Struct std::io::BorrowedCursor

source ·
pub struct BorrowedCursor<'a> { /* private fields */ }
🔬This is a nightly-only experimental API. (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§

🔬This is a nightly-only experimental API. (read_buf #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.

🔬This is a nightly-only experimental API. (read_buf #78485)

Returns the available space in the cursor.

🔬This is a nightly-only experimental API. (read_buf #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.

🔬This is a nightly-only experimental API. (read_buf #78485)

Returns a shared reference to the initialized portion of the cursor.

🔬This is a nightly-only experimental API. (read_buf #78485)

Returns a mutable reference to the initialized portion of the cursor.

🔬This is a nightly-only experimental API. (read_buf #78485)

Returns a mutable reference to the uninitialized part of the cursor.

It is safe to uninitialize any of these bytes.

🔬This is a nightly-only experimental API. (read_buf #78485)

Returns a mutable reference to the whole cursor.

Safety

The caller must not uninitialize any bytes in the initialized portion of the cursor.

🔬This is a nightly-only experimental API. (read_buf #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.

🔬This is a nightly-only experimental API. (read_buf #78485)

Initializes all bytes in the cursor.

🔬This is a nightly-only experimental API. (read_buf #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.

🔬This is a nightly-only experimental API. (read_buf #78485)

Appends data to the cursor, advancing position within its buffer.

Panics

Panics if self.capacity() is less than buf.len().

Trait Implementations§

Formats the value using the given formatter. Read more
Write a buffer into this writer, returning how many bytes were written. Read more
Flush this output stream, ensuring that all intermediately buffered contents reach their destination. Read more
Like write, except that it writes from a slice of buffers. Read more
🔬This is a nightly-only experimental API. (can_vector #69941)
Determines if this Writer has an efficient write_vectored implementation. Read more
Attempts to write an entire buffer into this writer. Read more
🔬This is a nightly-only experimental API. (write_all_vectored #70436)
Attempts to write multiple buffers into this writer. Read more
Writes a formatted string into this writer, returning any error encountered. Read more
Creates a “by reference” adapter for this instance of Write. Read more

Auto Trait Implementations§

Blanket Implementations§

Gets the TypeId of self. Read more
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The type returned in the event of a conversion error.
Performs the conversion.
The type returned in the event of a conversion error.
Performs the conversion.