def _id(self, symbol):
if not isinstance(symbol, Identifier):
raise FolSemanticError(symbol)
try:
return self.ids[symbol], True
except KeyError:
i = "%s%d" % ("".join(
c for c in str(symbol) if c in string.letters + "_")
or "i", len(self.ids))
self.ids[symbol] = i = FolFormula.Identifier(i, symbol.kind)
return i, True
class Signature:
a = FolFormula.Identifier(u'α', 'predicate')
v = FolFormula.Identifier('v', 'variable')
u = FolFormula.Identifier('u', 'variable')