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//! This module implements a Quad Wavelet Tree to support access, rank, and select
//! queries on a vector of unsigned integers.
//!
//! This data structure supports three operations:
//! - `get(i)` accesses the `i`-th symbols of the indexed sequence;
//! - `rank(s, i)` counts the number of occurrences of symbol `s` up to position `i` excluded;
//! - `select(s, i)` returns the position of the `i`-th occurrence of symbol `s`.
//!
//! We can index vectors of length up to 2^{43} symbols.
use crate::utils::{msb, stable_partition_of_4};
use crate::{AccessUnsigned, RankUnsigned, SelectUnsigned, SpaceUsage, WTSupport};
use crate::{QVector, QVectorBuilder}; // Traits
use serde::{Deserialize, Serialize};
use std::marker::PhantomData;
// Traits bound
use num_traits::{AsPrimitive, PrimInt, Unsigned};
use std::ops::{Shl, Shr};
mod prefetch_support;
use crate::quadwt::prefetch_support::PrefetchSupport;
/// Alias for the trait bounds to be satisfied by a data structure
/// to support `rank` and `select` queries at each level of the wavelet tree.
/// We need an alias to avoid repeating a lot of bounds here and there.
pub trait RSforWT: From<QVector> + WTSupport + SpaceUsage + Default {}
// Generic implementation for any T
impl<T> RSforWT for T where T: From<QVector> + WTSupport + SpaceUsage + Default {}
/// Alias for the trait bounds of the type T to be indexable in the
/// wavelet tree.
pub trait WTIndexable:
Unsigned + PrimInt + Ord + Shr<usize> + Shl<usize> + AsPrimitive<u8>
{
}
impl<T> WTIndexable for T
where
T: Unsigned + PrimInt + Ord + Shr<usize> + Shl<usize> + AsPrimitive<u8>,
u8: AsPrimitive<T>,
{
}
/// The generic RS is the data structure we use to index a quaternary
/// sequence to support `access, `rank`, and `select` queries.
///
/// The const generic `PREFETCH_DATA` specifies if the wavelet tree
/// is augmented with extra data to support a deeper level of prefetching.
/// This is needed only for sequences such that data about superblocks and
/// blocks do not fit in L3 cache.
#[derive(Default, Clone, PartialEq, Debug, Serialize, Deserialize)]
pub struct QWaveletTree<T, RS, const WITH_PREFETCH_SUPPORT: bool = false> {
n: usize, // The length of the represented sequence
n_levels: usize, // The number of levels of the wavelet matrix
sigma: T, // The largest symbol in the sequence. *NOTE*: It's not +1 because it may overflow
qvs: Vec<RS>, // A quad vector for each level
prefetch_support: Option<Vec<PrefetchSupport>>,
}
impl<T, RS, const WITH_PREFETCH_SUPPORT: bool> QWaveletTree<T, RS, WITH_PREFETCH_SUPPORT>
where
T: WTIndexable,
u8: AsPrimitive<T>,
RS: RSforWT,
{
/// Builds the wavelet tree of the `sequence` of unsigned integers.
/// The input sequence is **destroyed**.
///
/// The alphabet size `sigma` is the largest value in the `sequence`.
/// Both space usage and query time of a QWaveletTree depend on
/// $$\lfloor\log_2 (\sigma-1)\rfloor + 1$$ (i.e., the length of the
/// binary representation of values in the sequence).
/// For this reason, it may be convenient for both space usage and query time to
/// remap the alphabet to form a consecutive range [0, d], where d is
/// the number of distinct values in `sequence`.
///
/// ## Panics
/// Panics if the sequence is longer than the largest possible length.
/// The largest possible length is 2^{43} symbols.
