From 293cdf7ac5d14811debdec3408afde104935caef Mon Sep 17 00:00:00 2001
From: Charles Gleason <charles_gleason@alumni.brown.edu>
Date: Thu, 21 Nov 2019 22:09:10 -0500
Subject: [PATCH 1/7] Make RangeMut::next_unchecked() output a mutable key
reference
---
src/liballoc/collections/btree/map.rs | 22 +++++++++++++++-------
1 file changed, 15 insertions(+), 7 deletions(-)
diff --git a/src/liballoc/collections/btree/map.rs b/src/liballoc/collections/btree/map.rs
index 7d0a862d79e48..e25a5e0773ec6 100644
--- a/src/liballoc/collections/btree/map.rs
+++ b/src/liballoc/collections/btree/map.rs
@@ -1328,7 +1328,10 @@ impl<'a, K: 'a, V: 'a> Iterator for IterMut<'a, K, V> {
None
} else {
self.length -= 1;
- unsafe { Some(self.range.next_unchecked()) }
+ unsafe {
+ let (k, v) = self.range.next_unchecked();
+ Some((k, v)) // coerce k from `&mut K` to `&K`
+ }
}
}
@@ -1707,7 +1710,14 @@ 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.front == self.back { None } else { unsafe { Some(self.next_unchecked()) } }
+ if self.front == self.back {
+ None
+ } else {
+ unsafe {
+ let (k, v) = self.next_unchecked();
+ Some((k, v)) // coerce k from `&mut K` to `&K`
+ }
+ }
}
fn last(mut self) -> Option<(&'a K, &'a mut V)> {
@@ -1716,7 +1726,7 @@ impl<'a, K, V> Iterator for RangeMut<'a, K, V> {
}
impl<'a, K, V> RangeMut<'a, K, V> {
- unsafe fn next_unchecked(&mut self) -> (&'a K, &'a mut V) {
+ unsafe fn next_unchecked(&mut self) -> (&'a mut K, &'a mut V) {
let handle = ptr::read(&self.front);
let mut cur_handle = match handle.right_kv() {
@@ -1724,8 +1734,7 @@ impl<'a, K, V> RangeMut<'a, K, V> {
self.front = ptr::read(&kv).right_edge();
// Doing the descend invalidates the references returned by `into_kv_mut`,
// so we have to do this last.
- let (k, v) = kv.into_kv_mut();
- return (k, v); // coerce k from `&mut K` to `&K`
+ return kv.into_kv_mut();
}
Err(last_edge) => {
let next_level = last_edge.into_node().ascend().ok();
@@ -1739,8 +1748,7 @@ impl<'a, K, V> RangeMut<'a, K, V> {
self.front = first_leaf_edge(ptr::read(&kv).right_edge().descend());
// Doing the descend invalidates the references returned by `into_kv_mut`,
// so we have to do this last.
- let (k, v) = kv.into_kv_mut();
- return (k, v); // coerce k from `&mut K` to `&K`
+ return kv.into_kv_mut();
}
Err(last_edge) => {
let next_level = last_edge.into_node().ascend().ok();
From f547978392872684085c96a3d5c1d00bad24b724 Mon Sep 17 00:00:00 2001
From: Charles Gleason <charles_gleason@alumni.brown.edu>
Date: Fri, 22 Nov 2019 14:22:06 -0500
Subject: [PATCH 2/7] Implement clone_from for BTree collections
---
src/liballoc/collections/btree/map.rs | 54 +++++++++++++++++++++++++++
src/liballoc/collections/btree/set.rs | 13 ++++++-
2 files changed, 66 insertions(+), 1 deletion(-)
diff --git a/src/liballoc/collections/btree/map.rs b/src/liballoc/collections/btree/map.rs
index e25a5e0773ec6..12174ffcbfa42 100644
--- a/src/liballoc/collections/btree/map.rs
+++ b/src/liballoc/collections/btree/map.rs
@@ -207,6 +207,60 @@ impl<K: Clone, V: Clone> Clone for BTreeMap<K, V> {
clone_subtree(self.root.as_ref())
}
}
+
+ fn clone_from(&mut self, other: &Self) {
+ BTreeClone::clone_from(self, other);
+ }
+}
+
+trait BTreeClone {
+ fn clone_from(&mut self, other: &Self);
+}
+
+impl<K: Clone, V: Clone> BTreeClone for BTreeMap<K, V> {
+ default fn clone_from(&mut self, other: &Self) {
+ *self = other.clone();
+ }
+}
+
+impl<K: Clone + Ord, V: Clone> BTreeClone for BTreeMap<K, V> {
+ fn clone_from(&mut self, other: &Self) {
+ // This truncates `self` to `other.len()` by calling `split_off` on
+ // the first key after `other.len()` elements if it exists
+ if let Some(key) = {
+ if self.len() > other.len() {
+ let diff = self.len() - other.len();
+ if diff <= other.len() {
+ self.iter().nth_back(diff - 1).map(|pair| (*pair.0).clone())
+ } else {
+ self.iter().nth(other.len()).map(|pair| (*pair.0).clone())
+ }
+ } else {
+ None
+ }
+ } {
+ self.split_off(&key);
+ }
