rayon/
delegate.rs

1//! Macros for delegating newtype iterators to inner types.
2
3// Note: these place `impl` bounds at the end, as token gobbling is the only way
4// I know how to consume an arbitrary list of constraints, with `$($args:tt)*`.
5
6/// Creates a parallel iterator implementation which simply wraps an inner type
7/// and delegates all methods inward.  The actual struct must already be
8/// declared with an `inner` field.
9///
10/// The implementation of `IntoParallelIterator` should be added separately.
11macro_rules! delegate_iterator {
12    ($iter:ty => $item:ty ,
13     impl $( $args:tt )*
14     ) => {
15        impl $( $args )* ParallelIterator for $iter {
16            type Item = $item;
17
18            fn drive_unindexed<C>(self, consumer: C) -> C::Result
19                where C: UnindexedConsumer<Self::Item>
20            {
21                self.inner.drive_unindexed(consumer)
22            }
23
24            fn opt_len(&self) -> Option<usize> {
25                self.inner.opt_len()
26            }
27        }
28    }
29}
30
31/// Creates an indexed parallel iterator implementation which simply wraps an
32/// inner type and delegates all methods inward.  The actual struct must already
33/// be declared with an `inner` field.
34macro_rules! delegate_indexed_iterator {
35    ($iter:ty => $item:ty ,
36     impl $( $args:tt )*
37     ) => {
38        delegate_iterator!{
39            $iter => $item ,
40            impl $( $args )*
41        }
42
43        impl $( $args )* IndexedParallelIterator for $iter {
44            fn drive<C>(self, consumer: C) -> C::Result
45                where C: Consumer<Self::Item>
46            {
47                self.inner.drive(consumer)
48            }
49
50            fn len(&self) -> usize {
51                self.inner.len()
52            }
53
54            fn with_producer<CB>(self, callback: CB) -> CB::Output
55                where CB: ProducerCallback<Self::Item>
56            {
57                self.inner.with_producer(callback)
58            }
59        }
60    }
61}
62
63#[test]
64fn unindexed_example() {
65    use crate::collections::btree_map::IntoIter;
66    use crate::iter::plumbing::*;
67    use crate::prelude::*;
68
69    use std::collections::BTreeMap;
70
71    struct MyIntoIter<T: Ord + Send, U: Send> {
72        inner: IntoIter<T, U>,
73    }
74
75    delegate_iterator! {
76        MyIntoIter<T, U> => (T, U),
77        impl<T: Ord + Send, U: Send>
78    }
79
80    let map = BTreeMap::from([(1, 'a'), (2, 'b'), (3, 'c')]);
81    let iter = MyIntoIter {
82        inner: map.into_par_iter(),
83    };
84    let vec: Vec<_> = iter.map(|(k, _)| k).collect();
85    assert_eq!(vec, &[1, 2, 3]);
86}
87
88#[test]
89fn indexed_example() {
90    use crate::iter::plumbing::*;
91    use crate::prelude::*;
92    use crate::vec::IntoIter;
93
94    struct MyIntoIter<T: Send> {
95        inner: IntoIter<T>,
96    }
97
98    delegate_indexed_iterator! {
99        MyIntoIter<T> => T,
100        impl<T: Send>
101    }
102
103    let iter = MyIntoIter {
104        inner: vec![1, 2, 3].into_par_iter(),
105    };
106    let mut vec = vec![];
107    iter.collect_into_vec(&mut vec);
108    assert_eq!(vec, &[1, 2, 3]);
109}
rayon/delegate.rs

rayon/
delegate.rs
