Move iterator code into a module

Author: cuviper

src/iterator.rs

@@ -0,0 +1,254 @@
+use super::{for_both, Either, Left, Right};
+use core::iter;
+
+impl<L, R> Either<L, R> {
+    /// Convert the inner value to an iterator.
+    ///
+    /// ```
+    /// use either::*;
+    ///
+    /// let left: Either<_, Vec<u32>> = Left(vec![1, 2, 3, 4, 5]);
+    /// let mut right: Either<Vec<u32>, _> = Right(vec![]);
+    /// right.extend(left.into_iter());
+    /// assert_eq!(right, Right(vec![1, 2, 3, 4, 5]));
+    /// ```
+    #[allow(clippy::should_implement_trait)]
+    pub fn into_iter(self) -> Either<L::IntoIter, R::IntoIter>
+    where
+        L: IntoIterator,
+        R: IntoIterator<Item = L::Item>,
+    {
+        match self {
+            Left(l) => Left(l.into_iter()),
+            Right(r) => Right(r.into_iter()),
+        }
+    }
+
+    /// Borrow the inner value as an iterator.
+    ///
+    /// ```
+    /// use either::*;
+    ///
+    /// let left: Either<_, &[u32]> = Left(vec![2, 3]);
+    /// let mut right: Either<Vec<u32>, _> = Right([4, 5].as_slice());
+    /// let mut all = vec![1];
+    /// all.extend(left.iter());
+    /// all.extend(right.iter());
+    /// assert_eq!(all, vec![1, 2, 3, 4, 5]);
+    /// ```
+    pub fn iter(&self) -> Either<<&L as IntoIterator>::IntoIter, <&R as IntoIterator>::IntoIter>
+    where
+        for<'a> &'a L: IntoIterator,
+        for<'a> &'a R: IntoIterator<Item = <&'a L as IntoIterator>::Item>,
+    {
+        self.as_ref().into_iter()
+    }
+
+    /// Mutably borrow the inner value as an iterator.
+    ///
+    /// ```
+    /// use either::*;
+    ///
+    /// let mut left: Either<_, &mut [u32]> = Left(vec![2, 3]);
+    /// for l in left.iter_mut() {
+    ///     *l *= *l
+    /// }
+    /// assert_eq!(left, Left(vec![4, 9]));
+    ///
+    /// let mut inner = [4, 5];
+    /// let mut right: Either<Vec<u32>, _> = Right(inner.as_mut_slice());
+    /// for r in right.iter_mut() {
+    ///     *r *= *r
+    /// }
+    /// assert_eq!(inner, [16, 25]);
+    /// ```
+    pub fn iter_mut(
+        &mut self,
+    ) -> Either<<&mut L as IntoIterator>::IntoIter, <&mut R as IntoIterator>::IntoIter>
+    where
+        for<'a> &'a mut L: IntoIterator,
+        for<'a> &'a mut R: IntoIterator<Item = <&'a mut L as IntoIterator>::Item>,
+    {
+        self.as_mut().into_iter()
+    }
+
+    /// Factors an `Either` of `Iterator`s to be an `Iterator` of `Either`s
+    /// ```
+    /// use either::*;
+    /// let left: Either<_, Vec<u8>> = Left(&["hello"]);
+    /// assert_eq!(left.factor_iter().next(), Some(Left(&"hello")));
+
+    /// let right: Either<&[&str], _> = Right(vec![0, 1]);
+    /// assert_eq!(right.factor_iter().collect::<Vec<_>>(), vec![Right(0), Right(1)]);
+    ///
+    /// ```
+    // TODO(MSRV): doc(alias) was stabilized in Rust 1.48
+    // #[doc(alias = "transpose")]
+    pub fn factor_iter(
+        self,
+    ) -> Either<
+        core::iter::Map<L::IntoIter, impl Fn(L::Item) -> Either<L::Item, R::Item>>,
+        core::iter::Map<R::IntoIter, impl Fn(R::Item) -> Either<L::Item, R::Item>>,
+    >
+    where
+        L: IntoIterator,
+        R: IntoIterator,
+    {
+        self.map_either(
+            |l| l.into_iter().map(Either::Left),
+            |r| r.into_iter().map(Either::Right),
+        )
+    }
+}
+
+impl<L, R, A> Extend<A> for Either<L, R>
+where
+    L: Extend<A>,
+    R: Extend<A>,
+{
+    fn extend<T>(&mut self, iter: T)
+    where
+        T: IntoIterator<Item = A>,
+    {
+        for_both!(*self, ref mut inner => inner.extend(iter))
