refactor: VecDeques IntoIter fields to private

[rust.git] / library / alloc / src / collections / vec_deque / mod.rs

diff --git a/library/alloc/src/collections/vec_deque/mod.rs b/library/alloc/src/collections/vec_deque/mod.rs
index 9a2205420a14b095781c2d06fff6300b91cbeb98..10144cc17bf306579ccc1b4e2272fb86b11a644d 100644 (file)
--- a/library/alloc/src/collections/vec_deque/mod.rs
+++ b/library/alloc/src/collections/vec_deque/mod.rs
@@ -2129,16 +2129,32 @@ pub fn retain<F>(&mut self, mut f: F)
         F: FnMut(&T) -> bool,
     {
         let len = self.len();
-        let mut del = 0;
-        for i in 0..len {
-            if !f(&self[i]) {
-                del += 1;
-            } else if del > 0 {
-                self.swap(i - del, i);
+        let mut idx = 0;
+        let mut cur = 0;
+
+        // Stage 1: All values are retained.
+        while cur < len {
+            if !f(&self[cur]) {
+                cur += 1;
+                break;
             }
+            cur += 1;
+            idx += 1;
         }
-        if del > 0 {
-            self.truncate(len - del);
+        // Stage 2: Swap retained value into current idx.
+        while cur < len {
+            if !f(&self[cur]) {
+                cur += 1;
+                continue;
+            }
+
+            self.swap(idx, cur);
+            cur += 1;
+            idx += 1;
+        }
+        // Stage 3: Trancate all values after idx.
+        if cur != idx {
+            self.truncate(idx);
         }
     }
 
@@ -2811,7 +2827,7 @@ impl<T, A: Allocator> IntoIterator for VecDeque<T, A> {
     /// Consumes the `VecDeque` into a front-to-back iterator yielding elements by
     /// value.
     fn into_iter(self) -> IntoIter<T, A> {
-        IntoIter { inner: self }
+        IntoIter::new(self)
     }
 }