rdblue commented on a change in pull request #3399: URL: https://github.com/apache/iceberg/pull/3399#discussion_r744320061
########## File path: python/src/iceberg/expressions.py ########## @@ -0,0 +1,107 @@ +# Licensed to the Apache Software Foundation (ASF) under one +# or more contributor license agreements. See the NOTICE file +# distributed with this work for additional information +# regarding copyright ownership. The ASF licenses this file +# to you under the Apache License, Version 2.0 (the +# "License"); you may not use this file except in compliance +# with the License. You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, +# software distributed under the License is distributed on an +# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +# KIND, either express or implied. See the License for the +# specific language governing permissions and limitations +# under the License. + +from enum import Enum, auto + + +class Operation(Enum): + """Operations to be used as components in expressions + + Various operations can be negated or reversed. Negating an + operation is as simple as using the built-in subtraction operator: + + >>> print(-Operation.TRUE) + Operation.FALSE + >>> print(-Operation.IS_NULL) + Operation.NOT_NULL + + Reversing an operation can be done using the built-in reversed() method: + >>> print(reversed(Operation.LT)) + Operation.GT + >>> print(reversed(Operation.EQ)) + Operation.NOT_EQ + + The above examples use the OPERATION_NEGATIONS and OPERATION_REVERSALS maps + which map each enum to it's negated enum or reversed enum, respectively. + + Raises: + ValueError: This is raised when attempting to negate or reverse + an operation that cannot be negated or reversed. + """ + + TRUE = auto() + FALSE = auto() + IS_NULL = auto() + NOT_NULL = auto() + IS_NAN = auto() + NOT_NAN = auto() + LT = auto() + LT_EQ = auto() + GT = auto() + GT_EQ = auto() + EQ = auto() + NOT_EQ = auto() + IN = auto() + NOT_IN = auto() + NOT = auto() + AND = auto() + OR = auto() + + def __neg__(self): + """Returns the operation used when this is negated.""" + + try: + return OPERATION_NEGATIONS[self] + except KeyError: + raise ValueError(f"No negation defined for operation {self}") + + def __reversed__(self): + """Returns the equivalent operation when the left and right operands are exchanged.""" Review comment: I have a similar concern about `reversed(expr)` as above. But it turns out that we don't actually use `flipLR` anywhere in the Java codebase right now. I think we probably refactored out all of the uses, so we should just remove this for now. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
