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Auto merge of #81937 - ssomers:btree_drainy_refactor_9b, r=Mark-Simul…
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…acrum

BTree: move more shared iterator code into navigate.rs

The functions in navigate.rs only exist to support iterators, and these look easier on my eyes if there is a shared `struct` with the recurring pair of handles.

r? `@Mark-Simulacrum`
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@bors
bors committed Feb 23, 2021
2 parents 11f838d + 342aa69 commit b02a619
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Showing 2 changed files with 67 additions and 98 deletions.
91 changes: 35 additions & 56 deletions library/alloc/src/collections/btree/map.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@ use core::ops::{Index, RangeBounds};
use core::ptr;

use super::borrow::DormantMutRef;
use super::navigate::LeafRange;
use super::node::{self, marker, ForceResult::*, Handle, NodeRef, Root};
use super::search::SearchResult::*;

Expand Down Expand Up @@ -307,20 +308,15 @@ pub struct IterMut<'a, K: 'a, V: 'a> {
/// [`into_iter`]: IntoIterator::into_iter
#[stable(feature = "rust1", since = "1.0.0")]
pub struct IntoIter<K, V> {
front: Option<Handle<NodeRef<marker::Dying, K, V, marker::Leaf>, marker::Edge>>,
back: Option<Handle<NodeRef<marker::Dying, K, V, marker::Leaf>, marker::Edge>>,
range: LeafRange<marker::Dying, K, V>,
length: usize,
}

impl<K, V> IntoIter<K, V> {
/// Returns an iterator of references over the remaining items.
#[inline]
pub(super) fn iter(&self) -> Iter<'_, K, V> {
let range = Range {
front: self.front.as_ref().map(|f| f.reborrow()),
back: self.back.as_ref().map(|b| b.reborrow()),
};

let range = Range { inner: self.range.reborrow() };
Iter { range: range, length: self.length }
}
}
Expand Down Expand Up @@ -438,8 +434,7 @@ impl<K, V: fmt::Debug> fmt::Debug for IntoValues<K, V> {
/// [`range`]: BTreeMap::range
#[stable(feature = "btree_range", since = "1.17.0")]
pub struct Range<'a, K: 'a, V: 'a> {
front: Option<Handle<NodeRef<marker::Immut<'a>, K, V, marker::Leaf>, marker::Edge>>,
back: Option<Handle<NodeRef<marker::Immut<'a>, K, V, marker::Leaf>, marker::Edge>>,
inner: LeafRange<marker::Immut<'a>, K, V>,
}

#[stable(feature = "collection_debug", since = "1.17.0")]
Expand All @@ -457,8 +452,7 @@ impl<K: fmt::Debug, V: fmt::Debug> fmt::Debug for Range<'_, K, V> {
/// [`range_mut`]: BTreeMap::range_mut
#[stable(feature = "btree_range", since = "1.17.0")]
pub struct RangeMut<'a, K: 'a, V: 'a> {
front: Option<Handle<NodeRef<marker::ValMut<'a>, K, V, marker::Leaf>, marker::Edge>>,
back: Option<Handle<NodeRef<marker::ValMut<'a>, K, V, marker::Leaf>, marker::Edge>>,
inner: LeafRange<marker::ValMut<'a>, K, V>,

// Be invariant in `K` and `V`
_marker: PhantomData<&'a mut (K, V)>,
Expand All @@ -467,10 +461,7 @@ pub struct RangeMut<'a, K: 'a, V: 'a> {
#[stable(feature = "collection_debug", since = "1.17.0")]
impl<K: fmt::Debug, V: fmt::Debug> fmt::Debug for RangeMut<'_, K, V> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let range = Range {
front: self.front.as_ref().map(|f| f.reborrow()),
back: self.back.as_ref().map(|b| b.reborrow()),
};
let range = Range { inner: self.inner.reborrow() };
f.debug_list().entries(range).finish()
}
}
Expand Down Expand Up @@ -1018,11 +1009,9 @@ impl<K, V> BTreeMap<K, V> {
R: RangeBounds<T>,
{
if let Some(root) = &self.root {
let (f, b) = root.reborrow().range_search(range);

Range { front: Some(f), back: Some(b) }
Range { inner: root.reborrow().range_search(range) }
} else {
Range { front: None, back: None }
Range { inner: LeafRange::none() }
}
}

