def calc_eval(node):
"""
Actually do the calculation.
"""
if isinstance(node, ast.Expr): # Top level expression
return calc_eval(node.value)
elif isinstance(node, ast.Load): # ignore
return
elif isinstance(node, ast.Name): # <constant>
if node.id in constants:
return constants[node.id]
else:
raise NotImplementedError(node.id)
elif isinstance(node, ast.NameConstant):
return node.value
elif isinstance(node, ast.Num): # <number>
return node.n
elif (isinstance(node, ast.operator) or
isinstance(node, ast.unaryop) or
isinstance(node, ast.cmpop)): # <operator>
if type(node) in operators:
return operators[type(node)]
else:
raise KeyError(type(node).__name__)
elif isinstance(node, ast.UnaryOp): # <operator> <operand>
return calc_eval(node.op)(calc_eval(node.operand))
elif isinstance(node, ast.BinOp): # <left> <operator> <right>
return calc_eval(node.op)(calc_eval(node.left), calc_eval(node.right))
elif isinstance(node, ast.Compare): # boolean comparisons are more tricky
comparisons = zip(node.ops, pairwise([node.left] + node.comparators))
return all(calc_eval(op)(calc_eval(left), calc_eval(right)) for op, (left, right) in comparisons)
else:
raise TypeError(node)
def visit_Compare(self, node):
comparisons = zip(node.ops, pairwise([node.left] + node.comparators))
try:
return all(operators[op.__class__](self.visit(left), self.visit(right))
for op, (left, right) in comparisons)
except KeyError:
raise CalcError("invalid operator")
def calc_eval(node):
"""Actually do the calculation.
"""
# ast.Load is always preceded by something else
assert not isinstance(node, ast.Load)
if isinstance(node, ast.Expr): # Top level expression
return calc_eval(node.value)
elif isinstance(node, ast.Name): # <constant>
if node.id in identifiers:
return identifiers[node.id]
else:
raise NotImplementedError(node.id)
elif isinstance(node, ast.Call):
eval_args = [calc_eval(arg) for arg in node.args]
try:
return calc_eval(node.func)(*eval_args)
except TypeError as ex:
raise ValueError(str(ex))
elif isinstance(node, ast.NameConstant):
return node.value
elif isinstance(node, ast.Num): # <number>
return node.n
elif (isinstance(node, ast.operator) or
isinstance(node, ast.unaryop) or
isinstance(node, ast.cmpop)): # <operator>
if type(node) in operators:
return operators[type(node)]
else:
raise KeyError(type(node).__name__.lower())
elif isinstance(node, ast.UnaryOp): # <operator> <operand>
return calc_eval(node.op)(calc_eval(node.operand))
elif isinstance(node, ast.BinOp): # <left> <operator> <right>
return calc_eval(node.op)(calc_eval(node.left), calc_eval(node.right))
elif isinstance(node, ast.Compare): # boolean comparisons are more tricky
comparisons = zip(node.ops, pairwise([node.left] + node.comparators))
return all(calc_eval(op)(calc_eval(left), calc_eval(right)) for op, (left, right) in comparisons)
else:
raise TypeError(node)
