def _compile_impossible(self, element, *args, **kwargs):
# Override this to avoid VoidRefs disabling entire rules/grammars.
# Use a special <_impossible> private rule instead. Only add the
# special rule if it isn't in the result grammar.
grammar = args[0]
if "_impossible" not in grammar.rule_names:
# Check that the impossible literal contains only valid words.
words = set(self.impossible_literal.split())
valid_literal = bool(words)
for word in words:
if not valid_literal:
break
if not self.engine.check_valid_word(word):
valid_literal = False
if valid_literal:
expansion = jsgf.Literal(self.impossible_literal)
else:
# Fallback on a NullRef. There are some problems with using
# these, but they get the job done for simple rules.
expansion = jsgf.NullRef()
grammar.add_rule(
jsgf.Rule(name="_impossible",
visible=False,
expansion=expansion))
return jsgf.NamedRuleRef("_impossible")
def _compile_list_ref(self, element, *args, **kwargs):
name = element.list.name.replace(" ", "_")
return jsgf.NamedRuleRef(name)