          order : index of this expansion amongst all rules of the same name
      """
      __slots__ = ('origin', 'expansion', 'alias', 'options', 'order', '_hash')
  
      __serialize_fields__ = 'origin', 'expansion', 'order', 'alias', 'options'
      __serialize_namespace__ = Terminal, NonTerminal, RuleOptions
  
      def __init__(self, origin, expansion, order=0, alias=None, options=None):
          self.origin = origin
          self.expansion = expansion
          self.alias = alias
          self.order = order
          self.options = options or RuleOptions()
          self._hash = hash((self.origin, tuple(self.expansion)))
  
      def _deserialize(self):
          self._hash = hash((self.origin, tuple(self.expansion)))
  
      def __str__(self):
          return '<%s : %s>' % (self.origin.name, ' '.join(x.name for x in self.expansion))
  
      def __repr__(self):
          return 'Rule(%r, %r, %r, %r)' % (self.origin, self.expansion, self.alias, self.options)
  
      def __hash__(self):
          return self._hash
  
      def __eq__(self, other):
          if not isinstance(other, Rule):
              return False
          return self.origin == other.origin and self.expansion == other.expansion
  
  
  ###}
  