Expand Down Expand Up @@ -1064,11 +1053,9 @@ impl<K, V> BTreeMap<K, V> {
R: RangeBounds<T>,
{
if let Some(root) = &mut self.root {
let (f, b) = root.borrow_valmut().range_search(range);

RangeMut { front: Some(f), back: Some(b), _marker: PhantomData }
RangeMut { inner: root.borrow_valmut().range_search(range), _marker: PhantomData }
} else {
RangeMut { front: None, back: None, _marker: PhantomData }
RangeMut { inner: LeafRange::none(), _marker: PhantomData }
}
}

Expand Down Expand Up @@ -1407,11 +1394,11 @@ impl<K, V> IntoIterator for BTreeMap<K, V> {
fn into_iter(self) -> IntoIter<K, V> {
let mut me = ManuallyDrop::new(self);
if let Some(root) = me.root.take() {
let (f, b) = root.into_dying().full_range();
let full_range = root.into_dying().full_range();

IntoIter { front: Some(f), back: Some(b), length: me.length }
IntoIter { range: full_range, length: me.length }
} else {
IntoIter { front: None, back: None, length: 0 }
IntoIter { range: LeafRange::none(), length: 0 }
}
}
}
Expand Down Expand Up @@ -1450,7 +1437,7 @@ impl<K, V> Drop for Dropper<K, V> {
#[stable(feature = "btree_drop", since = "1.7.0")]
impl<K, V> Drop for IntoIter<K, V> {
fn drop(&mut self) {
if let Some(front) = self.front.take() {
if let Some(front) = self.range.front.take() {
Dropper { front, remaining_length: self.length };
}
}
Expand All @@ -1465,7 +1452,7 @@ impl<K, V> Iterator for IntoIter<K, V> {
None
} else {
self.length -= 1;
Some(unsafe { self.front.as_mut().unwrap().deallocating_next_unchecked() })
Some(unsafe { self.range.front.as_mut().unwrap().deallocating_next_unchecked() })
}
}

Expand All @@ -1481,7 +1468,7 @@ impl<K, V> DoubleEndedIterator for IntoIter<K, V> {
None
} else {
self.length -= 1;
Some(unsafe { self.back.as_mut().unwrap().deallocating_next_back_unchecked() })
Some(unsafe { self.range.back.as_mut().unwrap().deallocating_next_back_unchecked() })
}
}
}
Expand Down Expand Up @@ -1698,7 +1685,7 @@ impl<'a, K, V> Iterator for Range<'a, K, V> {
type Item = (&'a K, &'a V);

fn next(&mut self) -> Option<(&'a K, &'a V)> {
if self.is_empty() { None } else { Some(unsafe { self.next_unchecked() }) }
if self.inner.is_empty() { None } else { Some(unsafe { self.next_unchecked() }) }
}

fn last(mut self) -> Option<(&'a K, &'a V)> {
Expand Down Expand Up @@ -1749,12 +1736,8 @@ impl<K, V> ExactSizeIterator for ValuesMut<'_, K, V> {
impl<K, V> FusedIterator for ValuesMut<'_, K, V> {}

impl<'a, K, V> Range<'a, K, V> {
fn is_empty(&self) -> bool {
self.front == self.back
}

unsafe fn next_unchecked(&mut self) -> (&'a K, &'a V) {
unsafe { self.front.as_mut().unwrap_unchecked().next_unchecked() }
unsafe { self.inner.front.as_mut().unwrap_unchecked().next_unchecked() }
}
}

Expand Down Expand Up @@ -1837,13 +1820,13 @@ impl<K, V> FusedIterator for IntoValues<K, V> {}
#[stable(feature = "btree_range", since = "1.17.0")]
impl<'a, K, V> DoubleEndedIterator for Range<'a, K, V> {
fn next_back(&mut self) -> Option<(&'a K, &'a V)> {
if self.is_empty() { None } else { Some(unsafe { self.next_back_unchecked() }) }
if self.inner.is_empty() { None } else { Some(unsafe { self.next_back_unchecked() }) }
}
}

impl<'a, K, V> Range<'a, K, V> {
unsafe fn next_back_unchecked(&mut self) -> (&'a K, &'a V) {
unsafe { self.back.as_mut().unwrap_unchecked().next_back_unchecked() }
unsafe { self.inner.back.as_mut().unwrap_unchecked().next_back_unchecked() }
}
}

