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//! If part of the iterators outputs are disjoint increasing integer intervals,
//! then the iterators can be zipped together and the iteration can proceeds at
//! the granularity of the common refinements of all the integer intervals.
use crate::{
interval::{traits::Interval, IntInterval},
set::traits::Intersect,
};
use num::{Integer, Num, ToPrimitive};
use std::{
collections::BTreeSet,
marker::{PhantomData, Sized},
};
pub trait CommonRefinementZip<B, X, P, V>
where
B: Copy + Num + Ord,
Self: Iterator<Item = X> + Sized,
P: Clone + Interval<B> + for<'b> Intersect<&'b P, Option<P>>, {
fn get_interval_value_extractor(
&self,
) -> Box<dyn Fn(<Self as Iterator>::Item) -> (P, V)>;
fn common_refinement_zip(
mut self,
mut other: Self,
) -> CommonRefinementZipped<B, Self, X, P, V> {
let extractor = self.get_interval_value_extractor();
let mut intervals = Vec::new();
let mut values = Vec::new();
match self.next() {
None => {
intervals.push(None);
values.push(None);
}
Some(x) => {
let (interval, value) = extractor(x);
intervals.push(Some(interval));
values.push(Some(value));
}
}
match other.next() {
None => {
intervals.push(None);
values.push(None);
}
Some(x) => {
let (interval, value) = extractor(x);
intervals.push(Some(interval));
values.push(Some(value));
}
}
CommonRefinementZipped {
iters: vec![self, other],
intervals,
values,
extractor,
phantom: PhantomData,
}
}
fn into_common_refinement_zipped(
mut self,
) -> CommonRefinementZipped<B, Self, X, P, V> {
let extractor = self.get_interval_value_extractor();
let mut intervals = Vec::new();
let mut values = Vec::new();
match self.next() {
None => {
intervals.push(None);
values.push(None);
}
Some(x) => {
let (interval, value) = extractor(x);
intervals.push(Some(interval));
values.push(Some(value));
}
}
CommonRefinementZipped {
iters: vec![self],
intervals,
values,
extractor,
phantom: PhantomData,
}
}
}
/// # Example
/// ```
/// use math::{
/// interval::{traits::Interval, IntInterval},
/// iter::CommonRefinementZip,
/// };
/// use std::collections::BTreeMap;
///
/// let m1: BTreeMap<IntInterval<usize>, i32> =
/// vec![(IntInterval::new(0, 5), 5), (IntInterval::new(8, 10), 2)]
/// .into_iter()
/// .collect();
///
/// let m2: BTreeMap<IntInterval<usize>, i32> =
/// vec![(IntInterval::new(2, 4), 8), (IntInterval::new(12, 13), 9)]
/// .into_iter()
/// .collect();
///
/// let mut iter = m1.iter().common_refinement_zip(m2.iter());
/// assert_eq!(
/// Some((IntInterval::new(0, 1), vec![Some(5), None])),
/// iter.next()
/// );
/// assert_eq!(
/// Some((IntInterval::new(2, 4), vec![Some(5), Some(8)])),
/// iter.next()
/// );
/// assert_eq!(
/// Some((IntInterval::new(5, 5), vec![Some(5), None])),
/// iter.next()
/// );
/// assert_eq!(
/// Some((IntInterval::new(8, 10), vec![Some(2), None])),
/// iter.next()
/// );
/// assert_eq!(
/// Some((IntInterval::new(12, 13), vec![None, Some(9)])),
/// iter.next()
/// );
/// assert_eq!(None, iter.next());
/// ```
impl<'a, V, B: Integer + Copy + ToPrimitive>
CommonRefinementZip<B, (&'a IntInterval<B>, &'a V), IntInterval<B>, V>
for std::collections::btree_map::Iter<'a, IntInterval<B>, V>
where
B: 'a,
V: 'a + Clone,
{
fn get_interval_value_extractor(
&self,
) -> Box<dyn Fn(<Self as Iterator>::Item) -> (IntInterval<B>, V)> {
Box::new(|item| ((*item.0).clone(), (*item.1).clone()))
}
}
impl<'a, V, B: Integer + Copy + ToPrimitive>
CommonRefinementZip<B, (IntInterval<B>, V), IntInterval<B>, V>
for std::collections::btree_map::IntoIter<IntInterval<B>, V>
where
B: 'a,
{
fn get_interval_value_extractor(
&self,
) -> Box<dyn Fn(<Self as Iterator>::Item) -> (IntInterval<B>, V)> {
Box::new(|item| (item.0, item.1))
}
}
/// # Iterator Algorithm Description
/// Given a list of iterators, a list of the current minimum interval for each
/// iterator will be maintained together with their associated values. Then, at
/// each pass the smallest minimum common refinement of the current intervals is
/// subtracted from each interval. A list of values will be returned along with
/// the common refinement. Each value will be the value associated with the
/// iterated interval if the common refinement has a non-empty intersection with
/// the corresponding interval, and `None` otherwise.
///
/// If an interval becomes empty after the subtraction, the corresponding
/// iterator will be called to replace the interval with the next interval,
/// together with the associated values.
///
/// # Fields
/// * `iters`: the list of zipped iterators.
/// * `intervals`: the intervals assocaited with each iterator for the current
/// pass.
/// * `values`: the values associated with each iterator for the current pass.
