scovich commented on code in PR #7919: URL: https://github.com/apache/arrow-rs/pull/7919#discussion_r2205857946
########## parquet-variant/src/path.rs: ########## @@ -0,0 +1,64 @@ +// 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. +use std::{borrow::Cow, ops::Deref}; + +/// Represents a qualified path to a potential subfield or index of a variant value. +#[derive(Debug, Clone)] +pub struct VariantPath<'a>(Vec<VariantPathElement<'a>>); + +impl<'a> VariantPath<'a> { + pub fn new(path: Vec<VariantPathElement<'a>>) -> Self { + Self(path) + } + + pub fn path(&self) -> &Vec<VariantPathElement> { + &self.0 + } +} + +impl<'a> From<Vec<VariantPathElement<'a>>> for VariantPath<'a> { + fn from(value: Vec<VariantPathElement<'a>>) -> Self { + Self::new(value) + } +} + +impl<'a> Deref for VariantPath<'a> { + type Target = Vec<VariantPathElement<'a>>; Review Comment: Normally `Deref` should go "all the way" and invoke Deref for the target type as well? Which in this case would mean `Target = [VariantPathElement<'a>]`? ########## parquet-variant/src/variant.rs: ########## @@ -1063,6 +1064,34 @@ impl<'m, 'v> Variant<'m, 'v> { _ => None, } } + + /// Return a new Variant with the path followed. + /// + /// If the path is not found, `None` is returned. + pub fn get_path(&self, path: &VariantPath) -> Option<Variant> { + let mut output = self.clone(); + for element in path.deref() { Review Comment: It's not usually necessary to invoke `deref` directly? ########## parquet-variant/src/variant.rs: ########## @@ -1063,6 +1064,34 @@ impl<'m, 'v> Variant<'m, 'v> { _ => None, } } + + /// Return a new Variant with the path followed. + /// + /// If the path is not found, `None` is returned. + pub fn get_path(&self, path: &VariantPath) -> Option<Variant> { + let mut output = self.clone(); + for element in path.deref() { + match element { + VariantPathElement::Field { name } => { + let Variant::Object(variant_object) = output else { + return None; + }; + let field = variant_object.get(name); + let field = field?; + output = field; + } + VariantPathElement::Index { index } => { + let Variant::List(variant_list) = output else { + return None; + }; + let index = variant_list.get(*index); + let index = index?; + output = index; + } + } Review Comment: ```suggestion output = match element { VariantPathElement::Field { name } => output.get_object_field(name)?, VariantPathElement::Index { index } => output.get_array_element(*index)?, }; ``` ########## parquet-variant/src/variant.rs: ########## @@ -1063,6 +1064,34 @@ impl<'m, 'v> Variant<'m, 'v> { _ => None, } } + + /// Return a new Variant with the path followed. + /// + /// If the path is not found, `None` is returned. + pub fn get_path(&self, path: &VariantPath) -> Option<Variant> { + let mut output = self.clone(); + for element in path.deref() { Review Comment: ... but apparently this is a context where deref isn't automatic (tried it in playground). Tho we could perhaps be more clear by ```suggestion for element in path.iter() { ``` ... which _does_ deref automatically? ########## parquet-variant-compute/src/variant_get.rs: ########## @@ -0,0 +1,202 @@ +// 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. +use std::sync::Arc; + +use arrow::{ + array::{Array, ArrayRef}, + compute::CastOptions, + error::Result, +}; +use arrow_schema::{ArrowError, Field}; +use parquet_variant::path::VariantPath; + +use crate::{VariantArray, VariantArrayBuilder}; + +/// Returns an array with the specified path extracted from the variant values. +/// +/// The return array type depends on the `as_type` field of the options parameter +/// 1. `as_type: None`: a VariantArray is returned. The values in this new VariantArray will point +/// to the specified path. +/// 2. `as_type: Some(<specific field>)`: an array of the specified type is returned. +pub fn variant_get(input: &ArrayRef, options: GetOptions) -> Result<ArrayRef> { + let variant_array: &VariantArray = input.as_any().downcast_ref().ok_or_else(|| { + ArrowError::InvalidArgumentError( + "expected a VariantArray as the input for variant_get".to_owned(), + ) + })?; + + if let Some(as_type) = options.as_type { + return Err(ArrowError::NotYetImplemented(format!( + "getting a {} from a VariantArray is not implemented yet", + as_type + ))); + } + + let mut builder = VariantArrayBuilder::new(variant_array.len()); + for i in 0..variant_array.len() { + let new_variant = variant_array.value(i); + // TODO: perf? + let new_variant = new_variant.get_path(&options.path); + if let Some(new_variant) = new_variant { + // TODO: we're decoding the value and doing a copy into a variant value again. This + // copy can be much smarter. + builder.append_variant(new_variant); Review Comment: Can't we just do a directly byte-slice copy? The input is either fully validated or the caller has asserted that the bytes are correct. Maybe a `VariantArray::value_bytes` method and then `VariantArrayBuilder::append_variant_bytes`? Hopefully, that would also (eventually) map more nicely to a view-based approach. -- 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: github-unsubscr...@arrow.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
