gix_utils/
buffers.rs

1use crate::Buffers;
2
3/// Lifecycle
4impl Buffers {
5    /// Use this if there is an input buffer `src` which isn't owned by you, but which should be used as source when
6    /// asking for [`src_and_dest()`](WithForeignSource::src_and_dest()).
7    pub fn use_foreign_src<'a, 'src>(&'a mut self, src: &'src [u8]) -> WithForeignSource<'src, 'a> {
8        self.clear();
9        WithForeignSource {
10            ro_src: Some(src),
11            src: &mut self.src,
12            dest: &mut self.dest,
13        }
14    }
15}
16
17impl Buffers {
18    /// Clear all buffers, which should be called once processing is done.
19    pub fn clear(&mut self) {
20        self.src.clear();
21        self.dest.clear();
22    }
23
24    /// Must be called after every change (i.e. when it's known that `dest` was written.
25    pub fn swap(&mut self) {
26        std::mem::swap(&mut self.src, &mut self.dest);
27    }
28}
29
30/// A utility to do buffer-swapping with, similar to [`Buffers`], but with support for a
31/// read-only one-time buffer as source.
32pub struct WithForeignSource<'src, 'bufs> {
33    /// The original source buffer, or `None` if already altered.
34    pub ro_src: Option<&'src [u8]>,
35    /// The source buffer that will be used after the first call to `swap`.
36    pub src: &'bufs mut Vec<u8>,
37    dest: &'bufs mut Vec<u8>,
38}
39
40impl WithForeignSource<'_, '_> {
41    /// Must be called after every change (i.e. when it's known that `dest` was written.
42    pub fn swap(&mut self) {
43        self.ro_src.take();
44        std::mem::swap(&mut self.src, &mut self.dest);
45        self.dest.clear();
46    }
47    /// Obtain `(source, destination)`, which reads from the read-only source exactly once.
48    pub fn src_and_dest(&mut self) -> (&[u8], &mut Vec<u8>) {
49        match self.ro_src {
50            Some(src) => (src, &mut self.dest),
51            None => (self.src, &mut self.dest),
52        }
53    }
54}
gix_utils/buffers.rs

gix_utils/
buffers.rs
