Struct Reader

pub struct Reader<'a> { /* private fields */ }

A Reader implements the crate::io::Reader, crate::io::ReaderAt, crate::io::WriterTo, crate::io::Seeker, crate::io::ByteScanner, and io.RuneScanner interfaces by reading from a u8 slice. Unlike a Buffer, a Reader is read-only and supports seeking. The zero value for Reader operates like a Reader of an empty slice.

Implementations

impl<'a> Reader<'a>

pub fn new(b: &'a [u8]) -> Self

new returns a new Reader reading from b.

Examples found in repository

examples/zlib-reader.rs (line 11)

fn main() {
    let buff: &[u8] = &[
        120, 156, 202, 72, 205, 201, 201, 215, 81, 40, 207, 47, 202, 73, 225, 2, 4, 0, 0, 255, 255,
        33, 231, 4, 147,
    ];
    let mut b = bytes::Reader::new(buff);
    let mut r = zlib::Reader::new(&mut b).unwrap();

    // reading using Reader::read
    // loop {
    //     let mut buf = [0; 10];
    //     let res = r.read(&mut buf);
    //     if res.is_err() {
    //         break;
    //     }
    //     let n = res.unwrap();
    //     if n == 0 {
    //         break;
    //     }
    // }

    // reading using std::io::Read::read_to_string
    let mut output = String::new();
    r.read_to_string(&mut output).unwrap();
    println!("{}", output);

    r.close().unwrap();
}

examples/png-decode.rs (line 18)

fn example_decode() {
    let image_data = base64::get_std_encoding().decode_to_vec(GOPHER).unwrap();
    let mut r = bytes::Reader::new(&image_data);

    // This example uses png.Decode which can only decode PNG images.
    // Consider using the general image.Decode as it can sniff and decode any registered image format.
    let img = png::decode(&mut r).unwrap();

    let levels = [" ", "░", "▒", "▓", "█"];

    for y in img.bounds().min.y..img.bounds().max.y {
        for x in img.bounds().min.x..img.bounds().max.x {
            let c = color::Gray::new_from(&img.at(x, y));
            let mut level = c.y / 51; // 51 * 5 = 255
            if level == 5 {
                level -= 1;
            }
            print!("{}", levels[level as usize]);
        }
        println!();
    }
}

pub fn len(&self) -> usize

len returns the number of bytes of the unread portion of the slice.

pub fn is_empty(&self) -> bool

pub fn size(&mut self) -> usize

size returns the original length of the underlying u8 slice. size is the number of bytes available for reading via read_at. The result is unaffected by any method calls except reset.

impl Reader<'_>

pub fn read_at(&mut self, b: &mut [u8], off: u64) -> Result<usize>

read_at implements the io.ReaderAt interface.

impl<'a> Reader<'a>

pub fn unread_byte(&mut self) -> Result<()>

unread_byte complements read_byte in implementing the io.ByteScanner interface.

pub fn seek(&mut self, offset: i64, whence: Seek) -> Result<u64>

seek implements the io.Seeker interface.

pub fn write_to(&mut self, w: &mut dyn Write) -> Result<usize>

write_to implements the io.WriterTo interface.

pub fn reset(&mut self, b: &'a [u8])

reset resets the Reader to be reading from b.

Trait Implementations

impl BufRead for Reader<'_>

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

Returns the contents of the internal buffer, filling it with more data, via Read methods, if empty.

fn consume(&mut self, amt: usize)

Marks the given amount of additional bytes from the internal buffer as having been read. Subsequent calls to read only return bytes that have not been marked as read.

fn has_data_left(&mut self) -> Result<bool, Error>

🔬This is a nightly-only experimental API. (buf_read_has_data_left)

Checks if there is any data left to be read.

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

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

fn skip_until(&mut self, byte: u8) -> Result<usize, Error>

Skips all bytes until the delimiter byte or EOF is reached.

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

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

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

where Self: Sized,

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

fn lines(self) -> Lines<Self>

where Self: Sized,

Returns an iterator over the lines of this reader.

impl ByteReader for Reader<'_>

fn read_byte(&mut self) -> Result<u8>

read_byte implements the io.ByteReader interface.

impl Read for Reader<'_>

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_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize, Error>

Like read, except that it reads into a slice of buffers.

fn is_read_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector)

Determines if this Reader has an efficient read_vectored implementation.

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

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

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

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

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

Reads the exact number of bytes required to fill buf.

fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> Result<(), Error>

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

Pull some bytes from this source into the specified buffer.

fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<(), Error>

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

Reads the exact number of bytes required to fill cursor.

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

where R: Read, Self: Sized,

Creates an adapter which will chain this stream with another.

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

where Self: Sized,

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