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

/// An [`IndexedParallelIterator`] that iterates over two parallel iterators of equal
/// length simultaneously.
///
/// This struct is created by the [`zip_eq`] method on [`IndexedParallelIterator`],
/// see its documentation for more information.
///
/// [`zip_eq`]: trait.IndexedParallelIterator.html#method.zip_eq
/// [`IndexedParallelIterator`]: trait.IndexedParallelIterator.html
#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
#[derive(Debug, Clone)]
pub struct ZipEq<A: IndexedParallelIterator, B: IndexedParallelIterator> {
    zip: Zip<A, B>,
}

impl<A, B> ZipEq<A, B>
where
    A: IndexedParallelIterator,
    B: IndexedParallelIterator,
{
    /// Creates a new `ZipEq` iterator.
    pub(super) fn new(a: A, b: B) -> Self {
        ZipEq {
            zip: super::Zip::new(a, b),
        }
    }
}

impl<A, B> ParallelIterator for ZipEq<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.zip, consumer)
    }

    fn opt_len(&self) -> Option<usize> {
        Some(self.zip.len())
    }
}

impl<A, B> IndexedParallelIterator for ZipEq<A, B>
where
    A: IndexedParallelIterator,
    B: IndexedParallelIterator,
{
    fn drive<C>(self, consumer: C) -> C::Result
    where
        C: Consumer<Self::Item>,
    {
        bridge(self.zip, consumer)
    }

    fn len(&self) -> usize {
        self.zip.len()
    }

    fn with_producer<CB>(self, callback: CB) -> CB::Output
    where
        CB: ProducerCallback<Self::Item>,
    {
        self.zip.with_producer(callback)
    }
}