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use super::plumbing::*;
use super::*;
use std::cmp;
/// `MinLen` is an iterator that imposes a minimum length on iterator splits.
/// This struct is created by the [`with_min_len()`] method on [`IndexedParallelIterator`]
///
/// [`with_min_len()`]: trait.IndexedParallelIterator.html#method.with_min_len
/// [`IndexedParallelIterator`]: trait.IndexedParallelIterator.html
#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
#[derive(Debug, Clone)]
pub struct MinLen<I: IndexedParallelIterator> {
base: I,
min: usize,
}
impl<I> MinLen<I>
where
I: IndexedParallelIterator,
{
/// Creates a new `MinLen` iterator.
pub(super) fn new(base: I, min: usize) -> Self {
MinLen { base, min }
}
}
impl<I> ParallelIterator for MinLen<I>
where
I: IndexedParallelIterator,
{
type Item = I::Item;
fn drive_unindexed<C>(self, consumer: C) -> C::Result
where
C: UnindexedConsumer<Self::Item>,
{
bridge(self, consumer)
}
fn opt_len(&self) -> Option<usize> {
Some(self.len())
}
}
impl<I> IndexedParallelIterator for MinLen<I>
where
I: IndexedParallelIterator,
{
fn drive<C: Consumer<Self::Item>>(self, consumer: C) -> C::Result {
bridge(self, consumer)
}
fn len(&self) -> usize {
self.base.len()
}
fn with_producer<CB>(self, callback: CB) -> CB::Output
where
CB: ProducerCallback<Self::Item>,
{
return self.base.with_producer(Callback {
callback,
min: self.min,
});
struct Callback<CB> {
callback: CB,
min: usize,
}
impl<T, CB> ProducerCallback<T> for Callback<CB>
where
CB: ProducerCallback<T>,
{
type Output = CB::Output;
fn callback<P>(self, base: P) -> CB::Output
where
P: Producer<Item = T>,
{
let producer = MinLenProducer {
base,
min: self.min,
};
self.callback.callback(producer)
}
}
}
}
/// ////////////////////////////////////////////////////////////////////////
/// `MinLenProducer` implementation
struct MinLenProducer<P> {
base: P,
min: usize,
}
impl<P> Producer for MinLenProducer<P>
where
P: Producer,
{
type Item = P::Item;
type IntoIter = P::IntoIter;
fn into_iter(self) -> Self::IntoIter {
self.base.into_iter()
}
fn min_len(&self) -> usize {
cmp::max(self.min, self.base.min_len())
}
fn max_len(&self) -> usize {
self.base.max_len()
}
fn split_at(self, index: usize) -> (Self, Self) {
let (left, right) = self.base.split_at(index);
(
MinLenProducer {
base: left,
min: self.min,
},
MinLenProducer {
base: right,
min: self.min,
},
)
}
fn fold_with<F>(self, folder: F) -> F
where
F: Folder<Self::Item>,
{
self.base.fold_with(folder)
}
}
/// `MaxLen` is an iterator that imposes a maximum length on iterator splits.
/// This struct is created by the [`with_max_len()`] method on [`IndexedParallelIterator`]
///
/// [`with_max_len()`]: trait.IndexedParallelIterator.html#method.with_max_len
/// [`IndexedParallelIterator`]: trait.IndexedParallelIterator.html
#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
#[derive(Debug, Clone)]
pub struct MaxLen<I: IndexedParallelIterator> {
base: I,
max: usize,
}
impl<I> MaxLen<I>
where
I: IndexedParallelIterator,
{
/// Creates a new `MaxLen` iterator.
pub(super) fn new(base: I, max: usize) -> Self {
MaxLen { base, max }
}
}
impl<I> ParallelIterator for MaxLen<I>
where
I: IndexedParallelIterator,
{
type Item = I::Item;
fn drive_unindexed<C>(self, consumer: C) -> C::Result
where
C: UnindexedConsumer<Self::Item>,
{
bridge(self, consumer)
}
fn opt_len(&self) -> Option<usize> {
Some(self.len())
}
}
impl<I> IndexedParallelIterator for MaxLen<I>
where
I: IndexedParallelIterator,
{
fn drive<C: Consumer<Self::Item>>(self, consumer: C) -> C::Result {
bridge(self, consumer)
}
fn len(&self) -> usize {
self.base.len()
}
fn with_producer<CB>(self, callback: CB) -> CB::Output
where
CB: ProducerCallback<Self::Item>,
{
return self.base.with_producer(Callback {
callback,
max: self.max,
});
struct Callback<CB> {
callback: CB,
max: usize,
}
impl<T, CB> ProducerCallback<T> for Callback<CB>
where
CB: ProducerCallback<T>,
{
type Output = CB::Output;
fn callback<P>(self, base: P) -> CB::Output
where
P: Producer<Item = T>,
{
let producer = MaxLenProducer {
base,
max: self.max,
};
self.callback.callback(producer)
}
}
}
}
/// ////////////////////////////////////////////////////////////////////////
/// `MaxLenProducer` implementation
struct MaxLenProducer<P> {
base: P,
max: usize,
}
impl<P> Producer for MaxLenProducer<P>
where
P: Producer,
{
type Item = P::Item;
type IntoIter = P::IntoIter;
fn into_iter(self) -> Self::IntoIter {
self.base.into_iter()
}
fn min_len(&self) -> usize {
self.base.min_len()
}
fn max_len(&self) -> usize {
cmp::min(self.max, self.base.max_len())
}
fn split_at(self, index: usize) -> (Self, Self) {
let (left, right) = self.base.split_at(index);
(
MaxLenProducer {
base: left,
max: self.max,
},
MaxLenProducer {
base: right,
max: self.max,
},
)
}
fn fold_with<F>(self, folder: F) -> F
where
F: Folder<Self::Item>,
{
self.base.fold_with(folder)
}
}