Struct byteio::Writer

pub struct Writer<W: WriteBytes>(_, _);

A convenience structure used for counting the number of bytes written.

This structure wraps an implementation of WriteBytes. It forwards write operations to the inner type while also maintaining a count of the number of bytes that pass through it.

When you have finished with it, you can return the original type via the into_inner method.

When compiled with the std feature this structure implements Write.

Examples

use byteio::{WriteBytes, WriteBytesExt, Writer};

fn main() -> byteio::Result<()> {
    let mut buf = [0; 7];

    {
        let mut writer = Writer::new(&mut buf[..]);

        writer.try_write_u8(1)?;
        writer.try_write_u16_be(2)?;
        writer.try_write_u32_be(3)?;

        assert_eq!(writer.num_bytes_written(), 7);

        let inner = writer.into_inner();
        assert!(inner.is_empty());
    }

    assert_eq!(buf, [1, 0, 2, 0, 0, 0, 3]);

    Ok(())
}

Methods

impl<W: WriteBytes> Writer<W>

pub fn new(writer: W) -> Self

Creates a new Writer by wrapping a WriteBytes implementor.

Examples

use byteio::Writer;

let mut buf = [0_u8; 2];
let mut writer = Writer::new(&mut buf[..]);

pub fn num_bytes_written(&self) -> usize

Retrieves the number of bytes that have been written by this Writer.

Examples

use byteio::{WriteBytes, Writer};

let mut buf = [0_u8; 2];
let mut writer = Writer::new(&mut buf[..]);
writer.write_exact(&[1]);
writer.write_exact(&[1]);

assert_eq!(writer.num_bytes_written(), 2);

pub fn into_inner(self) -> W

Consumes this Writer and returns the original WriteBytes implementor.

use byteio::{WriteBytes, Writer};

let mut buf = [0_u8; 2];
let mut writer = Writer::new(&mut buf[..]);
writer.write_exact(&[1]);
let inner = writer.into_inner();

assert_eq!(inner.len(), 1); // the writer consumed one byte from its view of the slice

Trait Implementations

impl<W: WriteBytes> WriteBytes for Writer<W>

fn write_exact(&mut self, buf: &[u8])

Forcibly attempts to write the exact slice into the buffer.

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

Attempts to write the exact slice into the buffer.

impl<W: PartialEq + WriteBytes> PartialEq<Writer<W>> for Writer<W>

fn eq(&self, other: &Writer<W>) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Writer<W>) -> bool

This method tests for !=.

impl<W: Eq + WriteBytes> Eq for Writer<W>

impl<W: Hash + WriteBytes> Hash for Writer<W>

fn hash<__HW: Hasher>(&self, state: &mut __HW)

Feeds this value into the given [Hasher].

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given [Hasher].

impl<W: Debug + WriteBytes> Debug for Writer<W>

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

Formats the value using the given formatter.

impl<W: WriteBytes> AsMut<[u8]> for Writer<W>

fn as_mut(&mut self) -> &mut [u8]

Performs the conversion.

impl<W: Clone + WriteBytes> Clone for Writer<W>

Important traits for Writer<W>

impl<W: WriteBytes> Write for Writer<W>

fn clone(&self) -> Writer<W>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<W: WriteBytes> Write for Writer<W>

fn write(&mut self, data: &[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_vectored(&mut self, bufs: &[IoSlice]) -> Result<usize, Error>

Like write, except that it writes from a slice of buffers.

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

Attempts to write an entire buffer into this writer.

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

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

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

Creates a "by reference" adaptor for this instance of Write.