Source code
Revision control
Copy as Markdown
Other Tools
use super::plumbing::*;
use super::*;
use std::fmt::{self, Debug};
/// `Filter` takes a predicate `filter_op` and filters out elements that match.
/// This struct is created by the [`filter()`] method on [`ParallelIterator`]
///
/// [`filter()`]: trait.ParallelIterator.html#method.filter
/// [`ParallelIterator`]: trait.ParallelIterator.html
#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
#[derive(Clone)]
pub struct Filter<I: ParallelIterator, P> {
base: I,
filter_op: P,
}
impl<I: ParallelIterator + Debug, P> Debug for Filter<I, P> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("Filter").field("base", &self.base).finish()
}
}
impl<I, P> Filter<I, P>
where
I: ParallelIterator,
{
/// Creates a new `Filter` iterator.
pub(super) fn new(base: I, filter_op: P) -> Self {
Filter { base, filter_op }
}
}
impl<I, P> ParallelIterator for Filter<I, P>
where
I: ParallelIterator,
P: Fn(&I::Item) -> bool + Sync + Send,
{
type Item = I::Item;
fn drive_unindexed<C>(self, consumer: C) -> C::Result
where
C: UnindexedConsumer<Self::Item>,
{
let consumer1 = FilterConsumer::new(consumer, &self.filter_op);
self.base.drive_unindexed(consumer1)
}
}
/// ////////////////////////////////////////////////////////////////////////
/// Consumer implementation
struct FilterConsumer<'p, C, P> {
base: C,
filter_op: &'p P,
}
impl<'p, C, P> FilterConsumer<'p, C, P> {
fn new(base: C, filter_op: &'p P) -> Self {
FilterConsumer { base, filter_op }
}
}
impl<'p, T, C, P: 'p> Consumer<T> for FilterConsumer<'p, C, P>
where
C: Consumer<T>,
P: Fn(&T) -> bool + Sync,
{
type Folder = FilterFolder<'p, C::Folder, P>;
type Reducer = C::Reducer;
type Result = C::Result;
fn split_at(self, index: usize) -> (Self, Self, C::Reducer) {
let (left, right, reducer) = self.base.split_at(index);
(
FilterConsumer::new(left, self.filter_op),
FilterConsumer::new(right, self.filter_op),
reducer,
)
}
fn into_folder(self) -> Self::Folder {
FilterFolder {
base: self.base.into_folder(),
filter_op: self.filter_op,
}
}
fn full(&self) -> bool {
self.base.full()
}
}
impl<'p, T, C, P: 'p> UnindexedConsumer<T> for FilterConsumer<'p, C, P>
where
C: UnindexedConsumer<T>,
P: Fn(&T) -> bool + Sync,
{
fn split_off_left(&self) -> Self {
FilterConsumer::new(self.base.split_off_left(), self.filter_op)
}
fn to_reducer(&self) -> Self::Reducer {
self.base.to_reducer()
}
}
struct FilterFolder<'p, C, P> {
base: C,
filter_op: &'p P,
}
impl<'p, C, P, T> Folder<T> for FilterFolder<'p, C, P>
where
C: Folder<T>,
P: Fn(&T) -> bool + 'p,
{
type Result = C::Result;
fn consume(self, item: T) -> Self {
let filter_op = self.filter_op;
if filter_op(&item) {
let base = self.base.consume(item);
FilterFolder { base, filter_op }
} else {
self
}
}
// This cannot easily specialize `consume_iter` to be better than
// the default, because that requires checking `self.base.full()`
// during a call to `self.base.consume_iter()`. (#632)
fn complete(self) -> Self::Result {
self.base.complete()
}
fn full(&self) -> bool {
self.base.full()
}
}