1use super::plumbing::*;
2use super::*;
3
4use std::fmt::{self, Debug};
5
6/// `FilterMap` creates an iterator that uses `filter_op` to both filter and map elements.
7/// This struct is created by the [`filter_map()`] method on [`ParallelIterator`].
8///
9/// [`filter_map()`]: trait.ParallelIterator.html#method.filter_map
10/// [`ParallelIterator`]: trait.ParallelIterator.html
11#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
12#[derive(Clone)]
13pub struct FilterMap<I: ParallelIterator, P> {
14 base: I,
15 filter_op: P,
16}
17
18impl<I: ParallelIterator + Debug, P> Debug for FilterMap<I, P> {
19 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
20 f.debug_struct("FilterMap")
21 .field("base", &self.base)
22 .finish()
23 }
24}
25
26impl<I: ParallelIterator, P> FilterMap<I, P> {
27 /// Creates a new `FilterMap` iterator.
28 pub(super) fn new(base: I, filter_op: P) -> Self {
29 FilterMap { base, filter_op }
30 }
31}
32
33impl<I, P, R> ParallelIterator for FilterMap<I, P>
34where
35 I: ParallelIterator,
36 P: Fn(I::Item) -> Option<R> + Sync + Send,
37 R: Send,
38{
39 type Item = R;
40
41 fn drive_unindexed<C>(self, consumer: C) -> C::Result
42 where
43 C: UnindexedConsumer<Self::Item>,
44 {
45 let consumer = FilterMapConsumer::new(consumer, &self.filter_op);
46 self.base.drive_unindexed(consumer)
47 }
48}
49
50/// ////////////////////////////////////////////////////////////////////////
51/// Consumer implementation
52
53struct FilterMapConsumer<'p, C, P> {
54 base: C,
55 filter_op: &'p P,
56}
57
58impl<'p, C, P: 'p> FilterMapConsumer<'p, C, P> {
59 fn new(base: C, filter_op: &'p P) -> Self {
60 FilterMapConsumer { base, filter_op }
61 }
62}
63
64impl<'p, T, U, C, P> Consumer<T> for FilterMapConsumer<'p, C, P>
65where
66 C: Consumer<U>,
67 P: Fn(T) -> Option<U> + Sync + 'p,
68{
69 type Folder = FilterMapFolder<'p, C::Folder, P>;
70 type Reducer = C::Reducer;
71 type Result = C::Result;
72
73 fn split_at(self, index: usize) -> (Self, Self, Self::Reducer) {
74 let (left, right, reducer) = self.base.split_at(index);
75 (
76 FilterMapConsumer::new(left, self.filter_op),
77 FilterMapConsumer::new(right, self.filter_op),
78 reducer,
79 )
80 }
81
82 fn into_folder(self) -> Self::Folder {
83 let base = self.base.into_folder();
84 FilterMapFolder {
85 base,
86 filter_op: self.filter_op,
87 }
88 }
89
90 fn full(&self) -> bool {
91 self.base.full()
92 }
93}
94
95impl<'p, T, U, C, P> UnindexedConsumer<T> for FilterMapConsumer<'p, C, P>
96where
97 C: UnindexedConsumer<U>,
98 P: Fn(T) -> Option<U> + Sync + 'p,
99{
100 fn split_off_left(&self) -> Self {
101 FilterMapConsumer::new(self.base.split_off_left(), self.filter_op)
102 }
103
104 fn to_reducer(&self) -> Self::Reducer {
105 self.base.to_reducer()
106 }
107}
108
109struct FilterMapFolder<'p, C, P> {
110 base: C,
111 filter_op: &'p P,
112}
113
114impl<'p, T, U, C, P> Folder<T> for FilterMapFolder<'p, C, P>
115where
116 C: Folder<U>,
117 P: Fn(T) -> Option<U> + Sync + 'p,
118{
119 type Result = C::Result;
120
121 fn consume(self, item: T) -> Self {
122 let filter_op = self.filter_op;
123 if let Some(mapped_item) = filter_op(item) {
124 let base = self.base.consume(mapped_item);
125 FilterMapFolder { base, filter_op }
126 } else {
127 self
128 }
129 }
130
131 // This cannot easily specialize `consume_iter` to be better than
132 // the default, because that requires checking `self.base.full()`
133 // during a call to `self.base.consume_iter()`. (#632)
134
135 fn complete(self) -> C::Result {
136 self.base.complete()
137 }
138
139 fn full(&self) -> bool {
140 self.base.full()
141 }
142}
143