/// * `extractor`: a function that extracts a tuple of (interval, value) from
/// each of the items yielded from the iterators.
pub struct CommonRefinementZipped<B, I, X, P, V>
where
B: Copy + Num + Ord,
I: Iterator<Item = X> + Sized,
P: Clone + Interval<B> + for<'b> Intersect<&'b P, Option<P>>, {
iters: Vec<I>,
intervals: Vec<Option<P>>,
values: Vec<Option<V>>,
extractor: Box<dyn Fn(X) -> (P, V)>,
phantom: PhantomData<B>,
}
impl<B, I, X, P, V> Iterator for CommonRefinementZipped<B, I, X, P, V>
where
B: Copy + Num + Ord,
I: Iterator<Item = X> + Sized,
P: Clone + Interval<B> + for<'b> Intersect<&'b P, Option<P>>,
V: Clone,
{
type Item = (P, Vec<Option<V>>);
fn next(&mut self) -> Option<Self::Item> {
let starts: BTreeSet<B> = self
.intervals
.iter()
.filter_map(|i| i.clone().and_then(|i| Some(i.get_start())))
.collect();
let ends: BTreeSet<B> = self
.intervals
.iter()
.filter_map(|i| i.clone().and_then(|i| Some(i.get_end())))
.collect();
let mut starts_iter = starts.iter();
let min_start = match starts_iter.next() {
// if all intervals are empty, it means that all the iterators have
// been exhausted
None => return None,
Some(&a) => a,
};
let second_min_start = starts_iter.next();
let min_end = *ends.iter().next().unwrap();
let min_refinement = match second_min_start {
Some(&second_min_start) => {
if second_min_start <= min_end {
P::from_boundaries(min_start, second_min_start - B::one())
} else {
P::from_boundaries(min_start, min_end)
}
}
None => P::from_boundaries(min_start, min_end),
};
let mut refinement_values = Vec::new();
for ((interval, iter), v) in self
.intervals
.iter_mut()
.zip(self.iters.iter_mut())
.zip(self.values.iter_mut())
{
match interval {
Some(i) => {
if i.has_non_empty_intersection_with(&min_refinement) {
refinement_values.push((*v).clone());
// subtract the min_refinement from the interval
// min_start <= i.get_start() <= min_end <= i.get_end()
let remainder = P::from_boundaries(
min_refinement.get_end() + B::one(),
i.get_end(),
);
if remainder.is_empty() {
match iter.next() {
None => {
*interval = None;
*v = None;
}
Some(x) => {
let (new_interval, new_val) =
(self.extractor)(x);
*interval = Some(new_interval);
*v = Some(new_val);
}
}
} else {
*interval = Some(remainder);
}
} else {
refinement_values.push(None);
}
}
None => {
refinement_values.push(None);
}
}
}
Some((min_refinement, refinement_values))
}
}
impl<B, I, X, P, V> CommonRefinementZipped<B, I, X, P, V>
where
B: Copy + Num + Ord,
I: Iterator<Item = X> + Sized,
P: Clone + Interval<B> + for<'b> Intersect<&'b P, Option<P>>,
{
/// ```
/// use math::{
/// interval::{traits::Interval, IntInterval},
/// iter::CommonRefinementZip,
/// };
/// use std::collections::BTreeMap;
///
/// let m1: BTreeMap<IntInterval<usize>, i32> =
/// vec![(IntInterval::new(0, 10), 5), (IntInterval::new(16, 17), 21)]
/// .into_iter()
/// .collect();
///
/// let m2: BTreeMap<IntInterval<usize>, i32> =
/// vec![(IntInterval::new(2, 3), 8), (IntInterval::new(12, 20), 9)]
/// .into_iter()
/// .collect();
///
/// let m3: BTreeMap<IntInterval<usize>, i32> = vec![
/// (IntInterval::new(2, 4), 7),
/// (IntInterval::new(9, 10), -1),
/// (IntInterval::new(15, 20), 0),
/// ]
/// .into_iter()
/// .collect();
///
/// let mut iter = m1
/// .iter()
/// .common_refinement_zip(m2.iter())
/// .common_refinement_flat_zip(m3.iter());
///
/// assert_eq!(
/// Some((IntInterval::new(0, 1), vec![Some(5), None, None])),
/// iter.next()
/// );
/// assert_eq!(
/// Some((IntInterval::new(2, 3), vec![Some(5), Some(8), Some(7)])),
/// iter.next()
/// );
/// assert_eq!(
/// Some((IntInterval::new(4, 4), vec![Some(5), None, Some(7)])),
/// iter.next()
/// );
/// assert_eq!(
/// Some((IntInterval::new(5, 8), vec![Some(5), None, None])),
/// iter.next()
/// );
/// assert_eq!(
/// Some((IntInterval::new(9, 10), vec![Some(5), None, Some(-1)])),
/// iter.next()
/// );
/// assert_eq!(
/// Some((IntInterval::new(12, 14), vec![None, Some(9), None])),
/// iter.next()
/// );
/// assert_eq!(
/// Some((IntInterval::new(15, 15), vec![None, Some(9), Some(0)])),
/// iter.next()
/// );
/// assert_eq!(
/// Some((IntInterval::new(16, 17), vec![Some(21), Some(9), Some(0)])),
/// iter.next()
/// );
/// assert_eq!(
/// Some((IntInterval::new(18, 20), vec![None, Some(9), Some(0)])),
/// iter.next()
/// );
/// assert_eq!(None, iter.next());
/// ```
pub fn common_refinement_flat_zip(
mut self,
mut other: I,
) -> CommonRefinementZipped<B, I, X, P, V>
where
I: Iterator<Item = X> + Sized, {
match other.next() {
None => {
self.intervals.push(None);
self.values.push(None);
}
Some(x) => {
let (i, v) = (self.extractor)(x);
self.intervals.push(Some(i.clone()));
self.values.push(Some(v));
}
}
self.iters.push(other);
CommonRefinementZipped {
iters: self.iters,
intervals: self.intervals,
values: self.values,
extractor: self.extractor,
phantom: PhantomData,
}
}
}