pub struct BorrowedCursor<'a> { /* private fields */ }core_io_borrowed_buf #117693)Expand description
A writeable view of the unfilled portion of a BorrowedBuf.
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 #117693)
pub fn reborrow<'this>(&'this mut self) -> BorrowedCursor<'this>
core_io_borrowed_buf #117693)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 #117693)
pub fn capacity(&self) -> usize
core_io_borrowed_buf #117693)Returns the available space in the cursor.
Sourcepub fn written(&self) -> usize
🔬This is a nightly-only experimental API. (core_io_borrowed_buf #117693)
pub fn written(&self) -> usize
core_io_borrowed_buf #117693)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 unsafe fn as_mut(&mut self) -> &mut [MaybeUninit<u8>]
🔬This is a nightly-only experimental API. (core_io_borrowed_buf #117693)
pub unsafe fn as_mut(&mut self) -> &mut [MaybeUninit<u8>]
core_io_borrowed_buf #117693)Returns a mutable reference to the whole cursor.
§Safety
The caller must not uninitialize any previously initialized bytes.
Sourcepub unsafe fn advance(&mut self, n: usize) -> &mut Self
🔬This is a nightly-only experimental API. (core_io_borrowed_buf #117693)
pub unsafe fn advance(&mut self, n: usize) -> &mut Self
core_io_borrowed_buf #117693)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 initialized. n
must not exceed the remaining capacity of this cursor.
Sourcepub fn append(&mut self, buf: &[u8])
🔬This is a nightly-only experimental API. (core_io_borrowed_buf #117693)
pub fn append(&mut self, buf: &[u8])
core_io_borrowed_buf #117693)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 #117693)
pub fn with_unfilled_buf<T>( &mut self, f: impl FnOnce(&mut BorrowedBuf<'_>) -> T, ) -> T
core_io_borrowed_buf #117693)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.