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std::io: Modify some ReadBuf method signatures to return &mut Self

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This allows using `ReadBuf` in a builder-like style and to setup a `ReadBuf` and
pass it to `read_buf` in a single expression, e.g.,

```
// With this PR:
reader.read_buf(ReadBuf::uninit(buf).assume_init(init_len))?;

// Previously:
let mut buf = ReadBuf::uninit(buf);
buf.assume_init(init_len);
reader.read_buf(&mut buf)?;
```

Signed-off-by: Nick Cameron <nrc@ncameron.org>
This commit is contained in:
Nick Cameron 2022-04-07 15:56:25 +01:00
parent 3d237ab529
commit a3c30e440a
1 changed files with 11 additions and 7 deletions
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18
library/std/src/io/readbuf.rs
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@ -166,8 +166,8 @@ pub fn remaining(&self) -> usize {
///
/// The number of initialized bytes is not changed, and the contents of the buffer are not modified.
#[inline]
pub fn clear(&mut self) {
self.set_filled(0); // The assertion in `set_filled` is optimized out
pub fn clear(&mut self) -> &mut Self {
self.set_filled(0) // The assertion in `set_filled` is optimized out
}
/// Increases the size of the filled region of the buffer.
@ -178,8 +178,8 @@ pub fn clear(&mut self) {
///
/// Panics if the filled region of the buffer would become larger than the initialized region.
#[inline]
pub fn add_filled(&mut self, n: usize) {
self.set_filled(self.filled + n);
pub fn add_filled(&mut self, n: usize) -> &mut Self {
self.set_filled(self.filled + n)
}
/// Sets the size of the filled region of the buffer.
@ -193,10 +193,11 @@ pub fn add_filled(&mut self, n: usize) {
///
/// Panics if the filled region of the buffer would become larger than the initialized region.
#[inline]
pub fn set_filled(&mut self, n: usize) {
pub fn set_filled(&mut self, n: usize) -> &mut Self {
assert!(n <= self.initialized);
self.filled = n;
self
}
/// Asserts that the first `n` unfilled bytes of the buffer are initialized.
@ -208,8 +209,9 @@ pub fn set_filled(&mut self, n: usize) {
///
/// The caller must ensure that the first `n` unfilled bytes of the buffer have already been initialized.
#[inline]
pub unsafe fn assume_init(&mut self, n: usize) {
pub unsafe fn assume_init(&mut self, n: usize) -> &mut Self {
self.initialized = cmp::max(self.initialized, self.filled + n);
self
}
/// Appends data to the buffer, advancing the written position and possibly also the initialized position.
@ -227,7 +229,9 @@ pub fn append(&mut self, buf: &[u8]) {
}
// SAFETY: We just added the entire contents of buf to the filled section.
unsafe { self.assume_init(buf.len()) }
unsafe {
self.assume_init(buf.len());
}
self.add_filled(buf.len());
}