Struct std::io::BorrowedCursor
source · pub struct BorrowedCursor<'a> { /* private fields */ }
read_buf
#78485)Expand description
A writeable view of the unfilled portion of a BorrowedBuf
.
Provides access to the initialized and uninitialized parts of the underlying 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
sourceimpl<'a> BorrowedCursor<'a>
impl<'a> BorrowedCursor<'a>
sourcepub fn reborrow<'this>(&'this mut self) -> BorrowedCursor<'this>ⓘ
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pub fn reborrow<'this>(&'this mut self) -> BorrowedCursor<'this>ⓘ
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#78485)Reborrow 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
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pub fn capacity(&self) -> usize
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#78485)Returns the available space in the cursor.
sourcepub fn written(&self) -> usize
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pub fn written(&self) -> usize
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#78485)Returns the number of bytes written to this cursor since it was created from a BorrowedBuf
.
Note that if this cursor is a reborrowed clone of another, then the count returned is the count written via either cursor, not the count since the cursor was reborrowed.
sourcepub fn init_ref(&self) -> &[u8]ⓘ
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pub fn init_ref(&self) -> &[u8]ⓘ
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#78485)Returns a shared reference to the initialized portion of the cursor.
sourcepub fn init_mut(&mut self) -> &mut [u8]ⓘ
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pub fn init_mut(&mut self) -> &mut [u8]ⓘ
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#78485)Returns a mutable reference to the initialized portion of the cursor.
sourcepub fn uninit_mut(&mut self) -> &mut [MaybeUninit<u8>]
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pub fn uninit_mut(&mut self) -> &mut [MaybeUninit<u8>]
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#78485)Returns a mutable reference to the uninitialized part of the cursor.
It is safe to uninitialize any of these bytes.
sourcepub unsafe fn as_mut(&mut self) -> &mut [MaybeUninit<u8>]
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pub unsafe fn as_mut(&mut self) -> &mut [MaybeUninit<u8>]
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#78485)Returns a mutable reference to the whole cursor.
Safety
The caller must not uninitialize any bytes in the initialized portion of the cursor.
sourcepub unsafe fn advance(&mut self, n: usize) -> &mut Self
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pub unsafe fn advance(&mut self, n: usize) -> &mut Self
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#78485)Advance 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 Self
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pub fn ensure_init(&mut self) -> &mut Self
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#78485)Initializes all bytes in the cursor.
sourcepub unsafe fn set_init(&mut self, n: usize) -> &mut Self
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pub unsafe fn set_init(&mut self, n: usize) -> &mut Self
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#78485)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.
Trait Implementations
sourceimpl<'a> Debug for BorrowedCursor<'a>
impl<'a> Debug for BorrowedCursor<'a>
sourceimpl<'a> Write for BorrowedCursor<'a>
impl<'a> Write for BorrowedCursor<'a>
sourcefn write(&mut self, buf: &[u8]) -> Result<usize>
fn write(&mut self, buf: &[u8]) -> Result<usize>
sourcefn flush(&mut self) -> Result<()>
fn flush(&mut self) -> Result<()>
1.36.0 · sourcefn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize>
fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize>
sourcefn is_write_vectored(&self) -> bool
fn is_write_vectored(&self) -> bool
can_vector
#69941)1.0.0 · sourcefn write_all(&mut self, buf: &[u8]) -> Result<()>
fn write_all(&mut self, buf: &[u8]) -> Result<()>
sourcefn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<()>
fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<()>
write_all_vectored
#70436)