def eval_expr(context, expr, expected_type):
"""
Eval the provided expression
:type context: ctx.EvaluationContext
:param context: Evaluation context.
:type expr: ast.Expr
:param expr: The expression to evaluate
:type expected_type: type_util.IsType
:param expected_type: The expected type of this computation.
:rtype: str | float
:return: Returns the computed value
"""
if len(expr.expr_tree) == 1:
return eval_rhs(context, expr.expr_tree[0], expected_type)
if isinstance(expected_type, type_util.Number):
result = 0
cast_func = float
elif isinstance(expected_type, type_util.String):
result = ""
cast_func = str
else:
raise exception.BananaEvalBug(
"Expected type for an expression can only be "
"'TypeNumber' or 'TypeString', got '{}'".format(
str(expected_type)))
current_operator = operator.add
for el in expr.expr_tree:
if isinstance(el, basestring) and el in ['+', '-', '*', '/']:
current_operator = get_op_func(el)
else:
value = eval_rhs(context, el, expected_type)
value = cast_func(value)
result = current_operator(result, value)
return result
def get_op_func(op_str):
if op_str == '+':
return operator.add
if op_str == '-':
return operator.sub
if op_str == '*':
return operator.mul
if op_str == '/':
return operator.div
raise exception.BananaEvalBug("Unknown operator '{}'".format(op_str))
def set_variable(self, name, value):
"""Set the variable value."""
if isinstance(value, tuple) and len(value) == 2:
comp_type, config = value
comp_name = name.varname.inner_val()
self._components[comp_name] = comp_type(comp_name, config)
self._variables[comp_name] = config
elif not set_property(self._variables, name, value):
raise exception.BananaEvalBug(
"set_variable can only be used with DotPath or Ident.")