Expand All @@ -1853,7 +1836,7 @@ impl<K, V> FusedIterator for Range<'_, K, V> {}
#[stable(feature = "btree_range", since = "1.17.0")]
impl<K, V> Clone for Range<'_, K, V> {
fn clone(&self) -> Self {
Range { front: self.front, back: self.back }
Range { inner: LeafRange { front: self.inner.front, back: self.inner.back } }
}
}

Expand All @@ -1862,7 +1845,7 @@ impl<'a, K, V> Iterator for RangeMut<'a, K, V> {
type Item = (&'a K, &'a mut V);

fn next(&mut self) -> Option<(&'a K, &'a mut V)> {
if self.is_empty() { None } else { Some(unsafe { self.next_unchecked() }) }
if self.inner.is_empty() { None } else { Some(unsafe { self.next_unchecked() }) }
}

fn last(mut self) -> Option<(&'a K, &'a mut V)> {
Expand All @@ -1879,28 +1862,21 @@ impl<'a, K, V> Iterator for RangeMut<'a, K, V> {
}

impl<'a, K, V> RangeMut<'a, K, V> {
fn is_empty(&self) -> bool {
self.front == self.back
}

unsafe fn next_unchecked(&mut self) -> (&'a K, &'a mut V) {
unsafe { self.front.as_mut().unwrap_unchecked().next_unchecked() }
unsafe { self.inner.front.as_mut().unwrap_unchecked().next_unchecked() }
}

/// Returns an iterator of references over the remaining items.
#[inline]
pub(super) fn iter(&self) -> Range<'_, K, V> {
Range {
front: self.front.as_ref().map(|f| f.reborrow()),
back: self.back.as_ref().map(|b| b.reborrow()),
}
Range { inner: self.inner.reborrow() }
}
}

#[stable(feature = "btree_range", since = "1.17.0")]
impl<'a, K, V> DoubleEndedIterator for RangeMut<'a, K, V> {
fn next_back(&mut self) -> Option<(&'a K, &'a mut V)> {
if self.is_empty() { None } else { Some(unsafe { self.next_back_unchecked() }) }
if self.inner.is_empty() { None } else { Some(unsafe { self.next_back_unchecked() }) }
}
}

Expand All @@ -1909,7 +1885,7 @@ impl<K, V> FusedIterator for RangeMut<'_, K, V> {}

impl<'a, K, V> RangeMut<'a, K, V> {
unsafe fn next_back_unchecked(&mut self) -> (&'a K, &'a mut V) {
unsafe { self.back.as_mut().unwrap_unchecked().next_back_unchecked() }
unsafe { self.inner.back.as_mut().unwrap_unchecked().next_back_unchecked() }
}
}

Expand Down Expand Up @@ -2043,11 +2019,11 @@ impl<K, V> BTreeMap<K, V> {
#[stable(feature = "rust1", since = "1.0.0")]
pub fn iter(&self) -> Iter<'_, K, V> {
if let Some(root) = &self.root {
let (f, b) = root.reborrow().full_range();
let full_range = root.reborrow().full_range();

Iter { range: Range { front: Some(f), back: Some(b) }, length: self.length }
Iter { range: Range { inner: full_range }, length: self.length }
} else {
Iter { range: Range { front: None, back: None }, length: 0 }
Iter { range: Range { inner: LeafRange::none() }, length: 0 }
}
}

Expand Down Expand Up @@ -2075,14 +2051,17 @@ impl<K, V> BTreeMap<K, V> {
#[stable(feature = "rust1", since = "1.0.0")]
pub fn iter_mut(&mut self) -> IterMut<'_, K, V> {
if let Some(root) = &mut self.root {
let (f, b) = root.borrow_valmut().full_range();
let full_range = root.borrow_valmut().full_range();

IterMut {
range: RangeMut { front: Some(f), back: Some(b), _marker: PhantomData },
range: RangeMut { inner: full_range, _marker: PhantomData },
length: self.length,
}
} else {
IterMut { range: RangeMut { front: None, back: None, _marker: PhantomData }, length: 0 }
IterMut {
range: RangeMut { inner: LeafRange::none(), _marker: PhantomData },
length: 0,
}
}
}

Expand Down
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