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use std::collections::VecDeque;
use crate::{
encoding::hybrid_rle::{self, HybridRleDecoder},
indexes::Interval,
page::{split_buffer, DataPage},
read::levels::get_bit_width,
};
use super::hybrid_rle::{HybridDecoderBitmapIter, HybridRleIter};
pub(super) fn dict_indices_decoder(page: &DataPage) -> hybrid_rle::HybridRleDecoder {
let (_, _, indices_buffer) = split_buffer(page);
let bit_width = indices_buffer[0];
let indices_buffer = &indices_buffer[1..];
hybrid_rle::HybridRleDecoder::new(indices_buffer, bit_width as u32, page.num_values())
}
#[derive(Debug)]
pub enum DefLevelsDecoder<'a> {
Bitmap(HybridDecoderBitmapIter<'a>),
Levels(HybridRleDecoder<'a>, u32),
}
impl<'a> DefLevelsDecoder<'a> {
pub fn new(page: &'a DataPage) -> Self {
let (_, def_levels, _) = split_buffer(page);
let max_def_level = page.descriptor.max_def_level;
if max_def_level == 1 {
let iter = hybrid_rle::Decoder::new(def_levels, 1);
let iter = HybridRleIter::new(iter, page.num_values());
Self::Bitmap(iter)
} else {
let iter =
HybridRleDecoder::new(def_levels, get_bit_width(max_def_level), page.num_values());
Self::Levels(iter, max_def_level as u32)
}
}
}
#[derive(Debug, Clone)]
pub struct OptionalValues<T, V: Iterator<Item = bool>, I: Iterator<Item = T>> {
validity: V,
values: I,
}
impl<T, V: Iterator<Item = bool>, I: Iterator<Item = T>> OptionalValues<T, V, I> {
pub fn new(validity: V, values: I) -> Self {
Self { validity, values }
}
}
impl<T, V: Iterator<Item = bool>, I: Iterator<Item = T>> Iterator for OptionalValues<T, V, I> {
type Item = Option<T>;
#[inline]
fn next(&mut self) -> Option<Self::Item> {
self.validity
.next()
.map(|x| if x { self.values.next() } else { None })
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.validity.size_hint()
}
}
#[derive(Debug, Clone)]
pub struct SliceFilteredIter<I> {
iter: I,
selected_rows: VecDeque<Interval>,
current_remaining: usize,
current: usize,
total_length: usize,
}
impl<I> SliceFilteredIter<I> {
pub fn new(iter: I, selected_rows: VecDeque<Interval>) -> Self {
let total_length = selected_rows.iter().map(|i| i.length).sum();
Self {
iter,
selected_rows,
current_remaining: 0,
current: 0,
total_length,
}
}
}
impl<T, I: Iterator<Item = T>> Iterator for SliceFilteredIter<I> {
type Item = T;
#[inline]
fn next(&mut self) -> Option<Self::Item> {
if self.current_remaining == 0 {
if let Some(interval) = self.selected_rows.pop_front() {
let item = self.iter.nth(interval.start - self.current);
self.current = interval.start + interval.length;
self.current_remaining = interval.length - 1;
self.total_length -= 1;
item
} else {
None
}
} else {
self.current_remaining -= 1;
self.total_length -= 1;
self.iter.next()
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
(self.total_length, Some(self.total_length))
}
}
#[cfg(test)]
mod test {
use std::collections::VecDeque;
use super::*;
#[test]
fn basic() {
let iter = 0..=100;
let intervals = vec![
Interval::new(0, 2),
Interval::new(20, 11),
Interval::new(31, 1),
];
let a: VecDeque<Interval> = intervals.clone().into_iter().collect();
let mut a = SliceFilteredIter::new(iter, a);
let expected: Vec<usize> = intervals
.into_iter()
.flat_map(|interval| interval.start..(interval.start + interval.length))
.collect();
assert_eq!(expected, a.by_ref().collect::<Vec<_>>());
assert_eq!((0, Some(0)), a.size_hint());
}
}