148 lines
3.7 KiB
Rust
148 lines
3.7 KiB
Rust
use super::plumbing::*;
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use super::*;
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use std::fmt::{self, Debug};
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/// `FlatMapIter` maps each element to a serial iterator, then flattens these iterators together.
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/// This struct is created by the [`flat_map_iter()`] method on [`ParallelIterator`]
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///
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/// [`flat_map_iter()`]: trait.ParallelIterator.html#method.flat_map_iter
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/// [`ParallelIterator`]: trait.ParallelIterator.html
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#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
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#[derive(Clone)]
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pub struct FlatMapIter<I: ParallelIterator, F> {
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base: I,
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map_op: F,
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}
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impl<I: ParallelIterator + Debug, F> Debug for FlatMapIter<I, F> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.debug_struct("FlatMapIter")
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.field("base", &self.base)
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.finish()
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}
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}
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impl<I: ParallelIterator, F> FlatMapIter<I, F> {
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/// Creates a new `FlatMapIter` iterator.
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pub(super) fn new(base: I, map_op: F) -> Self {
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FlatMapIter { base, map_op }
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}
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}
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impl<I, F, SI> ParallelIterator for FlatMapIter<I, F>
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where
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I: ParallelIterator,
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F: Fn(I::Item) -> SI + Sync + Send,
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SI: IntoIterator,
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SI::Item: Send,
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{
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type Item = SI::Item;
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fn drive_unindexed<C>(self, consumer: C) -> C::Result
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where
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C: UnindexedConsumer<Self::Item>,
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{
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let consumer = FlatMapIterConsumer::new(consumer, &self.map_op);
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self.base.drive_unindexed(consumer)
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}
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}
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/// ////////////////////////////////////////////////////////////////////////
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/// Consumer implementation
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struct FlatMapIterConsumer<'f, C, F> {
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base: C,
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map_op: &'f F,
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}
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impl<'f, C, F> FlatMapIterConsumer<'f, C, F> {
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fn new(base: C, map_op: &'f F) -> Self {
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FlatMapIterConsumer { base, map_op }
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}
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}
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impl<'f, T, U, C, F> Consumer<T> for FlatMapIterConsumer<'f, C, F>
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where
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C: UnindexedConsumer<U::Item>,
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F: Fn(T) -> U + Sync,
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U: IntoIterator,
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{
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type Folder = FlatMapIterFolder<'f, C::Folder, F>;
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type Reducer = C::Reducer;
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type Result = C::Result;
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fn split_at(self, index: usize) -> (Self, Self, C::Reducer) {
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let (left, right, reducer) = self.base.split_at(index);
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(
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FlatMapIterConsumer::new(left, self.map_op),
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FlatMapIterConsumer::new(right, self.map_op),
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reducer,
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)
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}
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fn into_folder(self) -> Self::Folder {
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FlatMapIterFolder {
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base: self.base.into_folder(),
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map_op: self.map_op,
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}
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}
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fn full(&self) -> bool {
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self.base.full()
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}
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}
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impl<'f, T, U, C, F> UnindexedConsumer<T> for FlatMapIterConsumer<'f, C, F>
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where
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C: UnindexedConsumer<U::Item>,
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F: Fn(T) -> U + Sync,
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U: IntoIterator,
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{
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fn split_off_left(&self) -> Self {
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FlatMapIterConsumer::new(self.base.split_off_left(), self.map_op)
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}
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fn to_reducer(&self) -> Self::Reducer {
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self.base.to_reducer()
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}
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}
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struct FlatMapIterFolder<'f, C, F> {
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base: C,
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map_op: &'f F,
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}
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impl<'f, T, U, C, F> Folder<T> for FlatMapIterFolder<'f, C, F>
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where
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C: Folder<U::Item>,
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F: Fn(T) -> U,
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U: IntoIterator,
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{
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type Result = C::Result;
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fn consume(self, item: T) -> Self {
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let map_op = self.map_op;
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let base = self.base.consume_iter(map_op(item));
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FlatMapIterFolder { base, map_op }
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}
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fn consume_iter<I>(self, iter: I) -> Self
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where
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I: IntoIterator<Item = T>,
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{
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let map_op = self.map_op;
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let iter = iter.into_iter().flat_map(map_op);
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let base = self.base.consume_iter(iter);
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FlatMapIterFolder { base, map_op }
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}
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fn complete(self) -> Self::Result {
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self.base.complete()
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}
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fn full(&self) -> bool {
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self.base.full()
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}
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}
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