declare.py 文件源码

def _aslimit(value, lc):
        if isinstance(value, string_types):
            module = ast.parse(value)
            if isinstance(module, ast.Module) and len(module.body) == 1 and isinstance(module.body[0], ast.Expr):
                def restrictedeval(expr):
                    if isinstance(expr, ast.Num):
                        return expr.n

                    elif isinstance(expr, ast.Name) and expr.id == "inf":
                        return femtocode.typesystem.inf

                    elif isinstance(expr, ast.Name) and expr.id == "pi":
                        return math.pi

                    elif isinstance(expr, ast.UnaryOp) and isinstance(expr.op, ast.USub):
                        return -restrictedeval(expr.operand)

                    elif isinstance(expr, ast.BinOp) and isinstance(expr.op, ast.Add):
                        return restrictedeval(expr.left) + restrictedeval(expr.right)

                    elif isinstance(expr, ast.BinOp) and isinstance(expr.op, ast.Sub):
                        return restrictedeval(expr.left) - restrictedeval(expr.right)

                    elif isinstance(expr, ast.BinOp) and isinstance(expr.op, ast.Mult):
                        return restrictedeval(expr.left) * restrictedeval(expr.right)

                    elif isinstance(expr, ast.BinOp) and isinstance(expr.op, ast.Div):
                        return restrictedeval(expr.left) / restrictedeval(expr.right)

                    elif isinstance(expr, ast.BinOp) and isinstance(expr.op, ast.Pow):
                        return restrictedeval(expr.left) ** restrictedeval(expr.right)

                    elif isinstance(expr, ast.Call) and isinstance(expr.func, ast.Name) and expr.func.id == "almost" and len(expr.args) == 1 and len(expr.keywords) == 0 and expr.kwargs is None and expr.starargs is None:
                        return femtocode.typesystem.almost(restrictedeval(expr.args[0]))

                    else:
                        raise DatasetDeclaration.Error(lc, "couldn't parse as a min/max/least/most limit: {0}".format(value))

                return restrictedeval(module.body[0].value)

        elif isinstance(value, (int, long, float)):
            return value

        elif isinstance(value, femtocode.typesystem.almost) and isinstance(value.real, (int, long, float)):
            return value

        else:
            raise DatasetDeclaration.Error(lc, "unrecognized type for min/max/least/most limit: {0}".format(value))