Kontinuation commented on code in PR #699: URL: https://github.com/apache/sedona-db/pull/699#discussion_r2960184166
########## c/sedona-gdal/src/vector/layer.rs: ########## @@ -0,0 +1,118 @@ +// 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. + +//! Ported (and contains copied code) from georust/gdal: +//! <https://github.com/georust/gdal/blob/v0.19.0/src/vector/layer.rs>. +//! Original code is licensed under MIT. + +use std::marker::PhantomData; + +use crate::dataset::Dataset; +use crate::errors::{GdalError, Result}; +use crate::gdal_api::{call_gdal_api, GdalApi}; +use crate::gdal_dyn_bindgen::*; +use crate::vector::feature::{Feature, FieldDefn}; + +/// An OGR layer (borrowed from a Dataset). +pub struct Layer<'a> { + api: &'static GdalApi, + c_layer: OGRLayerH, + _dataset: PhantomData<&'a Dataset>, +} + +impl<'a> Layer<'a> { + pub(crate) fn new(api: &'static GdalApi, c_layer: OGRLayerH, _dataset: &'a Dataset) -> Self { + Self { + api, + c_layer, + _dataset: PhantomData, + } + } + + /// Return the raw C layer handle. + pub fn c_layer(&self) -> OGRLayerH { + self.c_layer + } + + /// Reset reading to the first feature. + pub fn reset_reading(&self) { + unsafe { call_gdal_api!(self.api, OGR_L_ResetReading, self.c_layer) }; + } + + /// Get the next feature (returns None when exhausted). + pub fn next_feature(&self) -> Option<Feature<'_>> { + let c_feature = unsafe { call_gdal_api!(self.api, OGR_L_GetNextFeature, self.c_layer) }; + if c_feature.is_null() { + None + } else { + Some(Feature::new(self.api, c_feature)) + } + } + + /// Create a field on this layer. + pub fn create_field(&self, field_defn: &FieldDefn) -> Result<()> { + let rv = unsafe { + call_gdal_api!( + self.api, + OGR_L_CreateField, + self.c_layer, + field_defn.c_field_defn(), + 1 // bApproxOK + ) + }; + if rv != OGRERR_NONE { + return Err(GdalError::OgrError { + err: rv, + method_name: "OGR_L_CreateField", + }); + } + Ok(()) + } + + /// Get the number of features in this layer. + /// + /// If `force` is true, the count will be computed even if it is expensive. + pub fn feature_count(&self, force: bool) -> i64 { + unsafe { + call_gdal_api!( + self.api, + OGR_L_GetFeatureCount, + self.c_layer, + if force { 1 } else { 0 } + ) + } + } + + /// Iterate over all features. + pub fn features(&self) -> FeatureIterator<'_> { + self.reset_reading(); + FeatureIterator { layer: self } + } +} + +/// Iterator over features in a layer. +pub struct FeatureIterator<'a> { + layer: &'a Layer<'a>, +} + +impl<'a> Iterator for FeatureIterator<'a> { + type Item = Feature<'a>; Review Comment: Thanks. I adjusted `Layer::features` to take `&mut self` so callers cannot create multiple iterators from the same layer borrow at once, which avoids the interference concern for this API shape. I am leaving the lifetime structure as-is for now and will revisit it only if we run into a concrete borrow ergonomics issue later. -- 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]
