coderfender commented on code in PR #21030: URL: https://github.com/apache/datafusion/pull/21030#discussion_r2984939986
########## datafusion/ffi/src/ffi_option.rs: ########## @@ -0,0 +1,133 @@ +// 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. + +//! FFI-safe Option and Result types that do not require `IStable` bounds. +//! +//! stabby's `Option<T>` and `Result<T, E>` require `T: IStable` for niche +//! optimization. Many of our FFI structs contain self-referential function +//! pointers and cannot implement `IStable`. These simple `#[repr(C)]` types +//! provide the same FFI-safe semantics without that constraint. + +/// An FFI-safe option type. +#[repr(C, u8)] +#[derive(Debug, Clone)] +pub enum FfiOption<T> { + Some(T), + None, +} + +impl<T> From<Option<T>> for FfiOption<T> { + fn from(opt: Option<T>) -> Self { + match opt { + Some(v) => FfiOption::Some(v), + None => FfiOption::None, + } + } +} + +impl<T> From<FfiOption<T>> for Option<T> { + fn from(opt: FfiOption<T>) -> Self { + match opt { + FfiOption::Some(v) => Some(v), + FfiOption::None => None, + } + } +} + +impl<T> FfiOption<T> { + pub fn as_ref(&self) -> Option<&T> { + match self { + FfiOption::Some(v) => Some(v), + FfiOption::None => None, + } + } + + pub fn map<U, F: FnOnce(T) -> U>(self, f: F) -> FfiOption<U> { + match self { + FfiOption::Some(v) => FfiOption::Some(f(v)), + FfiOption::None => FfiOption::None, + } + } + + pub fn into_option(self) -> Option<T> { + self.into() + } +} + +/// An FFI-safe result type. +#[repr(C, u8)] +#[derive(Debug, Clone)] +pub enum FfiResult<T, E> { Review Comment: Sure . let me make an update to the case here -- 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]
