autocommit 2022-01-02 15:13:33 CET

src/utils/vec_ext.rs

@@ -0,0 +1,23 @@
+use std::mem::MaybeUninit;
+use std::ops::Range;
+use std::slice;
+
+pub trait VecExt<T> {
+    fn split_at_spare_mut_ext(&mut self) -> (&mut [T], &mut [MaybeUninit<T>]);
+}
+
+impl<T> VecExt<T> for Vec<T> {
+    fn split_at_spare_mut_ext(&mut self) -> (&mut [T], &mut [MaybeUninit<T>]) {
+        let Range {
+            start: ptr,
+            end: spare_ptr,
+        } = self.as_mut_ptr_range();
+        let spare_ptr = spare_ptr.cast::<MaybeUninit<T>>();
+        let spare_len = self.capacity() - self.len();
+        unsafe {
+            let initialized = slice::from_raw_parts_mut(ptr, self.len());
+            let spare = slice::from_raw_parts_mut(spare_ptr, spare_len);
+            (initialized, spare)
+        }
+    }
+}