///
/// # Examples
/// ```
/// use qwt::QWT256;
///
/// let data = vec![1u8, 0, 1, 0, 2, 4, 5, 3];
///
/// let qwt = QWT256::from(data);
///
/// assert_eq!(qwt.len(), 8);
/// ```
pub fn new(sequence: &mut [T]) -> Self {
if sequence.is_empty() {
return Self {
n: 0,
n_levels: 0,
sigma: T::zero(),
qvs: vec![RS::default()],
prefetch_support: None,
};
}
let sigma = *sequence.iter().max().unwrap();
let log_sigma = msb(sigma) + 1; // Note that sigma equals the largest symbol, so it's already "alphabet_size - 1"
let n_levels = ((log_sigma + 1) / 2) as usize; // TODO: if log_sigma is odd, the FIRST level should be a binary vector!
let mut prefetch_support = Vec::with_capacity(n_levels); // used only if WITH_PREFETCH_SUPPORT
let mut qvs = Vec::<RS>::with_capacity(n_levels);
let mut shift = 2 * (n_levels - 1);
for _level in 0..n_levels {
let mut cur_qv = QVectorBuilder::with_capacity(sequence.len());
for &symbol in sequence.iter() {
let two_bits: u8 = (symbol >> shift).as_() & 3; // take the last 2 bits
cur_qv.push(two_bits);
}
let qv = cur_qv.build();
if WITH_PREFETCH_SUPPORT {
let pfs = PrefetchSupport::new(&qv, 11); // 11 -> sample_rate = 2048
prefetch_support.push(pfs);
}
qvs.push(RS::from(qv));
stable_partition_of_4(sequence, shift);
if shift >= 2 {
shift -= 2;
}
}
qvs.shrink_to_fit();
Self {
n: sequence.len(),
n_levels,
sigma,
qvs,
prefetch_support: if WITH_PREFETCH_SUPPORT {
Some(prefetch_support)
} else {
None
},
}
}
/// Returns the length of the indexed sequence.
///
/// # Examples
/// ```
/// use qwt::QWT256;
///
/// let data = vec![1u8, 0, 1, 0, 2, 4, 5, 3];
///
/// let qwt = QWT256::from(data);
///
/// assert_eq!(qwt.len(), 8);
/// ```
pub fn len(&self) -> usize {
self.n
}
/// Returns the largest value in the sequence. Note: it is not +1 because it may overflow.
pub fn sigma(&self) -> T {
self.sigma
}
/// Checks if the indexed sequence is empty.
///
/// # Examples
/// ```
/// use qwt::QWT256;
///
/// let qwt = QWT256::<u8>::default();
///
/// assert_eq!(qwt.is_empty(), true);
/// ```
pub fn is_empty(&self) -> bool {
self.n == 0
}
/// Returns the number of levels in the wavelet tree.
pub fn n_levels(&self) -> usize {
self.n_levels
}
/// Returns an iterator over the values in the wavelet tree.
///
/// # Examples
///
/// ```
/// use qwt::QWT256;
///
/// let data: Vec<u8> = (0..10u8).into_iter().cycle().take(100).collect();
///
/// let qwt = QWT256::from(data);
///
/// for (i, v) in qwt.iter().enumerate() {
/// assert_eq!((i%10) as u8, v);
/// }
/// ```
pub fn iter(
&self,
) -> QWTIterator<T, RS, &QWaveletTree<T, RS, WITH_PREFETCH_SUPPORT>, WITH_PREFETCH_SUPPORT>
{
QWTIterator {
i: 0,
qwt: self,
_phantom: PhantomData,
}
}
#[inline]
unsafe fn rank_prefetch_superblocks_unchecked(&self, symbol: T, i: usize) -> usize {
if !WITH_PREFETCH_SUPPORT {
return 0;
}
if let Some(ref prefetch_support) = self.prefetch_support {
let mut shift: i64 = (2 * (self.n_levels - 1)) as i64;
let mut range = 0..i;
//let mut real_range = 0..i;
self.qvs[0].prefetch_data(range.end);
self.qvs[0].prefetch_info(range.start);
self.qvs[0].prefetch_info(range.end);
#[allow(clippy::needless_range_loop)]
for level in 0..self.n_levels - 1 {
let two_bits: u8 = (symbol >> shift as usize).as_() & 3;
// SAFETY: Here we are sure that two_bits is a symbol in [0..3]
let offset = self.qvs[level].occs_smaller_unchecked(two_bits);
let rank_start =
prefetch_support[level].approx_rank_unchecked(two_bits, range.start);
let rank_end = prefetch_support[level].approx_rank_unchecked(two_bits, range.end);
range = (rank_start + offset)..(rank_end + offset);
self.qvs[level + 1].prefetch_info(range.start);
self.qvs[level + 1].prefetch_info(range.start + 2048);
self.qvs[level + 1].prefetch_info(range.end);
self.qvs[level + 1].prefetch_info(range.end + 2048);
if level > 0 {
self.qvs[level + 1].prefetch_info(range.start + 2 * 2048);
self.qvs[level + 1].prefetch_info(range.end + 2 * 2048);
self.qvs[level + 1].prefetch_info(range.end + 3 * 2048);
}
// self.qvs[level + 1].prefetch_info(range.end + 4 * 2048);
// // CHECK!
