workspace: move crates under crates

crates/utils/src/vec_ext.rs

@@ -0,0 +1,40 @@
+use std::{mem::MaybeUninit, ops::Range, slice};
+
+pub trait VecExt<T> {
+    fn split_at_spare_mut_ext(&mut self) -> (&mut [T], &mut [MaybeUninit<T>]);
+    fn split_at_spare_mut_bytes_ext(&mut self) -> (&mut [T], &mut [MaybeUninit<u8>]);
+}
+
+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)
+        }
+    }
+
+    fn split_at_spare_mut_bytes_ext(&mut self) -> (&mut [T], &mut [MaybeUninit<u8>]) {
+        let (l, r) = self.split_at_spare_mut_ext();
+        unsafe { (l, uapi::as_maybe_uninit_bytes_mut2(r)) }
+    }
+}
+
+pub trait UninitVecExt<T> {
+    fn set_len_safe(&mut self, n: usize);
+}
+
+impl<T> UninitVecExt<T> for Vec<MaybeUninit<T>> {
+    fn set_len_safe(&mut self, n: usize) {
+        assert!(n <= self.capacity());
+        unsafe {
+            self.set_len(n);
+        }
+    }
+}