viirya commented on code in PR #3553: URL: https://github.com/apache/arrow-rs/pull/3553#discussion_r1084401459
########## arrow-array/src/builder/primitive_run_builder.rs: ########## @@ -0,0 +1,297 @@ +// 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::{any::Any, sync::Arc}; + +use crate::{types::RunEndIndexType, ArrayRef, ArrowPrimitiveType, RunArray}; + +use super::{ArrayBuilder, PrimitiveBuilder}; + +use arrow_buffer::ArrowNativeType; + +/// Array builder for [`RunArray`] that encodes primitive values. +/// +/// # Example: +/// +/// ``` +/// +/// # use arrow_array::builder::PrimitiveRunBuilder; +/// # use arrow_array::cast::as_primitive_array; +/// # use arrow_array::types::{UInt32Type, Int16Type}; +/// # use arrow_array::{Array, UInt32Array, Int16Array}; +/// +/// let mut builder = +/// PrimitiveRunBuilder::<Int16Type, UInt32Type>::new(); +/// builder.append_value(1234); +/// builder.append_value(1234); +/// builder.append_value(1234); +/// builder.append_null(); +/// builder.append_value(5678); +/// builder.append_value(5678); +/// let array = builder.finish(); +/// +/// assert_eq!( +/// array.run_ends(), +/// &Int16Array::from(vec![Some(3), Some(4), Some(6)]) +/// ); +/// +/// let av = array.values(); +/// +/// assert!(!av.is_null(0)); +/// assert!(av.is_null(1)); +/// assert!(!av.is_null(2)); +/// +/// // Values are polymorphic and so require a downcast. +/// let ava: &UInt32Array = as_primitive_array::<UInt32Type>(av.as_ref()); +/// +/// assert_eq!(ava, &UInt32Array::from(vec![Some(1234), None, Some(5678)])); +/// ``` +#[derive(Debug)] +pub struct PrimitiveRunBuilder<R, V> +where + R: RunEndIndexType, + V: ArrowPrimitiveType, +{ + run_ends_builder: PrimitiveBuilder<R>, + values_builder: PrimitiveBuilder<V>, + current_value: Option<V::Native>, + current_run_end_index: usize, + prev_run_end_index: usize, +} + +impl<R, V> Default for PrimitiveRunBuilder<R, V> +where + R: RunEndIndexType, + V: ArrowPrimitiveType, +{ + fn default() -> Self { + Self::new() + } +} + +impl<R, V> PrimitiveRunBuilder<R, V> +where + R: RunEndIndexType, + V: ArrowPrimitiveType, +{ + /// Creates a new `PrimitiveRunBuilder` + pub fn new() -> Self { + Self { + run_ends_builder: PrimitiveBuilder::new(), + values_builder: PrimitiveBuilder::new(), + current_value: None, + current_run_end_index: 0, + prev_run_end_index: 0, + } + } + + /// Creates a new `PrimitiveRunBuilder` with the provided capacity + /// + /// `capacity`: the expected number of run-end encoded values. + pub fn with_capacity(capacity: usize) -> Self { + Self { + run_ends_builder: PrimitiveBuilder::with_capacity(capacity), + values_builder: PrimitiveBuilder::with_capacity(capacity), + current_value: None, + current_run_end_index: 0, + prev_run_end_index: 0, + } + } +} + +impl<R, V> ArrayBuilder for PrimitiveRunBuilder<R, V> +where + R: RunEndIndexType, + V: ArrowPrimitiveType, +{ + /// Returns the builder as a non-mutable `Any` reference. + fn as_any(&self) -> &dyn Any { + self + } + + /// Returns the builder as a mutable `Any` reference. + fn as_any_mut(&mut self) -> &mut dyn Any { + self + } + + /// Returns the boxed builder as a box of `Any`. + fn into_box_any(self: Box<Self>) -> Box<dyn Any> { + self + } + + /// Returns the number of array slots in the builder + fn len(&self) -> usize { + let mut len = self.run_ends_builder.len(); + // If there is an ongoing run yet to be added, include it in the len + if self.prev_run_end_index != self.current_run_end_index { + len += 1; + } + len + } + + /// Returns whether the number of array slots is zero + fn is_empty(&self) -> bool { + self.current_run_end_index == 0 + } + + /// Builds the array and reset this builder. + fn finish(&mut self) -> ArrayRef { + Arc::new(self.finish()) + } + + /// Builds the array without resetting the builder. + fn finish_cloned(&self) -> ArrayRef { + Arc::new(self.finish_cloned()) + } +} + +impl<R, V> PrimitiveRunBuilder<R, V> +where + R: RunEndIndexType, + V: ArrowPrimitiveType, +{ + /// Appends optional value to the logical array encoded by the RunArray. + pub fn append_option(&mut