// let rank_start = self.qvs[level].rank_unchecked(two_bits, real_range.start);
// let rank_end = self.qvs[level].rank_unchecked(two_bits, real_range.end);
// real_range = (rank_start + offset)..(rank_end + offset);
// //if range.start > real_range.start || range.end > real_range.end {
// // println!("Happen this");
// // }
// if range.start / 2048 != real_range.start / 2048
// && range.start / 2048 + 1 != real_range.start / 2048
// && range.start / 2048 + 2 != real_range.start / 2048
// {
// println!("Level: {}", level);
// println!("Real range.start: {:?}", real_range);
// println!("Appr range.start: {:?}", range);
// println!("real_range.start / 2048: {}", real_range.start / 2048);
// println!("approx range.start / 2048: {}\n", range.start / 2048);
// }
// if range.end / 2048 != real_range.end / 2048
// && range.end / 2048 + 1 != real_range.end / 2048
// && range.end / 2048 + 2 != real_range.end / 2048
// && range.end / 2048 + 3 != real_range.end / 2048
// {
// println!("Level: {}", level);
// println!("Real range.end: {:?}", real_range);
// println!("Appr range.end: {:?}", range);
// println!("real_range.end / 2048: {}", real_range.end / 2048);
// println!("approx range.end / 2048: {}\n", range.end / 2048);
// }
shift -= 2;
}
return range.end - range.start;
}
0
}
/// Returns rank of `symbol` up to position `i` **excluded**.
/// `None`, is returned if `i` is out of bound or if `symbol`
/// is not valid (i.e., it is greater than or equal to the alphabet size).
///
/// Differently from `rank` function, it runs a first phase
/// in which it estimates the positions in the wavelet tree
/// needed by rank queries and prefetches these data.
/// It is faster than the original rank whenever the superblock/block
/// counters fit in L3 cache but the sequence is larger.
///
/// # Examples
/// ```
/// use qwt::{QWT256, RankUnsigned};
///
/// let data = vec![1u8, 0, 1, 0, 2, 4, 5, 3];
///
/// let qwt = QWT256::from(data);
///
/// assert_eq!(qwt.rank_prefetch(1, 2), Some(1));
/// assert_eq!(qwt.rank_prefetch(3, 8), Some(1));
/// assert_eq!(qwt.rank_prefetch(1, 0), Some(0));
/// assert_eq!(qwt.rank_prefetch(1, 9), None); // too large position
/// assert_eq!(qwt.rank_prefetch(6, 1), None); // too large symbol
/// ```
#[inline(always)]
pub fn rank_prefetch(&self, symbol: T, i: usize) -> Option<usize> {
if i > self.n || symbol > self.sigma {
return None;
}
// SAFETY: Check the above guarantees we are not out of bound
Some(unsafe { self.rank_prefetch_unchecked(symbol, i) })
}
#[inline(always)]
/// Returns rank of `symbol` up to position `i` **excluded**.
/// Differently from `rank_unchecked`, it runs a first phase
/// in which it estimates the positions in the wavelet tree
/// needed by rank queries and prefetches these data.
/// It is faster than the original rank whenever the superblock/block
/// counters fit in L3 cache but the sequence is larger.
