Move Zip and ZipImpl to own module

Author: Clar Fon

src/libcore/iter/adapters/mod.rs

@@ -7,6 +7,11 @@ use intrinsics;
 use super::{Iterator, DoubleEndedIterator, ExactSizeIterator, FusedIterator, TrustedLen};
 use super::LoopState;
 
+mod zip;
+
+pub use self::zip::Zip;
+pub(super) use self::zip::ZipImpl;
+
 /// A double-ended iterator with the direction inverted.
 ///
 /// This `struct` is created by the [`rev`] method on [`Iterator`]. See its
@@ -703,264 +708,6 @@ unsafe impl<A, B> TrustedLen for Chain<A, B>
     where A: TrustedLen, B: TrustedLen<Item=A::Item>,
 {}
 
-/// An iterator that iterates two other iterators simultaneously.
-///
-/// This `struct` is created by the [`zip`] method on [`Iterator`]. See its
-/// documentation for more.
-///
-/// [`zip`]: trait.Iterator.html#method.zip
-/// [`Iterator`]: trait.Iterator.html
-#[derive(Clone, Debug)]
-#[must_use = "iterators are lazy and do nothing unless consumed"]
-#[stable(feature = "rust1", since = "1.0.0")]
-pub struct Zip<A, B> {
-    a: A,
-    b: B,
-    // index and len are only used by the specialized version of zip
-    index: usize,
-    len: usize,
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<A, B> Iterator for Zip<A, B> where A: Iterator, B: Iterator
-{
-    type Item = (A::Item, B::Item);
-
-    #[inline]
-    fn next(&mut self) -> Option<Self::Item> {
-        ZipImpl::next(self)
-    }
-
-    #[inline]
-    fn size_hint(&self) -> (usize, Option<usize>) {
-        ZipImpl::size_hint(self)
-    }
-
-    #[inline]
-    fn nth(&mut self, n: usize) -> Option<Self::Item> {
-        ZipImpl::nth(self, n)
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<A, B> DoubleEndedIterator for Zip<A, B> where
-    A: DoubleEndedIterator + ExactSizeIterator,
-    B: DoubleEndedIterator + ExactSizeIterator,
-{
-    #[inline]
-    fn next_back(&mut self) -> Option<(A::Item, B::Item)> {
-        ZipImpl::next_back(self)
-    }
-}
-
-// Zip specialization trait
-#[doc(hidden)]
-pub(super) trait ZipImpl<A, B> {
-    type Item;
-    fn new(a: A, b: B) -> Self;
-    fn next(&mut self) -> Option<Self::Item>;
-    fn size_hint(&self) -> (usize, Option<usize>);
-    fn nth(&mut self, n: usize) -> Option<Self::Item>;
-    fn super_nth(&mut self, mut n: usize) -> Option<Self::Item> {
-        while let Some(x) = self.next() {
-            if n == 0 { return Some(x) }
-            n -= 1;
-        }
-        None
-    }
-    fn next_back(&mut self) -> Option<Self::Item>
-        where A: DoubleEndedIterator + ExactSizeIterator,
-              B: DoubleEndedIterator + ExactSizeIterator;
-}
-
-// General Zip impl
-#[doc(hidden)]
-impl<A, B> ZipImpl<A, B> for Zip<A, B>
-    where A: Iterator, B: Iterator
-{
-    type Item = (A::Item, B::Item);
-    default fn new(a: A, b: B) -> Self {
-        Zip {
-            a,
-            b,
-            index: 0, // unused
-            len: 0, // unused
-        }
-    }
-
-    #[inline]
-    default fn next(&mut self) -> Option<(A::Item, B::Item)> {
-        self.a.next().and_then(|x| {
-            self.b.next().and_then(|y| {
-                Some((x, y))
-            })
-        })
-    }
-
-    #[inline]
-    default fn nth(&mut self, n: usize) -> Option<Self::Item> {
-        self.super_nth(n)
-    }
-
-    #[inline]
-    default fn next_back(&mut self) -> Option<(A::Item, B::Item)>
-        where A: DoubleEndedIterator + ExactSizeIterator,
-              B: DoubleEndedIterator + ExactSizeIterator
-    {
-        let a_sz = self.a.len();
-        let b_sz = self.b.len();
-        if a_sz != b_sz {
-            // Adjust a, b to equal length
-            if a_sz > b_sz {
-                for _ in 0..a_sz - b_sz { self.a.next_back(); }
-            } else {
-                for _ in 0..b_sz - a_sz { self.b.next_back(); }
-            }
-        }
-        match (self.a.next_back(), self.b.next_back()) {
-            (Some(x), Some(y)) => Some((x, y)),
-            (None, None) => None,
-            _ => unreachable!(),
-        }
-    }
-
-    #[inline]
-    default fn size_hint(&self) -> (usize, Option<usize>) {
