pub struct BorrowedCursor<'a> { /* private fields */ }core_io_borrowed_buf)Expand description
A writeable view of the unfilled portion of a BorrowedBuf.
The unfilled portion consists of an initialized and an uninitialized part; see BorrowedBuf
for details.
Data can be written directly to the cursor by using append or
indirectly by getting a slice of part or all of the cursor and writing into the slice. In the
indirect case, the caller must call advance after writing to inform
the cursor how many bytes have been written.
Once data is written to the cursor, it becomes part of the filled portion of the underlying
BorrowedBuf and can no longer be accessed or re-written by the cursor. I.e., the cursor tracks
the unfilled part of the underlying BorrowedBuf.
The lifetime 'a is a bound on the lifetime of the underlying buffer (which means it is a bound
on the data in that buffer by transitivity).
Implementations§
Source§impl<'a> BorrowedCursor<'a>
impl<'a> BorrowedCursor<'a>
Sourcepub fn reborrow<'this>(&'this mut self) -> BorrowedCursor<'this> ⓘ
🔬This is a nightly-only experimental API. (core_io_borrowed_buf)
pub fn reborrow<'this>(&'this mut self) -> BorrowedCursor<'this> ⓘ
core_io_borrowed_buf)Reborrows this cursor by cloning it with a smaller lifetime.
Since a cursor maintains unique access to its underlying buffer, the borrowed cursor is not accessible while the new cursor exists.
Sourcepub fn capacity(&self) -> usize
🔬This is a nightly-only experimental API. (core_io_borrowed_buf)
pub fn capacity(&self) -> usize
core_io_borrowed_buf)Returns the available space in the cursor.
Sourcepub fn written(&self) -> usize
🔬This is a nightly-only experimental API. (core_io_borrowed_buf)
pub fn written(&self) -> usize
core_io_borrowed_buf)Returns the number of bytes written to the BorrowedBuf this cursor was created from.
In particular, the count returned is shared by all reborrows of the cursor.
Sourcepub fn init_mut(&mut self) -> &mut [u8] ⓘ
🔬This is a nightly-only experimental API. (core_io_borrowed_buf)
pub fn init_mut(&mut self) -> &mut [u8] ⓘ
core_io_borrowed_buf)Returns a mutable reference to the initialized portion of the cursor.
Sourcepub unsafe fn as_mut(&mut self) -> &mut [MaybeUninit<u8>]
🔬This is a nightly-only experimental API. (core_io_borrowed_buf)
pub unsafe fn as_mut(&mut self) -> &mut [MaybeUninit<u8>]
core_io_borrowed_buf)Returns a mutable reference to the whole cursor.
§Safety
The caller must not uninitialize any bytes in the initialized portion of the cursor.
Sourcepub fn advance(&mut self, n: usize) -> &mut BorrowedCursor<'a> ⓘ
🔬This is a nightly-only experimental API. (core_io_borrowed_buf)
pub fn advance(&mut self, n: usize) -> &mut BorrowedCursor<'a> ⓘ
core_io_borrowed_buf)Advances the cursor by asserting that n bytes have been filled.
After advancing, the n bytes are no longer accessible via the cursor and can only be
accessed via the underlying buffer. I.e., the buffer’s filled portion grows by n elements
and its unfilled portion (and the capacity of this cursor) shrinks by n elements.
If less than n bytes initialized (by the cursor’s point of view), set_init should be
called first.
§Panics
Panics if there are less than n bytes initialized.
Sourcepub unsafe fn advance_unchecked(&mut self, n: usize) -> &mut BorrowedCursor<'a> ⓘ
🔬This is a nightly-only experimental API. (core_io_borrowed_buf)
pub unsafe fn advance_unchecked(&mut self, n: usize) -> &mut BorrowedCursor<'a> ⓘ
core_io_borrowed_buf)Advances the cursor by asserting that n bytes have been filled.
After advancing, the n bytes are no longer accessible via the cursor and can only be
accessed via the underlying buffer. I.e., the buffer’s filled portion grows by n elements
and its unfilled portion (and the capacity of this cursor) shrinks by n elements.
§Safety
The caller must ensure that the first n bytes of the cursor have been properly
initialised.
Sourcepub fn ensure_init(&mut self) -> &mut BorrowedCursor<'a> ⓘ
🔬This is a nightly-only experimental API. (core_io_borrowed_buf)
pub fn ensure_init(&mut self) -> &mut BorrowedCursor<'a> ⓘ
core_io_borrowed_buf)Initializes all bytes in the cursor.
Sourcepub unsafe fn set_init(&mut self, n: usize) -> &mut BorrowedCursor<'a> ⓘ
🔬This is a nightly-only experimental API. (core_io_borrowed_buf)
pub unsafe fn set_init(&mut self, n: usize) -> &mut BorrowedCursor<'a> ⓘ
core_io_borrowed_buf)Asserts that the first n unfilled bytes of the cursor are initialized.
BorrowedBuf assumes that bytes are never de-initialized, so this method does nothing when
called with fewer bytes than are already known to be initialized.
§Safety
The caller must ensure that the first n bytes of the buffer have already been initialized.
Sourcepub fn append(&mut self, buf: &[u8])
🔬This is a nightly-only experimental API. (core_io_borrowed_buf)
pub fn append(&mut self, buf: &[u8])
core_io_borrowed_buf)Appends data to the cursor, advancing position within its buffer.
§Panics
Panics if self.capacity() is less than buf.len().
Sourcepub fn with_unfilled_buf<T>(
&mut self,
f: impl FnOnce(&mut BorrowedBuf<'_>) -> T,
) -> T
🔬This is a nightly-only experimental API. (core_io_borrowed_buf)
pub fn with_unfilled_buf<T>( &mut self, f: impl FnOnce(&mut BorrowedBuf<'_>) -> T, ) -> T
core_io_borrowed_buf)Runs the given closure with a BorrowedBuf containing the unfilled part
of the cursor.
This enables inspecting what was written to the cursor.
§Panics
Panics if the BorrowedBuf given to the closure is replaced by another
one.
Trait Implementations§
Source§impl<'a> Debug for BorrowedCursor<'a>
impl<'a> Debug for BorrowedCursor<'a>
Source§impl<'data> From<BorrowedCursor<'data>> for BorrowedBuf<'data>
Creates a new BorrowedBuf from a cursor.
impl<'data> From<BorrowedCursor<'data>> for BorrowedBuf<'data>
Creates a new BorrowedBuf from a cursor.
Use BorrowedCursor::with_unfilled_buf instead for a safer alternative.
Source§fn from(buf: BorrowedCursor<'data>) -> BorrowedBuf<'data>
fn from(buf: BorrowedCursor<'data>) -> BorrowedBuf<'data>
Source§impl<'a> Write for BorrowedCursor<'a>
impl<'a> Write for BorrowedCursor<'a>
Source§fn write(&mut self, buf: &[u8]) -> Result<usize, Error>
fn write(&mut self, buf: &[u8]) -> Result<usize, Error>
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write_all_vectored)Source§fn flush(&mut self) -> Result<(), Error>
fn flush(&mut self) -> Result<(), Error>
Auto Trait Implementations§
impl<'a> Freeze for BorrowedCursor<'a>
impl<'a> RefUnwindSafe for BorrowedCursor<'a>
impl<'a> Send for BorrowedCursor<'a>
impl<'a> Sync for BorrowedCursor<'a>
impl<'a> Unpin for BorrowedCursor<'a>
impl<'a> !UnwindSafe for BorrowedCursor<'a>
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