alamb commented on code in PR #7454: URL: https://github.com/apache/arrow-rs/pull/7454#discussion_r2083121878
########## parquet/src/arrow/arrow_reader/boolean_selector.rs: ########## @@ -0,0 +1,313 @@ +// 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::ops::Range; + +use arrow_array::{Array, BooleanArray}; +use arrow_buffer::{BooleanBuffer, BooleanBufferBuilder, MutableBuffer}; +use arrow_data::bit_iterator::BitIndexIterator; + +use super::{RowSelection, RowSelector}; + +/// A selection of rows, similar to [`RowSelection`], but based on a boolean array +#[derive(Debug, Clone, PartialEq)] +pub struct BooleanRowSelection { + selector: BooleanArray, +} + +impl BooleanRowSelection { + /// Create a new [`BooleanRowSelection] from a list of [`BooleanArray`]. + pub fn from_filters(filters: &[BooleanArray]) -> Self { + let arrays: Vec<&dyn Array> = filters.iter().map(|x| x as &dyn Array).collect(); + let result = arrow_select::concat::concat(&arrays).unwrap().into_data(); + let boolean_array = BooleanArray::from(result); + BooleanRowSelection { + selector: boolean_array, + } + } + + /// Create a new [`BooleanRowSelection`] with all rows unselected + pub fn new_unselected(row_count: usize) -> Self { + let buffer = BooleanBuffer::new_unset(row_count); + let boolean_array = BooleanArray::from(buffer); + BooleanRowSelection { selector: boolean_array } + } + + /// Create a new [`BooleanRowSelection`] with all rows selected + pub fn new_selected(row_count: usize) -> Self { + let buffer = BooleanBuffer::new_set(row_count); + let boolean_array = BooleanArray::from(buffer); + BooleanRowSelection { selector: boolean_array } + } + + /// Returns a new [`BooleanRowSelection`] that selects the inverse of this [`BooleanRowSelection`]. + pub fn as_inverted(&self) -> Self { + let buffer = !self.selector.values(); + BooleanRowSelection { selector: BooleanArray::from(buffer) } + } + + /// Returns the number of rows selected by this [`BooleanRowSelection`]. + pub fn row_count(&self) -> usize { + self.selector.true_count() + } + + /// Create a new [`BooleanRowSelection`] from a list of consecutive ranges. + pub fn from_consecutive_ranges( + ranges: impl Iterator<Item = Range<usize>>, + total_rows: usize, + ) -> Self { + let mut buffer = BooleanBufferBuilder::new(total_rows); + let mut last_end = 0; + + for range in ranges { + let len = range.end - range.start; + if len == 0 { + continue; + } + + if range.start > last_end { + buffer.append_n(range.start - last_end, false); + } + buffer.append_n(len, true); + last_end = range.end; + } + + if last_end != total_rows { + buffer.append_n(total_rows - last_end, false); + } + + BooleanRowSelection { + selector: BooleanArray::from(buffer.finish()), + } + } + + /// Compute the union of two [`BooleanRowSelection`] + /// For example: + /// self: NNYYYYNNYYNYN + /// other: NYNNNNNNN + /// + /// returned: NYYYYYNNYYNYN + #[must_use] + pub fn union(&self, other: &Self) -> Self { + // use arrow::compute::kernels::boolean::or; + + let union_selectors = self.selector.values() | other.selector.values(); + + BooleanRowSelection { + selector: BooleanArray::from(union_selectors), + } + } + + /// Compute the intersection of two [`BooleanRowSelection`] + /// For example: + /// self: NNYYYYNNYYNYN + /// other: NYNNNNNNY + /// + /// returned: NNNNNNNNYYNYN + #[must_use] + pub fn intersection(&self, other: &Self) -> Self { + let intersection_selectors = self.selector.values() & other.selector.values(); + + BooleanRowSelection { + selector: BooleanArray::from(intersection_selectors), + } + } + + /// Combines this [`BooleanRowSelection`] with another using logical AND on the selected bits. + /// + /// Unlike intersection, the `other` [`BooleanRowSelection`] must have exactly as many set bits as `self`. + /// This method will keep only the bits in `self` that are also set in `other` + /// at the positions corresponding to `self`'s set bits. + pub fn and_then(&self, other: &Self) -> Self { Review Comment: I think the other thing we can and should do here is change the signature to take an owned `self` -- also for `intersection` -- the API now forces a new memory allocation. -- This is an automated message from the Apache Git Service. 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