-        let (a_lower, a_upper) = self.a.size_hint();
-        let (b_lower, b_upper) = self.b.size_hint();
-
-        let lower = cmp::min(a_lower, b_lower);
-
-        let upper = match (a_upper, b_upper) {
-            (Some(x), Some(y)) => Some(cmp::min(x,y)),
-            (Some(x), None) => Some(x),
-            (None, Some(y)) => Some(y),
-            (None, None) => None
-        };
-
-        (lower, upper)
-    }
-}
-
-#[doc(hidden)]
-impl<A, B> ZipImpl<A, B> for Zip<A, B>
-    where A: TrustedRandomAccess, B: TrustedRandomAccess
-{
-    fn new(a: A, b: B) -> Self {
-        let len = cmp::min(a.len(), b.len());
-        Zip {
-            a,
-            b,
-            index: 0,
-            len,
-        }
-    }
-
-    #[inline]
-    fn next(&mut self) -> Option<(A::Item, B::Item)> {
-        if self.index < self.len {
-            let i = self.index;
-            self.index += 1;
-            unsafe {
-                Some((self.a.get_unchecked(i), self.b.get_unchecked(i)))
-            }
-        } else if A::may_have_side_effect() && self.index < self.a.len() {
-            // match the base implementation's potential side effects
-            unsafe {
-                self.a.get_unchecked(self.index);
-            }
-            self.index += 1;
-            None
-        } else {
-            None
-        }
-    }
-
-    #[inline]
-    fn size_hint(&self) -> (usize, Option<usize>) {
-        let len = self.len - self.index;
-        (len, Some(len))
-    }
-
-    #[inline]
-    fn nth(&mut self, n: usize) -> Option<Self::Item> {
-        let delta = cmp::min(n, self.len - self.index);
-        let end = self.index + delta;
-        while self.index < end {
-            let i = self.index;
-            self.index += 1;
-            if A::may_have_side_effect() {
-                unsafe { self.a.get_unchecked(i); }
-            }
-            if B::may_have_side_effect() {
-                unsafe { self.b.get_unchecked(i); }
-            }
-        }
-
-        self.super_nth(n - delta)
-    }
-
-    #[inline]
-    fn next_back(&mut self) -> Option<(A::Item, B::Item)>
-        where A: DoubleEndedIterator + ExactSizeIterator,
-              B: DoubleEndedIterator + ExactSizeIterator
-    {
-        // Adjust a, b to equal length
-        if A::may_have_side_effect() {
-            let sz = self.a.len();
-            if sz > self.len {
-                for _ in 0..sz - cmp::max(self.len, self.index) {
-                    self.a.next_back();
-                }
-            }
-        }
-        if B::may_have_side_effect() {
-            let sz = self.b.len();
-            if sz > self.len {
-                for _ in 0..sz - self.len {
-                    self.b.next_back();
-                }
-            }
-        }
-        if self.index < self.len {
-            self.len -= 1;
-            let i = self.len;
-            unsafe {
-                Some((self.a.get_unchecked(i), self.b.get_unchecked(i)))
-            }
-        } else {
-            None
-        }
-    }
-}
-
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<A, B> ExactSizeIterator for Zip<A, B>
-    where A: ExactSizeIterator, B: ExactSizeIterator {}
-
-#[doc(hidden)]
-unsafe impl<A, B> TrustedRandomAccess for Zip<A, B>
-    where A: TrustedRandomAccess,
-          B: TrustedRandomAccess,
-{
-    unsafe fn get_unchecked(&mut self, i: usize) -> (A::Item, B::Item) {
-        (self.a.get_unchecked(i), self.b.get_unchecked(i))
-    }
-
-    fn may_have_side_effect() -> bool {
-        A::may_have_side_effect() || B::may_have_side_effect()
-    }
-}
-
-#[stable(feature = "fused", since = "1.26.0")]
-impl<A, B> FusedIterator for Zip<A, B>
-    where A: FusedIterator, B: FusedIterator, {}
-
-#[unstable(feature = "trusted_len", issue = "37572")]
-unsafe impl<A, B> TrustedLen for Zip<A, B>
-    where A: TrustedLen, B: TrustedLen,
-{}
-
 /// An iterator that maps the values of `iter` with `f`.
 ///
 /// This `struct` is created by the [`map`] method on [`Iterator`]. See its