///
/// # Safety
/// Calling this method with a position `i` larger than the size of the sequence
/// of with invalid symbol is undefined behavior.
///
/// # Examples
/// ```
/// use qwt::{QWT256, RankUnsigned};
///
/// let data = vec![1u8, 0, 1, 0, 2, 4, 5, 3];
///
/// let qwt = QWT256::from(data);
///
/// unsafe {
/// assert_eq!(qwt.rank_prefetch_unchecked(1, 2), 1);
/// }
/// ```
pub unsafe fn rank_prefetch_unchecked(&self, symbol: T, i: usize) -> usize {
if WITH_PREFETCH_SUPPORT {
let _ = self.rank_prefetch_superblocks_unchecked(symbol, i);
}
let mut range = 0..i;
let mut shift: i64 = (2 * (self.n_levels - 1)) as i64;
const BLOCK_SIZE: usize = 256; // TODO: fix me!
//let mut real_range = 0..i;
self.qvs[0].prefetch_data(range.start);
self.qvs[0].prefetch_data(range.end);
for level in 0..self.n_levels - 1 {
let two_bits: u8 = (symbol >> shift as usize).as_() & 3;
// SAFETY: Here we are sure that two_bits is a symbol in [0..3]
let offset = self.qvs[level].occs_smaller_unchecked(two_bits);
let rank_start = self.qvs[level].rank_block_unchecked(two_bits, range.start);
let rank_end = self.qvs[level].rank_block_unchecked(two_bits, range.end);
range = (rank_start + offset)..(rank_end + offset);
// The estimated position can be off by BLOCK_SIZE for every level
self.qvs[level + 1].prefetch_data(range.start);
self.qvs[level + 1].prefetch_data(range.start + BLOCK_SIZE);
self.qvs[level + 1].prefetch_data(range.end);
self.qvs[level + 1].prefetch_data(range.end + BLOCK_SIZE);
for i in 0..level {
self.qvs[level + 1].prefetch_data(range.end + 2 * BLOCK_SIZE + i * BLOCK_SIZE);
}
// // CHECK!
// let rank_start = self.qvs[level].rank_unchecked(two_bits, real_range.start);
// let rank_end = self.qvs[level].rank_unchecked(two_bits, real_range.end);
// real_range = (rank_start + offset)..(rank_end + offset);
// //if range.start > real_range.start || range.end > real_range.end {
// // // THIS NEVER HAPPEN!
// // }
// if range.start / 256 != real_range.start / 256
// && range.start / 256 + 1 != real_range.start / 256
// {
// println!("Level: {}", level);
// println!("Real range.start: {:?}", real_range);
// println!("Appr range.start: {:?}", range);
// println!("real_range.start / 256: {}", real_range.start / 256);
// println!("approx range.start / 256: {}\n", range.start / 256);
// }
// if !(range.end / 256 <= real_range.end / 256
// && range.end / 256 + level + 1 >= real_range.end / 256)
// {
// println!("{}", range.end / 256 <= real_range.end / 256);
// println!("{}", range.end / 256 + level + 1 >= real_range.end / 256);
// println!("{}", range.end / 256 + level >= real_range.end / 256);
// println!("{}", range.end / 256 <= real_range.end / 256);
// println!("Level: {}", level);
// println!("Real range.end: {:?}", real_range);
// println!("Appr range.end: {:?}", range);
// println!("real_range.end / 256: {}", real_range.end / 256);
// println!("approx range.end / 256: {}\n", range.end / 256);
// }
shift -= 2;
}
self.rank_unchecked(symbol, i)
}
}
impl<T, RS, const WITH_PREFETCH_SUPPORT: bool> RankUnsigned
for QWaveletTree<T, RS, WITH_PREFETCH_SUPPORT>
where
T: WTIndexable,
u8: AsPrimitive<T>,
RS: RSforWT,
{
/// Returns rank of `symbol` up to position `i` **excluded**.
/// `None`, is returned if `i` is out of bound or if `symbol`
/// is not valid (i.e., it is greater than or equal to the alphabet size).
