1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142

use super::plumbing::*;
use super::*;

use std::fmt::{self, Debug};

/// `FilterMap` creates an iterator that uses `filter_op` to both filter and map elements.
/// This struct is created by the [`filter_map()`] method on [`ParallelIterator`].
///
/// [`filter_map()`]: trait.ParallelIterator.html#method.filter_map
/// [`ParallelIterator`]: trait.ParallelIterator.html
#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
#[derive(Clone)]
pub struct FilterMap<I: ParallelIterator, P> {
    base: I,
    filter_op: P,
}

impl<I: ParallelIterator + Debug, P> Debug for FilterMap<I, P> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("FilterMap")
            .field("base", &self.base)
            .finish()
    }
}

impl<I: ParallelIterator, P> FilterMap<I, P> {
    /// Creates a new `FilterMap` iterator.
    pub(super) fn new(base: I, filter_op: P) -> Self {
        FilterMap { base, filter_op }
    }
}

impl<I, P, R> ParallelIterator for FilterMap<I, P>
where
    I: ParallelIterator,
    P: Fn(I::Item) -> Option<R> + Sync + Send,
    R: Send,
{
    type Item = R;

    fn drive_unindexed<C>(self, consumer: C) -> C::Result
    where
        C: UnindexedConsumer<Self::Item>,
    {
        let consumer = FilterMapConsumer::new(consumer, &self.filter_op);
        self.base.drive_unindexed(consumer)
    }
}

/// ////////////////////////////////////////////////////////////////////////
/// Consumer implementation

struct FilterMapConsumer<'p, C, P> {
    base: C,
    filter_op: &'p P,
}

impl<'p, C, P: 'p> FilterMapConsumer<'p, C, P> {
    fn new(base: C, filter_op: &'p P) -> Self {
        FilterMapConsumer { base, filter_op }
    }
}

impl<'p, T, U, C, P> Consumer<T> for FilterMapConsumer<'p, C, P>
where
    C: Consumer<U>,
    P: Fn(T) -> Option<U> + Sync + 'p,
{
    type Folder = FilterMapFolder<'p, C::Folder, P>;
    type Reducer = C::Reducer;
    type Result = C::Result;

    fn split_at(self, index: usize) -> (Self, Self, Self::Reducer) {
        let (left, right, reducer) = self.base.split_at(index);
        (
            FilterMapConsumer::new(left, self.filter_op),
            FilterMapConsumer::new(right, self.filter_op),
            reducer,
        )
    }

    fn into_folder(self) -> Self::Folder {
        let base = self.base.into_folder();
        FilterMapFolder {
            base,
            filter_op: self.filter_op,
        }
    }

    fn full(&self) -> bool {
        self.base.full()
    }
}

impl<'p, T, U, C, P> UnindexedConsumer<T> for FilterMapConsumer<'p, C, P>
where
    C: UnindexedConsumer<U>,
    P: Fn(T) -> Option<U> + Sync + 'p,
{
    fn split_off_left(&self) -> Self {
        FilterMapConsumer::new(self.base.split_off_left(), &self.filter_op)
    }

    fn to_reducer(&self) -> Self::Reducer {
        self.base.to_reducer()
    }
}

struct FilterMapFolder<'p, C, P> {
    base: C,
    filter_op: &'p P,
}

impl<'p, T, U, C, P> Folder<T> for FilterMapFolder<'p, C, P>
where
    C: Folder<U>,
    P: Fn(T) -> Option<U> + Sync + 'p,
{
    type Result = C::Result;

    fn consume(self, item: T) -> Self {
        let filter_op = self.filter_op;
        if let Some(mapped_item) = filter_op(item) {
            let base = self.base.consume(mapped_item);
            FilterMapFolder { base, filter_op }
        } else {
            self
        }
    }

    // This cannot easily specialize `consume_iter` to be better than
    // the default, because that requires checking `self.base.full()`
    // during a call to `self.base.consume_iter()`. (#632)

    fn complete(self) -> C::Result {
        self.base.complete()
    }

    fn full(&self) -> bool {
        self.base.full()
    }
}