1 use super::plumbing::*; 2 use super::*; 3 4 use std::fmt::{self, Debug}; 5 6 /// `FlatMapIter` maps each element to a serial iterator, then flattens these iterators together. 7 /// This struct is created by the [`flat_map_iter()`] method on [`ParallelIterator`] 8 /// 9 /// [`flat_map_iter()`]: trait.ParallelIterator.html#method.flat_map_iter 10 /// [`ParallelIterator`]: trait.ParallelIterator.html 11 #[must_use = "iterator adaptors are lazy and do nothing unless consumed"] 12 #[derive(Clone)] 13 pub struct FlatMapIter<I: ParallelIterator, F> { 14 base: I, 15 map_op: F, 16 } 17 18 impl<I: ParallelIterator + Debug, F> Debug for FlatMapIter<I, F> { fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result19 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { 20 f.debug_struct("FlatMapIter") 21 .field("base", &self.base) 22 .finish() 23 } 24 } 25 26 impl<I: ParallelIterator, F> FlatMapIter<I, F> { 27 /// Creates a new `FlatMapIter` iterator. new(base: I, map_op: F) -> Self28 pub(super) fn new(base: I, map_op: F) -> Self { 29 FlatMapIter { base, map_op } 30 } 31 } 32 33 impl<I, F, SI> ParallelIterator for FlatMapIter<I, F> 34 where 35 I: ParallelIterator, 36 F: Fn(I::Item) -> SI + Sync + Send, 37 SI: IntoIterator, 38 SI::Item: Send, 39 { 40 type Item = SI::Item; 41 drive_unindexed<C>(self, consumer: C) -> C::Result where C: UnindexedConsumer<Self::Item>,42 fn drive_unindexed<C>(self, consumer: C) -> C::Result 43 where 44 C: UnindexedConsumer<Self::Item>, 45 { 46 let consumer = FlatMapIterConsumer::new(consumer, &self.map_op); 47 self.base.drive_unindexed(consumer) 48 } 49 } 50 51 /// //////////////////////////////////////////////////////////////////////// 52 /// Consumer implementation 53 54 struct FlatMapIterConsumer<'f, C, F> { 55 base: C, 56 map_op: &'f F, 57 } 58 59 impl<'f, C, F> FlatMapIterConsumer<'f, C, F> { new(base: C, map_op: &'f F) -> Self60 fn new(base: C, map_op: &'f F) -> Self { 61 FlatMapIterConsumer { base, map_op } 62 } 63 } 64 65 impl<'f, T, U, C, F> Consumer<T> for FlatMapIterConsumer<'f, C, F> 66 where 67 C: UnindexedConsumer<U::Item>, 68 F: Fn(T) -> U + Sync, 69 U: IntoIterator, 70 { 71 type Folder = FlatMapIterFolder<'f, C::Folder, F>; 72 type Reducer = C::Reducer; 73 type Result = C::Result; 74 split_at(self, index: usize) -> (Self, Self, C::Reducer)75 fn split_at(self, index: usize) -> (Self, Self, C::Reducer) { 76 let (left, right, reducer) = self.base.split_at(index); 77 ( 78 FlatMapIterConsumer::new(left, self.map_op), 79 FlatMapIterConsumer::new(right, self.map_op), 80 reducer, 81 ) 82 } 83 into_folder(self) -> Self::Folder84 fn into_folder(self) -> Self::Folder { 85 FlatMapIterFolder { 86 base: self.base.into_folder(), 87 map_op: self.map_op, 88 } 89 } 90 full(&self) -> bool91 fn full(&self) -> bool { 92 self.base.full() 93 } 94 } 95 96 impl<'f, T, U, C, F> UnindexedConsumer<T> for FlatMapIterConsumer<'f, C, F> 97 where 98 C: UnindexedConsumer<U::Item>, 99 F: Fn(T) -> U + Sync, 100 U: IntoIterator, 101 { split_off_left(&self) -> Self102 fn split_off_left(&self) -> Self { 103 FlatMapIterConsumer::new(self.base.split_off_left(), self.map_op) 104 } 105 to_reducer(&self) -> Self::Reducer106 fn to_reducer(&self) -> Self::Reducer { 107 self.base.to_reducer() 108 } 109 } 110 111 struct FlatMapIterFolder<'f, C, F> { 112 base: C, 113 map_op: &'f F, 114 } 115 116 impl<'f, T, U, C, F> Folder<T> for FlatMapIterFolder<'f, C, F> 117 where 118 C: Folder<U::Item>, 119 F: Fn(T) -> U, 120 U: IntoIterator, 121 { 122 type Result = C::Result; 123 consume(self, item: T) -> Self124 fn consume(self, item: T) -> Self { 125 let map_op = self.map_op; 126 let base = self.base.consume_iter(map_op(item)); 127 FlatMapIterFolder { base, map_op } 128 } 129 consume_iter<I>(self, iter: I) -> Self where I: IntoIterator<Item = T>,130 fn consume_iter<I>(self, iter: I) -> Self 131 where 132 I: IntoIterator<Item = T>, 133 { 134 let map_op = self.map_op; 135 let iter = iter.into_iter().flat_map(map_op); 136 let base = self.base.consume_iter(iter); 137 FlatMapIterFolder { base, map_op } 138 } 139 complete(self) -> Self::Result140 fn complete(self) -> Self::Result { 141 self.base.complete() 142 } 143 full(&self) -> bool144 fn full(&self) -> bool { 145 self.base.full() 146 } 147 } 148