///
/// # Examples
/// ```
/// use qwt::{QWT256, RankUnsigned};
///
/// let data = vec![1u8, 0, 1, 0, 2, 4, 5, 3];
///
/// let qwt = QWT256::from(data);
///
/// assert_eq!(qwt.rank(1, 2), Some(1));
/// assert_eq!(qwt.rank(3, 8), Some(1));
/// assert_eq!(qwt.rank(1, 0), Some(0));
/// assert_eq!(qwt.rank(1, 9), None); // too large position
/// assert_eq!(qwt.rank(6, 1), None); // too large symbol
/// ```
#[inline(always)]
fn rank(&self, symbol: Self::Item, i: usize) -> Option<usize> {
if i > self.n || symbol > self.sigma {
return None;
}
// SAFETY: Check above guarantees we are not out of bound
Some(unsafe { self.rank_unchecked(symbol, i) })
}
/// Returns rank of `symbol` up to position `i` **excluded**.
///
/// # Safety
/// Calling this method with a position `i` larger than the size of the sequence
/// of with invalid symbol is undefined behavior.
///
/// # Examples
/// ```
/// use qwt::{QWT256, RankUnsigned};
///
/// let data = vec![1u8, 0, 1, 0, 2, 4, 5, 3];
///
/// let qwt = QWT256::from(data);
///
/// unsafe {
/// assert_eq!(qwt.rank_unchecked(1, 2), 1);
/// }
/// ```
#[inline(always)]
unsafe fn rank_unchecked(&self, symbol: Self::Item, i: usize) -> usize {
let mut shift: i64 = (2 * (self.n_levels - 1)) as i64;
let mut cur_i = i;
let mut cur_p = 0;
for level in 0..self.n_levels - 1 {
let two_bits: u8 = (symbol >> shift as usize).as_() & 3;
// Safety: Here we are sure that two_bits is a symbol in [0..3]
let offset = unsafe { self.qvs[level].occs_smaller_unchecked(two_bits) };
cur_p = self.qvs[level].rank_unchecked(two_bits, cur_p) + offset;
cur_i = self.qvs[level].rank_unchecked(two_bits, cur_i) + offset;
shift -= 2;
}
let two_bits: u8 = (symbol >> shift as usize).as_() & 3;
cur_i = self.qvs[self.n_levels - 1].rank_unchecked(two_bits, cur_i);
cur_p = self.qvs[self.n_levels - 1].rank_unchecked(two_bits, cur_p);
cur_i - cur_p
}
}
impl<T, RS, const WITH_PREFETCH_SUPPORT: bool> AccessUnsigned
for QWaveletTree<T, RS, WITH_PREFETCH_SUPPORT>
where
T: WTIndexable,
u8: AsPrimitive<T>,
RS: RSforWT,
{
type Item = T;
/// Returns the `i`-th symbol of the indexed sequence, `None` is returned if `i` is out of bound.
///
/// # Examples
/// ```
/// use qwt::{QWT256, AccessUnsigned};
///
/// let data = vec![1u8, 0, 1, 0, 2, 4, 5, 3];
///
/// let qwt = QWT256::from(data);
///
/// assert_eq!(qwt.get(2), Some(1));
/// assert_eq!(qwt.get(3), Some(0));
/// assert_eq!(qwt.get(8), None);
/// ```
///
/// ```
/// use qwt::{QWT256, AccessUnsigned, RankUnsigned, SelectUnsigned};
///
/// let data = vec![1u32, 0, 1, 0, 2, 1000000, 5, 3];
/// let qwt = QWT256::from(data);
///
/// assert_eq!(qwt.get(2), Some(1));
/// assert_eq!(qwt.get(5), Some(1000000));
/// assert_eq!(qwt.get(8), None);
/// ```
#[inline(always)]
fn get(&self, i: usize) -> Option<Self::Item> {
if i >= self.n {
return None;
}
// SAFETY: check before guarantees we are not out of bound
Some(unsafe { self.get_unchecked(i) })
}
/// Returns the `i`-th symbol of the indexed sequence.
///
/// # Safety
/// Calling this method with an out-of-bounds index is undefined behavior.