+ let mut siter = self.range_mut(..);
+ let mut oiter = other.iter();
+ // After truncation, `self` is at most as long as `other` so this loop
+ // replaces every key-value pair in `self`. Since `oiter` is in sorted
+ // order and the structure of the `BTreeMap` stays the same,
+ // the BTree invariants are maintained at the end of the loop
+ while siter.front != siter.back {
+ if let Some((ok, ov)) = oiter.next() {
+ // This is safe because the `siter.front != siter.back` check
+ // ensures that `siter` is nonempty
+ let (sk, sv) = unsafe { siter.next_unchecked() };
+ sk.clone_from(ok);
+ sv.clone_from(ov);
+ } else {
+ break;
+ }
+ }
+ // If `other` is longer than `self`, the remaining elements are inserted
+ self.extend(oiter.map(|(k, v)| ((*k).clone(), (*v).clone())));
+ }
}
impl<K, Q: ?Sized> super::Recover<Q> for BTreeMap<K, ()>
diff --git a/src/liballoc/collections/btree/set.rs b/src/liballoc/collections/btree/set.rs
index 282d163141bc8..5bdefe5cecf1b 100644
--- a/src/liballoc/collections/btree/set.rs
+++ b/src/liballoc/collections/btree/set.rs
@@ -56,12 +56,23 @@ use crate::collections::btree_map::{self, BTreeMap, Keys};
/// println!("{}", book);
/// }
/// ```
-#[derive(Clone, Hash, PartialEq, Eq, Ord, PartialOrd)]
+#[derive(Hash, PartialEq, Eq, Ord, PartialOrd)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct BTreeSet<T> {
map: BTreeMap<T, ()>,
}
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: Clone> Clone for BTreeSet<T> {
+ fn clone(&self) -> Self {
+ BTreeSet { map: self.map.clone() }
+ }
+
+ fn clone_from(&mut self, other: &Self) {
+ self.map.clone_from(&other.map);
+ }
+}
+
/// An iterator over the items of a `BTreeSet`.
///
/// This `struct` is created by the [`iter`] method on [`BTreeSet`].
From 8651aa066fdbbcfaa082531969469c3fa289de9e Mon Sep 17 00:00:00 2001
From: Charles Gleason <charles_gleason@alumni.brown.edu>
Date: Fri, 22 Nov 2019 14:22:45 -0500
Subject: [PATCH 3/7] Add test for BTreeMap::clone_from
---
src/liballoc/tests/btree/map.rs | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/src/liballoc/tests/btree/map.rs b/src/liballoc/tests/btree/map.rs
index 3177f19927eda..65a3fbd66a4c2 100644
--- a/src/liballoc/tests/btree/map.rs
+++ b/src/liballoc/tests/btree/map.rs
@@ -554,6 +554,26 @@ fn test_clone() {
}
}
+#[test]
+fn test_clone_from() {
+ let mut map1 = BTreeMap::new();
+ let size = 30;
+
+ for i in 0..size {
+ map1.insert(i, 10 * i);
+ let mut map2 = BTreeMap::new();
+ for j in 0..i {
+ map2.insert(100 * j + 1, 2 * j + 1);
+ let mut map1_copy = map2.clone();
+ map1_copy.clone_from(&map1);
+ assert_eq!(map1_copy, map1);
+ let mut map2_copy = map1.clone();
+ map2_copy.clone_from(&map2);
+ assert_eq!(map2_copy, map2);
+ }
+ }
+}
+
#[test]
#[allow(dead_code)]
fn test_variance() {
From 3caa17b468e50c885f56e7872200e9a76815462b Mon Sep 17 00:00:00 2001
From: Charles Gleason <36055314+crgl@users.noreply.github.com>
Date: Tue, 28 Jan 2020 11:27:31 -0500
Subject: [PATCH 4/7] Format safety comment as per tidy
Co-Authored-By: Ashley Mannix <ashleymannix@live.com.au>
---
src/liballoc/collections/btree/map.rs | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/liballoc/collections/btree/map.rs b/src/liballoc/collections/btree/map.rs
index 12174ffcbfa42..58cb561938acc 100644
--- a/src/liballoc/collections/btree/map.rs
+++ b/src/liballoc/collections/btree/map.rs
@@ -249,7 +249,7 @@ impl<K: Clone + Ord, V: Clone> BTreeClone for BTreeMap<K, V> {
// the BTree invariants are maintained at the end of the loop
while siter.front != siter.back {
if let Some((ok, ov)) = oiter.next() {
- // This is safe because the `siter.front != siter.back` check
+ // SAFETY: This is safe because the `siter.front != siter.back` check
// ensures that `siter` is nonempty
let (sk, sv) = unsafe { siter.next_unchecked() };
sk.clone_from(ok);
From 60a7c9421e78a29610e019b4030ca011bcd0bfd5 Mon Sep 17 00:00:00 2001
From: Charles Gleason <charles_gleason@alumni.brown.edu>