self, value: Option<V::Native>) { + if self.current_run_end_index == 0 { + self.current_run_end_index = 1; + self.current_value = value; + return; + } + if self.current_value != value { + self.append_run_end(); + self.current_value = value; + } + + self.current_run_end_index += 1; + } + + /// Appends value to the logical array encoded by the run-ends array. + pub fn append_value(&mut self, value: V::Native) { + self.append_option(Some(value)) + } + + /// Appends null to the logical array encoded by the run-ends array. + pub fn append_null(&mut self) { + self.append_option(None) + } + + /// Creates the RunArray and resets the builder. + /// Panics if RunArray cannot be built. + pub fn finish(&mut self) -> RunArray<R> { + // write the last run end to the array. + self.append_run_end(); + + // reset the run index to zero. + self.current_value = None; + self.current_run_end_index = 0; + + // build the run encoded array by adding run_ends and values array as its children. + let run_ends_array = self.run_ends_builder.finish(); + let values_array = self.values_builder.finish(); + RunArray::<R>::try_new(&run_ends_array, &values_array).unwrap() + } + + /// Creates the RunArray and without resetting the builder. + /// Panics if RunArray cannot be built. + pub fn finish_cloned(&self) -> RunArray<R> { + let mut run_ends_array = self.run_ends_builder.finish_cloned(); + let mut values_array = self.values_builder.finish_cloned(); + + // Add current run if one exists + if self.prev_run_end_index != self.current_run_end_index { + let mut run_end_builder = run_ends_array.into_builder().unwrap(); + let mut values_builder = values_array.into_builder().unwrap(); + self.append_run_end_with_builders(&mut run_end_builder, &mut values_builder); + run_ends_array = run_end_builder.finish(); + values_array = values_builder.finish(); + } + + RunArray::try_new(&run_ends_array, &values_array).unwrap() + } + + // Appends the current run to the array. There are scenarios where this function can be called + // multiple times before getting a new value. e.g. appending different value immediately following + // finish_cloned. + fn append_run_end(&mut self) { + // empty array or the function called without appending any value. + if self.current_run_end_index == 0 + || self.prev_run_end_index == self.current_run_end_index + { + return; + } + let run_end_index = R::Native::from_usize(self.current_run_end_index) + .unwrap_or_else(|| panic!( + "Cannot convert the value {} from `usize` to native form of arrow datatype {}", + self.current_run_end_index, + R::DATA_TYPE + )); + self.run_ends_builder.append_value(run_end_index); + self.values_builder.append_option(self.current_value); + self.prev_run_end_index = self.current_run_end_index; + } + + // Similar to `append_run_end` but on custom builders. + fn append_run_end_with_builders( + &self, + run_ends_builder: &mut PrimitiveBuilder<R>, + values_builder: &mut PrimitiveBuilder<V>, + ) { + let run_end_index = R::Native::from_usize(self.current_run_end_index) + .unwrap_or_else(|| panic!( + "Cannot convert the value {} from `usize` to native form of arrow datatype {}", + self.current_run_end_index, + R::DATA_TYPE + )); + run_ends_builder.append_value(run_end_index); + values_builder.append_option(self.current_value); + } +} + +#[cfg(test)] +mod tests { + use crate::builder::PrimitiveRunBuilder; + use crate::cast::as_primitive_array; + use crate::types::{Int16Type, UInt32Type}; + use crate::{Int16Array, UInt32Array}; + #[test] + fn test_primitive_ree_array_builder() { + let mut builder = PrimitiveRunBuilder::<Int16Type, UInt32Type>::new(); + builder.append_value(1234); + builder.append_value(1234); + builder.append_value(1234); + builder.append_null(); + builder.append_value(5678); + builder.append_value(5678); + let array = builder.finish(); + + assert_eq!( + array.run_ends(), + &Int16Array::from(vec![Some(3), Some(4), Some(6)]) + ); + Review Comment: It should be 6, I think. -- This is an automated message from the Apache Git Service. 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