///
/// # Examples
/// ```
/// use qwt::{QWT256, AccessUnsigned};
///
/// let data = vec![1u8, 0, 1, 0, 2, 4, 5, 3];
///
/// let qwt = QWT256::from(data);
///
/// unsafe {
/// assert_eq!(qwt.get_unchecked(2), 1);
/// assert_eq!(qwt.get_unchecked(3), 0);
/// }
/// ```
#[inline(always)]
unsafe fn get_unchecked(&self, i: usize) -> Self::Item {
let mut result = T::zero();
let mut cur_i = i;
for level in 0..self.n_levels - 1 {
// The last rank can be saved. The improvement is just ~3%. Indeed, most of the cost is for the cache miss for data access that we pay anyway
self.qvs[level].prefetch_info(cur_i); // Compiler is not able to infer that later it is needed for the rank query. Access is roughly 33% slower for large files without this.
let symbol = self.qvs[level].get_unchecked(cur_i);
result = (result << 2) | symbol.as_();
// SAFETY: Here we are sure that symbol is in [0..3]
let offset = unsafe { self.qvs[level].occs_smaller_unchecked(symbol) };
cur_i = self.qvs[level].rank_unchecked(symbol, cur_i) + offset;
}
let symbol = self.qvs[self.n_levels - 1].get_unchecked(cur_i);
(result << 2) | symbol.as_()
}
}
impl<T, RS, const WITH_PREFETCH_SUPPORT: bool> SelectUnsigned
for QWaveletTree<T, RS, WITH_PREFETCH_SUPPORT>
where
T: WTIndexable,
u8: AsPrimitive<T>,
RS: RSforWT,
{
/// Returns the position of the `i`-th occurrence of symbol `symbol`, `None` is
/// returned if i is 0 or if there is no such occurrence for the symbol or if
/// `symbol` is not valid (i.e., it is greater than or equal to the alphabet size).
///
/// # Examples
/// ```
/// use qwt::{QWT256, SelectUnsigned};
///
/// let data = vec![1u8, 0, 1, 0, 2, 4, 5, 3];
///
/// let qwt = QWT256::from(data);
///
/// assert_eq!(qwt.select(1, 1), Some(0));
/// assert_eq!(qwt.select(0, 2), Some(3));
/// assert_eq!(qwt.select(1, 0), None);
/// assert_eq!(qwt.select(6, 1), None);
/// ```
#[inline(always)]
fn select(&self, symbol: Self::Item, i: usize) -> Option<usize> {
if i == 0 || symbol > self.sigma {
return None;
}
let mut path_off = Vec::with_capacity(self.n_levels);
let mut rank_path_off = Vec::with_capacity(self.n_levels);
let mut b = 0;
let mut shift: i64 = 2 * (self.n_levels - 1) as i64;
for level in 0..self.n_levels {
path_off.push(b);
let two_bits = (symbol >> shift as usize).as_() & 3;
let rank_b = self.qvs[level].rank(two_bits, b)?;
// Safety: we are sure the symbol `two_bits` is in [0..3]
b = rank_b + unsafe { self.qvs[level].occs_smaller_unchecked(two_bits) };
shift -= 2;
rank_path_off.push(rank_b);
}
shift = 0;
let mut result = i;
for level in (0..self.n_levels).rev() {
b = path_off[level];
let rank_b = rank_path_off[level];
let two_bits = (symbol >> shift as usize).as_() & 3;
result = self.qvs[level].select(two_bits, rank_b + result)? - b + 1;
shift += 2;
}
Some(result - 1)
}
/// Returns the position of the `i`-th occurrence of symbol `symbol`.
///
/// # Safety
/// Calling this method with a value of `i` which is larger than the number of
/// occurrences of the `symbol` or if the `symbol` is not valid is undefined behavior.
///
/// In the current implementation there is no reason to prefer this unsafe select
/// over the safe one.
