1use std::io::IoSlice;
2use std::ops::Deref;
3use std::slice;
4
5pub struct IoBufs<'a, 'b>(&'b mut [IoSlice<'a>]);
6
7impl<'a, 'b> IoBufs<'a, 'b> {
8 pub fn new(slices: &'b mut [IoSlice<'a>]) -> Self {
9 IoBufs(slices)
10 }
11
12 pub fn is_empty(&self) -> bool {
13 self.0.is_empty()
14 }
15
16 pub fn advance(mut self, n: usize) -> IoBufs<'a, 'b> {
17 let mut to_remove = 0;
18 let mut remaining_len = n;
19 for slice in self.0.iter() {
20 if remaining_len < slice.len() {
21 break;
22 } else {
23 remaining_len -= slice.len();
24 to_remove += 1;
25 }
26 }
27 self.0 = self.0.split_at_mut(to_remove).1;
28 if let Some(slice) = self.0.first_mut() {
29 let tail = &slice[remaining_len..];
30 // Safety: recasts slice to the original lifetime
31 let tail = unsafe { slice::from_raw_parts(tail.as_ptr(), tail.len()) };
32 *slice = IoSlice::new(tail);
33 } else if remaining_len != 0 {
34 panic!("advance past the end of the slice vector");
35 }
36 self
37 }
38}
39
40impl<'a, 'b> Deref for IoBufs<'a, 'b> {
41 type Target = [IoSlice<'a>];
42 fn deref(&self) -> &[IoSlice<'a>] {
43 self.0
44 }
45}
46