1 use super::plumbing::*;
2 use super::*;
3 use std::cmp;
4 use std::iter;
5 
6 /// `Zip` is an iterator that zips up `a` and `b` into a single iterator
7 /// of pairs. This struct is created by the [`zip()`] method on
8 /// [`IndexedParallelIterator`]
9 ///
10 /// [`zip()`]: trait.IndexedParallelIterator.html#method.zip
11 /// [`IndexedParallelIterator`]: trait.IndexedParallelIterator.html
12 #[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
13 #[derive(Debug, Clone)]
14 pub struct Zip<A: IndexedParallelIterator, B: IndexedParallelIterator> {
15     a: A,
16     b: B,
17 }
18 
19 impl<A, B> Zip<A, B>
20 where
21     A: IndexedParallelIterator,
22     B: IndexedParallelIterator,
23 {
24     /// Creates a new `Zip` iterator.
new(a: A, b: B) -> Self25     pub(super) fn new(a: A, b: B) -> Self {
26         Zip { a, b }
27     }
28 }
29 
30 impl<A, B> ParallelIterator for Zip<A, B>
31 where
32     A: IndexedParallelIterator,
33     B: IndexedParallelIterator,
34 {
35     type Item = (A::Item, B::Item);
36 
drive_unindexed<C>(self, consumer: C) -> C::Result where C: UnindexedConsumer<Self::Item>,37     fn drive_unindexed<C>(self, consumer: C) -> C::Result
38     where
39         C: UnindexedConsumer<Self::Item>,
40     {
41         bridge(self, consumer)
42     }
43 
opt_len(&self) -> Option<usize>44     fn opt_len(&self) -> Option<usize> {
45         Some(self.len())
46     }
47 }
48 
49 impl<A, B> IndexedParallelIterator for Zip<A, B>
50 where
51     A: IndexedParallelIterator,
52     B: IndexedParallelIterator,
53 {
drive<C>(self, consumer: C) -> C::Result where C: Consumer<Self::Item>,54     fn drive<C>(self, consumer: C) -> C::Result
55     where
56         C: Consumer<Self::Item>,
57     {
58         bridge(self, consumer)
59     }
60 
len(&self) -> usize61     fn len(&self) -> usize {
62         cmp::min(self.a.len(), self.b.len())
63     }
64 
with_producer<CB>(self, callback: CB) -> CB::Output where CB: ProducerCallback<Self::Item>,65     fn with_producer<CB>(self, callback: CB) -> CB::Output
66     where
67         CB: ProducerCallback<Self::Item>,
68     {
69         return self.a.with_producer(CallbackA {
70             callback,
71             b: self.b,
72         });
73 
74         struct CallbackA<CB, B> {
75             callback: CB,
76             b: B,
77         }
78 
79         impl<CB, ITEM, B> ProducerCallback<ITEM> for CallbackA<CB, B>
80         where
81             B: IndexedParallelIterator,
82             CB: ProducerCallback<(ITEM, B::Item)>,
83         {
84             type Output = CB::Output;
85 
86             fn callback<A>(self, a_producer: A) -> Self::Output
87             where
88                 A: Producer<Item = ITEM>,
89             {
90                 self.b.with_producer(CallbackB {
91                     a_producer,
92                     callback: self.callback,
93                 })
94             }
95         }
96 
97         struct CallbackB<CB, A> {
98             a_producer: A,
99             callback: CB,
100         }
101 
102         impl<CB, A, ITEM> ProducerCallback<ITEM> for CallbackB<CB, A>
103         where
104             A: Producer,
105             CB: ProducerCallback<(A::Item, ITEM)>,
106         {
107             type Output = CB::Output;
108 
109             fn callback<B>(self, b_producer: B) -> Self::Output
110             where
111                 B: Producer<Item = ITEM>,
112             {
113                 self.callback.callback(ZipProducer {
114                     a: self.a_producer,
115                     b: b_producer,
116                 })
117             }
118         }
119     }
120 }
121 
122 /// ////////////////////////////////////////////////////////////////////////
123 
124 struct ZipProducer<A: Producer, B: Producer> {
125     a: A,
126     b: B,
127 }
128 
129 impl<A: Producer, B: Producer> Producer for ZipProducer<A, B> {
130     type Item = (A::Item, B::Item);
131     type IntoIter = iter::Zip<A::IntoIter, B::IntoIter>;
132 
into_iter(self) -> Self::IntoIter133     fn into_iter(self) -> Self::IntoIter {
134         self.a.into_iter().zip(self.b.into_iter())
135     }
136 
min_len(&self) -> usize137     fn min_len(&self) -> usize {
138         cmp::max(self.a.min_len(), self.b.min_len())
139     }
140 
max_len(&self) -> usize141     fn max_len(&self) -> usize {
142         cmp::min(self.a.max_len(), self.b.max_len())
143     }
144 
split_at(self, index: usize) -> (Self, Self)145     fn split_at(self, index: usize) -> (Self, Self) {
146         let (a_left, a_right) = self.a.split_at(index);
147         let (b_left, b_right) = self.b.split_at(index);
148         (
149             ZipProducer {
150                 a: a_left,
151                 b: b_left,
152             },
153             ZipProducer {
154                 a: a_right,
155                 b: b_right,
156             },
157         )
158     }
159 }
160