#[inline(always)]
unsafe fn select_unchecked(&self, symbol: Self::Item, i: usize) -> usize {
self.select(symbol, i).unwrap()
}
}
impl<T, RS: SpaceUsage, const WITH_PREFETCH_SUPPORT: bool> SpaceUsage
for QWaveletTree<T, RS, WITH_PREFETCH_SUPPORT>
{
/// Gives the space usage in bytes of the struct.
fn space_usage_byte(&self) -> usize {
let space_prefetch_support: usize = self
.prefetch_support
.iter()
.flatten()
.map(|ps| ps.space_usage_byte())
.sum();
8 + 8
+ self
.qvs
.iter()
.fold(0, |acc, ds| acc + ds.space_usage_byte())
+ space_prefetch_support
}
}
impl<T, RS, const WITH_PREFETCH_SUPPORT: bool> AsRef<QWaveletTree<T, RS, WITH_PREFETCH_SUPPORT>>
for QWaveletTree<T, RS, WITH_PREFETCH_SUPPORT>
{
fn as_ref(&self) -> &QWaveletTree<T, RS, WITH_PREFETCH_SUPPORT> {
self
}
}
// This is a naive implementation of an iterator for WT.
// We could do better by storing more information and
// avoid rank operations!
#[derive(Debug, PartialEq)]
pub struct QWTIterator<
T,
RS,
Q: AsRef<QWaveletTree<T, RS, WITH_PREFETCH_SUPPORT>>,
const WITH_PREFETCH_SUPPORT: bool = false,
> {
i: usize,
qwt: Q,
_phantom: PhantomData<(T, RS)>,
}
impl<
T,
RS,
Q: AsRef<QWaveletTree<T, RS, WITH_PREFETCH_SUPPORT>>,
const WITH_PREFETCH_SUPPORT: bool,
> Iterator for QWTIterator<T, RS, Q, WITH_PREFETCH_SUPPORT>
where
T: WTIndexable,
u8: AsPrimitive<T>,
RS: RSforWT,
{
type Item = T;
fn next(&mut self) -> Option<Self::Item> {
// TODO: this may be faster without calling get.
let qwt = self.qwt.as_ref();
self.i += 1;
qwt.get(self.i - 1)
}
}
impl<T, RS, const WITH_PREFETCH_SUPPORT: bool> IntoIterator
for QWaveletTree<T, RS, WITH_PREFETCH_SUPPORT>
where
T: WTIndexable,
u8: AsPrimitive<T>,
RS: RSforWT,
{
type IntoIter =
QWTIterator<T, RS, QWaveletTree<T, RS, WITH_PREFETCH_SUPPORT>, WITH_PREFETCH_SUPPORT>;
type Item = T;
fn into_iter(self) -> Self::IntoIter {
QWTIterator {
i: 0,
qwt: self,
_phantom: PhantomData,
}
}
}
impl<'a, T, RS, const WITH_PREFETCH_SUPPORT: bool> IntoIterator
for &'a QWaveletTree<T, RS, WITH_PREFETCH_SUPPORT>
where
T: WTIndexable,
u8: AsPrimitive<T>,
RS: RSforWT,
{
type IntoIter =
QWTIterator<T, RS, &'a QWaveletTree<T, RS, WITH_PREFETCH_SUPPORT>, WITH_PREFETCH_SUPPORT>;
type Item = T;
fn into_iter(self) -> Self::IntoIter {
self.iter()
}
}
impl<T, RS, const WITH_PREFETCH_SUPPORT: bool> FromIterator<T>
for QWaveletTree<T, RS, WITH_PREFETCH_SUPPORT>
where
T: WTIndexable,
u8: AsPrimitive<T>,
RS: RSforWT,
{
fn from_iter<I>(iter: I) -> Self
where
I: IntoIterator<Item = T>,
{
QWaveletTree::new(&mut iter.into_iter().collect::<Vec<T>>())
}
}
impl<T, RS, const WITH_PREFETCH_SUPPORT: bool> From<Vec<T>>
for QWaveletTree<T, RS, WITH_PREFETCH_SUPPORT>
where
T: WTIndexable,
u8: AsPrimitive<T>,
RS: RSforWT,
{
fn from(mut v: Vec<T>) -> Self {
QWaveletTree::new(&mut v[..])
}
}
#[cfg(test)]
mod tests;