+    }
+}
+
+/// `Either<L, R>` is an iterator if both `L` and `R` are iterators.
+impl<L, R> Iterator for Either<L, R>
+where
+    L: Iterator,
+    R: Iterator<Item = L::Item>,
+{
+    type Item = L::Item;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        for_both!(*self, ref mut inner => inner.next())
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        for_both!(*self, ref inner => inner.size_hint())
+    }
+
+    fn fold<Acc, G>(self, init: Acc, f: G) -> Acc
+    where
+        G: FnMut(Acc, Self::Item) -> Acc,
+    {
+        for_both!(self, inner => inner.fold(init, f))
+    }
+
+    fn for_each<F>(self, f: F)
+    where
+        F: FnMut(Self::Item),
+    {
+        for_both!(self, inner => inner.for_each(f))
+    }
+
+    fn count(self) -> usize {
+        for_both!(self, inner => inner.count())
+    }
+
+    fn last(self) -> Option<Self::Item> {
+        for_both!(self, inner => inner.last())
+    }
+
+    fn nth(&mut self, n: usize) -> Option<Self::Item> {
+        for_both!(*self, ref mut inner => inner.nth(n))
+    }
+
+    fn collect<B>(self) -> B
+    where
+        B: iter::FromIterator<Self::Item>,
+    {
+        for_both!(self, inner => inner.collect())
+    }
+
+    fn partition<B, F>(self, f: F) -> (B, B)
+    where
+        B: Default + Extend<Self::Item>,
+        F: FnMut(&Self::Item) -> bool,
+    {
+        for_both!(self, inner => inner.partition(f))
+    }
+
+    fn all<F>(&mut self, f: F) -> bool
+    where
+        F: FnMut(Self::Item) -> bool,
+    {
+        for_both!(*self, ref mut inner => inner.all(f))
+    }
+
+    fn any<F>(&mut self, f: F) -> bool
+    where
+        F: FnMut(Self::Item) -> bool,
+    {
+        for_both!(*self, ref mut inner => inner.any(f))
+    }
+
+    fn find<P>(&mut self, predicate: P) -> Option<Self::Item>
+    where
+        P: FnMut(&Self::Item) -> bool,
+    {
+        for_both!(*self, ref mut inner => inner.find(predicate))
+    }
+
+    fn find_map<B, F>(&mut self, f: F) -> Option<B>
+    where
+        F: FnMut(Self::Item) -> Option<B>,
+    {
+        for_both!(*self, ref mut inner => inner.find_map(f))
+    }
+
+    fn position<P>(&mut self, predicate: P) -> Option<usize>
+    where
+        P: FnMut(Self::Item) -> bool,
+    {
+        for_both!(*self, ref mut inner => inner.position(predicate))
+    }
+}
+
+impl<L, R> DoubleEndedIterator for Either<L, R>
+where
+    L: DoubleEndedIterator,
+    R: DoubleEndedIterator<Item = L::Item>,
+{
+    fn next_back(&mut self) -> Option<Self::Item> {
+        for_both!(*self, ref mut inner => inner.next_back())
+    }
+
+    // TODO(MSRV): This was stabilized in Rust 1.37
+    // fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
+    //     for_both!(*self, ref mut inner => inner.nth_back(n))
+    // }
+
+    fn rfold<Acc, G>(self, init: Acc, f: G) -> Acc
+    where
+        G: FnMut(Acc, Self::Item) -> Acc,
+    {
+        for_both!(self, inner => inner.rfold(init, f))
+    }
+
+    fn rfind<P>(&mut self, predicate: P) -> Option<Self::Item>
+    where
+        P: FnMut(&Self::Item) -> bool,
+    {
+        for_both!(*self, ref mut inner => inner.rfind(predicate))
+    }
+}
+
+impl<L, R> ExactSizeIterator for Either<L, R>
+where
+    L: ExactSizeIterator,
+    R: ExactSizeIterator<Item = L::Item>,
+{
+    fn len(&self) -> usize {
+        for_both!(*self, ref inner => inner.len())
+    }
+}
+
+impl<L, R> iter::FusedIterator for Either<L, R>
+where
+    L: iter::FusedIterator,
+    R: iter::FusedIterator<Item = L::Item>,
+{
+}