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use super::plumbing::*;
use super::*;
use std::fmt::{self, Debug};
/// `FilterMap` creates an iterator that uses `filter_op` to both filter and map elements.
/// This struct is created by the [`filter_map()`] method on [`ParallelIterator`].
///
/// [`filter_map()`]: trait.ParallelIterator.html#method.filter_map
/// [`ParallelIterator`]: trait.ParallelIterator.html
#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
#[derive(Clone)]
pub struct FilterMap<I: ParallelIterator, P> {
base: I,
filter_op: P,
}
impl<I: ParallelIterator + Debug, P> Debug for FilterMap<I, P> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("FilterMap")
.field("base", &self.base)
.finish()
}
}
impl<I: ParallelIterator, P> FilterMap<I, P> {
/// Creates a new `FilterMap` iterator.
pub(super) fn new(base: I, filter_op: P) -> Self {
FilterMap { base, filter_op }
}
}
impl<I, P, R> ParallelIterator for FilterMap<I, P>
where
I: ParallelIterator,
P: Fn(I::Item) -> Option<R> + Sync + Send,
R: Send,
{
type Item = R;
fn drive_unindexed<C>(self, consumer: C) -> C::Result
where
C: UnindexedConsumer<Self::Item>,
{
let consumer = FilterMapConsumer::new(consumer, &self.filter_op);
self.base.drive_unindexed(consumer)
}
}
/// ////////////////////////////////////////////////////////////////////////
/// Consumer implementation
struct FilterMapConsumer<'p, C, P> {
base: C,
filter_op: &'p P,
}
impl<'p, C, P: 'p> FilterMapConsumer<'p, C, P> {
fn new(base: C, filter_op: &'p P) -> Self {
FilterMapConsumer { base, filter_op }
}
}
impl<'p, T, U, C, P> Consumer<T> for FilterMapConsumer<'p, C, P>
where
C: Consumer<U>,
P: Fn(T) -> Option<U> + Sync + 'p,
{
type Folder = FilterMapFolder<'p, C::Folder, P>;
type Reducer = C::Reducer;
type Result = C::Result;
fn split_at(self, index: usize) -> (Self, Self, Self::Reducer) {
let (left, right, reducer) = self.base.split_at(index);
(
FilterMapConsumer::new(left, self.filter_op),
FilterMapConsumer::new(right, self.filter_op),
reducer,
)
}
fn into_folder(self) -> Self::Folder {
let base = self.base.into_folder();
FilterMapFolder {
base,
filter_op: self.filter_op,
}
}
fn full(&self) -> bool {
self.base.full()
}
}
impl<'p, T, U, C, P> UnindexedConsumer<T> for FilterMapConsumer<'p, C, P>
where
C: UnindexedConsumer<U>,
P: Fn(T) -> Option<U> + Sync + 'p,
{
fn split_off_left(&self) -> Self {
FilterMapConsumer::new(self.base.split_off_left(), self.filter_op)
}
fn to_reducer(&self) -> Self::Reducer {
self.base.to_reducer()
}
}
struct FilterMapFolder<'p, C, P> {
base: C,
filter_op: &'p P,
}
impl<'p, T, U, C, P> Folder<T> for FilterMapFolder<'p, C, P>
where
C: Folder<U>,
P: Fn(T) -> Option<U> + Sync + 'p,
{
type Result = C::Result;
fn consume(self, item: T) -> Self {
let filter_op = self.filter_op;
if let Some(mapped_item) = filter_op(item) {
let base = self.base.consume(mapped_item);
FilterMapFolder { 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) -> C::Result {
self.base.complete()
}
fn full(&self) -> bool {
self.base.full()
}
}