Date: Tue, 28 Jan 2020 11:39:48 -0500
Subject: [PATCH 5/7] Include empty BTreeMap in clone_from tests
---
src/liballoc/tests/btree/map.rs | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/src/liballoc/tests/btree/map.rs b/src/liballoc/tests/btree/map.rs
index 65a3fbd66a4c2..cd9daf41eb1ed 100644
--- a/src/liballoc/tests/btree/map.rs
+++ b/src/liballoc/tests/btree/map.rs
@@ -560,17 +560,17 @@ fn test_clone_from() {
let size = 30;
for i in 0..size {
- map1.insert(i, 10 * i);
let mut map2 = BTreeMap::new();
for j in 0..i {
- map2.insert(100 * j + 1, 2 * j + 1);
let mut map1_copy = map2.clone();
map1_copy.clone_from(&map1);
assert_eq!(map1_copy, map1);
let mut map2_copy = map1.clone();
map2_copy.clone_from(&map2);
assert_eq!(map2_copy, map2);
+ map2.insert(100 * j + 1, 2 * j + 1);
}
+ map1.insert(i, 10 * i);
}
}
From 81b6f8c3fc9098e7b1b6aad230ea7770d03070bc Mon Sep 17 00:00:00 2001
From: Charles Gleason <charles_gleason@alumni.brown.edu>
Date: Tue, 28 Jan 2020 11:46:49 -0500
Subject: [PATCH 6/7] Add private is_empty method to RangeMut
---
src/liballoc/collections/btree/map.rs | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/src/liballoc/collections/btree/map.rs b/src/liballoc/collections/btree/map.rs
index 58cb561938acc..d0c56d83d722a 100644
--- a/src/liballoc/collections/btree/map.rs
+++ b/src/liballoc/collections/btree/map.rs
@@ -247,7 +247,7 @@ impl<K: Clone + Ord, V: Clone> BTreeClone for BTreeMap<K, V> {
// replaces every key-value pair in `self`. Since `oiter` is in sorted
// order and the structure of the `BTreeMap` stays the same,
// the BTree invariants are maintained at the end of the loop
- while siter.front != siter.back {
+ while !siter.is_empty() {
if let Some((ok, ov)) = oiter.next() {
// SAFETY: This is safe because the `siter.front != siter.back` check
// ensures that `siter` is nonempty
@@ -1764,7 +1764,7 @@ 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.front == self.back {
+ if self.is_empty() {
None
} else {
unsafe {
@@ -1780,6 +1780,10 @@ 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 mut K, &'a mut V) {
let handle = ptr::read(&self.front);
@@ -1816,7 +1820,7 @@ impl<'a, K, V> RangeMut<'a, K, V> {
#[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.front == self.back { None } else { unsafe { Some(self.next_back_unchecked()) } }
+ if self.is_empty() { None } else { unsafe { Some(self.next_back_unchecked()) } }
}
}
From 6c3e477d134511094ab301fc15c504cc79804e41 Mon Sep 17 00:00:00 2001
From: Charles Gleason <charles_gleason@alumni.brown.edu>
Date: Tue, 28 Jan 2020 11:59:50 -0500
Subject: [PATCH 7/7] Reformat truncation section of clone_from
---
src/liballoc/collections/btree/map.rs | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)
diff --git a/src/liballoc/collections/btree/map.rs b/src/liballoc/collections/btree/map.rs
index d0c56d83d722a..7c45a6fe49823 100644
--- a/src/liballoc/collections/btree/map.rs
+++ b/src/liballoc/collections/btree/map.rs
@@ -227,20 +227,20 @@ impl<K: Clone + Ord, V: Clone> BTreeClone for BTreeMap<K, V> {
fn clone_from(&mut self, other: &Self) {
// This truncates `self` to `other.len()` by calling `split_off` on
// the first key after `other.len()` elements if it exists
- if let Some(key) = {
- if self.len() > other.len() {
- let diff = self.len() - other.len();
- if diff <= other.len() {
- self.iter().nth_back(diff - 1).map(|pair| (*pair.0).clone())
- } else {
- self.iter().nth(other.len()).map(|pair| (*pair.0).clone())
- }
+ let split_off_key = if self.len() > other.len() {
+ let diff = self.len() - other.len();
+ if diff <= other.len() {
+ self.iter().nth_back(diff - 1).map(|pair| (*pair.0).clone())
} else {
- None
+ self.iter().nth(other.len()).map(|pair| (*pair.0).clone())
}
- } {
+ } else {
+ None
+ };
+ if let Some(key) = split_off_key {
self.split_off(&key);
}
+
let mut siter = self.range_mut(..);
let mut oiter = other.iter();
// After truncation, `self` is at most as long as `other` so this loop