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Fix reverse iteration in cretonne-entity's Iter.

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A `DoubleEndedIterator` needs to track both a forward position and a
reverse position, so that `next_back()` can pop from the back of the
sequence.
This commit is contained in:
Dan Gohman
2018-05-29 16:53:34 -07:00
parent 09fb914823
commit 7720a571fc
5 changed files with 92 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

20
lib/entity/src/iter.rs
View File

@@ -10,6 +10,7 @@ where
V: 'a,
{
pos: usize,
rev_pos: usize,
iter: slice::Iter<'a, V>,
unused: PhantomData<K>,
}
@@ -17,9 +18,10 @@ where
impl<'a, K: EntityRef, V> Iter<'a, K, V> {
/// Create an `Iter` iterator that visits the `PrimaryMap` keys and values
/// of `iter`.
pub fn new(key: K, iter: slice::Iter<'a, V>) -> Self {
pub fn new(iter: slice::Iter<'a, V>) -> Self {
Self {
pos: key.index(),
pos: 0,
rev_pos: iter.len(),
iter,
unused: PhantomData,
}
@@ -47,7 +49,9 @@ impl<'a, K: EntityRef, V> Iterator for Iter<'a, K, V> {
impl<'a, K: EntityRef, V> DoubleEndedIterator for Iter<'a, K, V> {
fn next_back(&mut self) -> Option<Self::Item> {
if let Some(next_back) = self.iter.next_back() {
Some((K::new(self.pos), next_back))
let rev_pos = self.rev_pos - 1;
self.rev_pos -= 1;
Some((K::new(rev_pos), next_back))
} else {
None
}
@@ -62,6 +66,7 @@ where
V: 'a,
{
pos: usize,
rev_pos: usize,
iter: slice::IterMut<'a, V>,
unused: PhantomData<K>,
}
@@ -69,9 +74,10 @@ where
impl<'a, K: EntityRef, V> IterMut<'a, K, V> {
/// Create an `IterMut` iterator that visits the `PrimaryMap` keys and values
/// of `iter`.
pub fn new(key: K, iter: slice::IterMut<'a, V>) -> Self {
pub fn new(iter: slice::IterMut<'a, V>) -> Self {
Self {
pos: key.index(),
pos: 0,
rev_pos: iter.len(),
iter,
unused: PhantomData,
}
@@ -99,7 +105,9 @@ impl<'a, K: EntityRef, V> Iterator for IterMut<'a, K, V> {
impl<'a, K: EntityRef, V> DoubleEndedIterator for IterMut<'a, K, V> {
fn next_back(&mut self) -> Option<Self::Item> {
if let Some(next_back) = self.iter.next_back() {
Some((K::new(self.pos), next_back))
let rev_pos = self.rev_pos - 1;
self.rev_pos -= 1;
Some((K::new(rev_pos), next_back))
} else {
None
}

6
lib/entity/src/keys.rs
View File

@@ -11,11 +11,11 @@ pub struct Keys<K: EntityRef> {
}
impl<K: EntityRef> Keys<K> {
/// Create a `Keys` iterator that visits `count` entities starting from 0.
pub fn new(count: usize) -> Self {
/// Create a `Keys` iterator that visits `len` entities starting from 0.
pub fn with_len(len: usize) -> Self {
Self {
pos: 0,
rev_pos: count,
rev_pos: len,
unused: PhantomData,
}
}

6
lib/entity/src/map.rs
View File

@@ -71,17 +71,17 @@ where
/// Iterate over all the keys and values in this map.
pub fn iter(&self) -> Iter<K, V> {
Iter::new(K::new(0), self.elems.iter())
Iter::new(self.elems.iter())
}
/// Iterate over all the keys and values in this map, mutable edition.
pub fn iter_mut(&mut self) -> IterMut<K, V> {
IterMut::new(K::new(0), self.elems.iter_mut())
IterMut::new(self.elems.iter_mut())
}
/// Iterate over all the keys in this map.
pub fn keys(&self) -> Keys<K> {
Keys::new(self.elems.len())
Keys::with_len(self.elems.len())
}
/// Iterate over all the keys in this map.

74
lib/entity/src/primary.rs
View File

@@ -57,7 +57,7 @@ where
/// Iterate over all the keys in this map.
pub fn keys(&self) -> Keys<K> {
Keys::new(self.elems.len())
Keys::with_len(self.elems.len())
}
/// Iterate over all the values in this map.
@@ -72,12 +72,12 @@ where
/// Iterate over all the keys and values in this map.
pub fn iter(&self) -> Iter<K, V> {
Iter::new(K::new(0), self.elems.iter())
Iter::new(self.elems.iter())
}
/// Iterate over all the keys and values in this map, mutable edition.
pub fn iter_mut(&mut self) -> IterMut<K, V> {
IterMut::new(K::new(0), self.elems.iter_mut())
IterMut::new(self.elems.iter_mut())
}
/// Remove all entries from this map.
@@ -192,6 +192,34 @@ mod tests {
}
}
#[test]
fn iter_rev() {
let mut m: PrimaryMap<E, usize> = PrimaryMap::new();
m.push(12);
m.push(33);
let mut i = 2;
for (key, value) in m.iter().rev() {
i -= 1;
assert_eq!(key.index(), i);
match i {
0 => assert_eq!(*value, 12),
1 => assert_eq!(*value, 33),
_ => panic!(),
}
}
i = 2;
for (key, value) in m.iter_mut().rev() {
i -= 1;
assert_eq!(key.index(), i);
match i {
0 => assert_eq!(*value, 12),
1 => assert_eq!(*value, 33),
_ => panic!(),
}
}
}
#[test]
fn keys() {
let mut m: PrimaryMap<E, usize> = PrimaryMap::new();
@@ -205,6 +233,19 @@ mod tests {
}
}
#[test]
fn keys_rev() {
let mut m: PrimaryMap<E, usize> = PrimaryMap::new();
m.push(12);
m.push(33);
let mut i = 2;
for key in m.keys().rev() {
i -= 1;
assert_eq!(key.index(), i);
}
}
#[test]
fn values() {
let mut m: PrimaryMap<E, usize> = PrimaryMap::new();
@@ -230,4 +271,31 @@ mod tests {
i += 1;
}
}
#[test]
fn values_rev() {
let mut m: PrimaryMap<E, usize> = PrimaryMap::new();
m.push(12);
m.push(33);
let mut i = 2;
for value in m.values().rev() {
i -= 1;
match i {
0 => assert_eq!(*value, 12),
1 => assert_eq!(*value, 33),
_ => panic!(),
}
}
i = 2;
for value_mut in m.values_mut().rev() {
i -= 1;
match i {
0 => assert_eq!(*value_mut, 12),
1 => assert_eq!(*value_mut, 33),
_ => panic!(),
}
}
}
}

2
lib/entity/src/set.rs
View File

@@ -55,7 +55,7 @@ where
/// Iterate over all the keys in this set.
pub fn keys(&self) -> Keys<K> {
Keys::new(self.len)
Keys::with_len(self.len)
}
/// Resize the set to have `n` entries by adding default entries as needed.