Struct Cursor

pub struct Cursor<T> { /* private fields */ }

A Cursor wraps an in-memory buffer and provides it with a Seek implementation.

Cursors are used with in-memory buffers, anything implementing AsRef<[u8]>, to allow them to implement Read and/or Write, allowing these buffers to be used anywhere you might use a reader or writer that does actual I/O.

The standard library implements some I/O traits on various types which are commonly used as a buffer, like Cursor<Vec<u8>> and Cursor<&[u8]>.

Implementations

impl<T> Cursor<T>

pub fn new(inner: T) -> Cursor<T>

Creates a new cursor wrapping the provided underlying in-memory buffer.

Cursor initial position is 0 even if underlying buffer (e.g., Vec) is not empty. So writing to cursor starts with overwriting Vec content, not with appending to it.

pub fn into_inner(self) -> T

Consumes this cursor, returning the underlying value.

pub fn get_ref(&self) -> &T

Gets a reference to the underlying value in this cursor.

pub fn get_mut(&mut self) -> &mut T

Gets a mutable reference to the underlying value in this cursor.

Care should be taken to avoid modifying the internal I/O state of the underlying value as it may corrupt this cursor’s position.

pub fn position(&self) -> u64

Returns the current position of this cursor.

pub fn set_position(&mut self, pos: u64)

Sets the position of this cursor.

Trait Implementations

impl<T> BufRead for Cursor<T>

where T: AsRef<[u8]>,

fn fill_buf(&mut self) -> Result<&[u8]>

Returns the contents of the internal buffer, filling it with more data from the inner reader if it is empty.

fn consume(&mut self, amt: usize)

Tells this buffer that amt bytes have been consumed from the buffer, so they should no longer be returned in calls to read.

fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> Result<usize>

Available on crate feature alloc only.

Read all bytes into buf until the delimiter byte or EOF is reached.

fn read_line(&mut self, buf: &mut String) -> Result<usize>

Available on crate feature alloc only.

Read all bytes until a newline (the 0xA byte) is reached, and append them to the provided buffer.

fn split(self, byte: u8) -> Split<Self>

where Self: Sized,

Available on crate feature alloc only.

Returns an iterator over the contents of this reader split on the byte byte.

fn lines(self) -> Lines<Self>

where Self: Sized,

Available on crate feature alloc only.

Returns an iterator over the lines of this reader.

impl<T: Clone> Clone for Cursor<T>

fn clone(&self) -> Cursor<T>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug> Debug for Cursor<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T: Default> Default for Cursor<T>

fn default() -> Cursor<T>

Returns the “default value” for a type.

impl<T> Read for Cursor<T>

where T: AsRef<[u8]>,

fn read(&mut self, buf: &mut [u8]) -> Result<usize>

Pull some bytes from this source into the specified buffer, returning how many bytes were read.

fn read_exact(&mut self, buf: &mut [u8]) -> Result<()>

Read the exact number of bytes required to fill buf.

unsafe fn initializer(&self) -> Initializer

Determines if this Reader can work with buffers of uninitialized memory.

fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize>

Available on crate feature alloc only.

Read all bytes until EOF in this source, placing them into buf.

fn read_to_string(&mut self, buf: &mut String) -> Result<usize>

Available on crate feature alloc only.

Read all bytes until EOF in this source, appending them to buf.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adaptor for this instance of Read.

fn bytes(self) -> Bytes<Self>

where Self: Sized,

Transforms this Read instance to an Iterator over its bytes.

fn chain<R: Read>(self, next: R) -> Chain<Self, R>

where Self: Sized,

Creates an adaptor which will chain this stream with another.

fn take(self, limit: u64) -> Take<Self>

where Self: Sized,

Creates an adaptor which will read at most limit bytes from it.

impl<T> Seek for Cursor<T>

where T: AsRef<[u8]>,

fn seek(&mut self, style: SeekFrom) -> Result<u64>

Seek to an offset, in bytes, in a stream.

fn stream_len(&mut self) -> Result<u64>

Returns the length of this stream (in bytes).

fn stream_position(&mut self) -> Result<u64>

Returns the current seek position from the start of the stream.

impl Write for Cursor<&mut [u8]>

fn write(&mut self, buf: &[u8]) -> Result<usize>

Write a buffer into this writer, returning how many bytes were written.

fn flush(&mut self) -> Result<()>

Flush this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_all(&mut self, buf: &[u8]) -> Result<()>

Attempts to write an entire buffer into this writer.

fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result<()>

Writes a formatted string into this writer, returning any error encountered.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adaptor for this instance of Write.

impl Write for Cursor<&mut Vec<u8>>

Available on crate feature alloc only.

fn write(&mut self, buf: &[u8]) -> Result<usize>

Write a buffer into this writer, returning how many bytes were written.

fn flush(&mut self) -> Result<()>

Flush this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_all(&mut self, buf: &[u8]) -> Result<()>

Attempts to write an entire buffer into this writer.

fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result<()>

Writes a formatted string into this writer, returning any error encountered.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adaptor for this instance of Write.

impl Write for Cursor<Box<[u8]>>

Available on crate feature alloc only.

fn write(&mut self, buf: &[u8]) -> Result<usize>

Write a buffer into this writer, returning how many bytes were written.

fn flush(&mut self) -> Result<()>

Flush this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_all(&mut self, buf: &[u8]) -> Result<()>

Attempts to write an entire buffer into this writer.

fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result<()>

Writes a formatted string into this writer, returning any error encountered.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adaptor for this instance of Write.

impl Write for Cursor<Vec<u8>>

Available on crate feature alloc only.

fn write(&mut self, buf: &[u8]) -> Result<usize>

Write a buffer into this writer, returning how many bytes were written.

fn flush(&mut self) -> Result<()>

Flush this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_all(&mut self, buf: &[u8]) -> Result<()>

Attempts to write an entire buffer into this writer.

fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result<()>

Writes a formatted string into this writer, returning any error encountered.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adaptor for this instance of Write.