def eval(self):
prod = self.value[0].eval()
for op, val in _operatorOperands(self.value[1:]):
try:
if op == '*':
prod *= val.eval()
elif op == '/':
prod /= float(val.eval())
except ZeroDivisionError as e:
msg = _("ZeroDivisionError: %s") % e
raise exception.EvaluatorParseException(reason=msg)
return prod
def eval(self):
result = self.value
if (isinstance(result, str)
and re.match(r"^[a-zA-Z_]+\.[a-zA-Z_]+$", result)):
(which_dict, entry) = result.split('.')
try:
result = _vars[which_dict][entry]
except KeyError as e:
msg = _("KeyError: %s") % e
raise exception.EvaluatorParseException(reason=msg)
except TypeError as e:
msg = _("TypeError: %s") % e
raise exception.EvaluatorParseException(reason=msg)
try:
result = int(result)
except ValueError:
try:
result = float(result)
except ValueError as e:
msg = _("ValueError: %s") % e
raise exception.EvaluatorParseException(reason=msg)
return result
def evaluate(expression, **kwargs):
"""Evaluates an expression.
Provides the facility to evaluate mathematical expressions, and to
substitute variables from dictionaries into those expressions.
Supports both integer and floating point values, and automatic
promotion where necessary.
"""
global _parser
if _parser is None:
_parser = _def_parser()
global _vars
_vars = kwargs
try:
result = _parser.parseString(expression, parseAll=True)[0]
except pyparsing.ParseException as e:
msg = _("ParseException: %s") % e
raise exception.EvaluatorParseException(reason=msg)
return result.eval()