repo_description: Rayon: A data parallelism library for Rust
code: use super::plumbing::*;
  use super::*;
  use std::iter;
  
  /// `Zip` is an iterator that zips up `a` and `b` into a single iterator
  /// of pairs. This struct is created by the [`zip()`] method on
  /// [`IndexedParallelIterator`]
  ///
  /// [`zip()`]: IndexedParallelIterator::zip()
  #[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
  #[derive(Debug, Clone)]
  pub struct Zip<A, B> {
      a: A,
      b: B,
  }
  
  impl<A, B> Zip<A, B> {
      /// Creates a new `Zip` iterator.
      pub(super) fn new(a: A, b: B) -> Self {
          Zip { a, b }
      }
  }
  
  impl<A, B> ParallelIterator for Zip<A, B>
  where
      A: IndexedParallelIterator,
      B: IndexedParallelIterator,
  {
      type Item = (A::Item, B::Item);
  
      fn drive_unindexed<C>(self, consumer: C) -> C::Result
      where
          C: UnindexedConsumer<Self::Item>,
      {
          bridge(self, consumer)
      }
  
      fn opt_len(&self) -> Option<usize> {
          Some(self.len())
      }
  }
  
  impl<A, B> IndexedParallelIterator for Zip<A, B>
  where
      A: IndexedParallelIterator,
      B: IndexedParallelIterator,
  {
      fn drive<C>(self, consumer: C) -> C::Result
      where
          C: Consumer<Self::Item>,
      {
          bridge(self, consumer)
      }
  
      fn len(&self) -> usize {
          Ord::min(self.a.len(), self.b.len())
      }
  
      fn with_producer<CB>(self, callback: CB) -> CB::Output
      where
          CB: ProducerCallback<Self::Item>,
      {
          return self.a.with_producer(CallbackA {
              callback,
              b: self.b,
          });
  
          struct CallbackA<CB, B> {
              callback: CB,
              b: B,
          }
  
          impl<CB, ITEM, B> ProducerCallback<ITEM> for CallbackA<CB, B>
          where
              B: IndexedParallelIterator,
              CB: ProducerCallback<(ITEM, B::Item)>,
          {
              type Output = CB::Output;
  
              fn callback<A>(self, a_producer: A) -> Self::Output
              where
                  A: Producer<Item = ITEM>,
              {
                  self.b.with_producer(CallbackB {
                      a_producer,
                      callback: self.callback,
                  })
              }
          }
  
          struct CallbackB<CB, A> {
              a_producer: A,
              callback: CB,
          }
  
          impl<CB, A, ITEM> ProducerCallback<ITEM> for CallbackB<CB, A>
          where
              A: Producer,
              CB: ProducerCallback<(A::Item, ITEM)>,
          {
              type Output = CB::Output;
  
              fn callback<B>(self, b_producer: B) -> Self::Output
              where
                  B: Producer<Item = ITEM>,
              {
                  self.callback.callback(ZipProducer {
                      a: self.a_producer,
                      b: b_producer,
                  })
              }
          }
      }
  }
  
  // ////////////////////////////////////////////////////////////////////////
  
  struct ZipProducer<A: Producer, B: Producer> {
      a: A,
      b: B,
  }
  
  impl<A: Producer, B: Producer> Producer for ZipProducer<A, B> {
      type Item = (A::Item, B::Item);
      type IntoIter = iter::Zip<A::IntoIter, B::IntoIter>;
  
      fn into_iter(self) -> Self::IntoIter {
          self.a.into_iter().zip(self.b.into_iter())
      }
  
      fn min_len(&self) -> usize {
          Ord::max(self.a.min_len(), self.b.min_len())
      }
  
      fn max_len(&self) -> usize {
          Ord::min(self.a.max_len(), self.b.max_len())
      }
  
      fn split_at(self, index: usize) -> (Self, Self) {
          let (a_left, a_right) = self.a.split_at(index);
          let (b_left, b_right) = self.b.split_at(index);
          (
              ZipProducer {
                  a: a_left,
                  b: b_left,
              },
              ZipProducer {
                  a: a_right,
                  b: b_right,
              },
          )
      }
  }
  