src/vendor/rayon/src/iter/product.rs

   1 use super::ParallelIterator;
   2 use super::plumbing::*;
   3
   4 use std::iter::{self, Product};
   5 use std::marker::PhantomData;
   6
   7
   8 pub fn product<PI, P>(pi: PI) -> P
   9     where PI: ParallelIterator,
  10           P: Send + Product<PI::Item> + Product
  11 {
  12     pi.drive_unindexed(ProductConsumer::new())
  13 }
  14
  15 fn mul<T: Product>(left: T, right: T) -> T {
  16     iter::once(left).chain(iter::once(right)).product()
  17 }
  18
  19
  20 struct ProductConsumer<P: Send> {
  21     _marker: PhantomData<*const P>,
  22 }
  23
  24 unsafe impl<P: Send> Send for ProductConsumer<P> {}
  25
  26 impl<P: Send> ProductConsumer<P> {
  27     fn new() -> ProductConsumer<P> {
  28         ProductConsumer { _marker: PhantomData }
  29     }
  30 }
  31
  32 impl<P, T> Consumer<T> for ProductConsumer<P>
  33     where P: Send + Product<T> + Product
  34 {
  35     type Folder = ProductFolder<P>;
  36     type Reducer = Self;
  37     type Result = P;
  38
  39     fn split_at(self, _index: usize) -> (Self, Self, Self) {
  40         (ProductConsumer::new(), ProductConsumer::new(), ProductConsumer::new())
  41     }
  42
  43     fn into_folder(self) -> Self::Folder {
  44         ProductFolder { product: iter::empty::<T>().product() }
  45     }
  46
  47     fn full(&self) -> bool {
  48         false
  49     }
  50 }
  51
  52 impl<P, T> UnindexedConsumer<T> for ProductConsumer<P>
  53     where P: Send + Product<T> + Product
  54 {
  55     fn split_off_left(&self) -> Self {
  56         ProductConsumer::new()
  57     }
  58
  59     fn to_reducer(&self) -> Self::Reducer {
  60         ProductConsumer::new()
  61     }
  62 }
  63
  64 impl<P> Reducer<P> for ProductConsumer<P>
  65     where P: Send + Product
  66 {
  67     fn reduce(self, left: P, right: P) -> P {
  68         mul(left, right)
  69     }
  70 }
  71
  72
  73 struct ProductFolder<P> {
  74     product: P,
  75 }
  76
  77 impl<P, T> Folder<T> for ProductFolder<P>
  78     where P: Product<T> + Product
  79 {
  80     type Result = P;
  81
  82     fn consume(self, item: T) -> Self {
  83         ProductFolder { product: mul(self.product, iter::once(item).product()) }
  84     }
  85
  86     fn consume_iter<I>(self, iter: I) -> Self
  87         where I: IntoIterator<Item = T>
  88     {
  89         ProductFolder { product: mul(self.product, iter.into_iter().product()) }
  90     }
  91
  92     fn complete(self) -> P {
  93         self.product
  94     }
  95
  96     fn full(&self) -> bool {
  97         false
  98     }
  99 }