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Auto merge of #95770 - nrc:read-buf-builder, r=joshtriplett

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

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)?;
```

r? `@sfackler`

cc https://github.com/rust-lang/rust/issues/78485, https://github.com/rust-lang/rust/issues/94741
This commit is contained in:
bors 2022-06-10 03:55:16 +00:00
commit 52ee2a2738
1 changed files with 11 additions and 7 deletions
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18
library/std/src/io/readbuf.rs
View file

@ -166,8 +166,8 @@ impl<'a> ReadBuf<'a> {
/// ///
/// The number of initialized bytes is not changed, and the contents of the buffer are not modified. /// The number of initialized bytes is not changed, and the contents of the buffer are not modified.
#[inline] #[inline]
pub fn clear(&mut self) { pub fn clear(&mut self) -> &mut Self {
self.set_filled(0); // The assertion in `set_filled` is optimized out self.set_filled(0) // The assertion in `set_filled` is optimized out
} }
/// Increases the size of the filled region of the buffer. /// Increases the size of the filled region of the buffer.
@ -178,8 +178,8 @@ impl<'a> ReadBuf<'a> {
/// ///
/// Panics if the filled region of the buffer would become larger than the initialized region. /// Panics if the filled region of the buffer would become larger than the initialized region.
#[inline] #[inline]
pub fn add_filled(&mut self, n: usize) { pub fn add_filled(&mut self, n: usize) -> &mut Self {
self.set_filled(self.filled + n); self.set_filled(self.filled + n)
} }
/// Sets the size of the filled region of the buffer. /// Sets the size of the filled region of the buffer.
@ -193,10 +193,11 @@ impl<'a> ReadBuf<'a> {
/// ///
/// Panics if the filled region of the buffer would become larger than the initialized region. /// Panics if the filled region of the buffer would become larger than the initialized region.
#[inline] #[inline]
pub fn set_filled(&mut self, n: usize) { pub fn set_filled(&mut self, n: usize) -> &mut Self {
assert!(n <= self.initialized); assert!(n <= self.initialized);
self.filled = n; self.filled = n;
self
} }
/// Asserts that the first `n` unfilled bytes of the buffer are initialized. /// Asserts that the first `n` unfilled bytes of the buffer are initialized.
@ -208,8 +209,9 @@ impl<'a> ReadBuf<'a> {
/// ///
/// The caller must ensure that the first `n` unfilled bytes of the buffer have already been initialized. /// The caller must ensure that the first `n` unfilled bytes of the buffer have already been initialized.
#[inline] #[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.initialized = cmp::max(self.initialized, self.filled + n);
self
} }
/// Appends data to the buffer, advancing the written position and possibly also the initialized position. /// Appends data to the buffer, advancing the written position and possibly also the initialized position.
@ -227,7 +229,9 @@ impl<'a> ReadBuf<'a> {
} }
// SAFETY: We just added the entire contents of buf to the filled section. // 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()); self.add_filled(buf.len());
} }