Struct DecodingReader 

pub struct DecodingReader<R> { /* private fields */ }

Available on crate feature encoding only.

A reader wrapper that decodes a byte stream from any encoding into UTF-8.

This reader wraps a BufRead source and uses encoding_rs::Decoder to transcode the input into valid UTF-8. On first access, it detects the encoding from BOM or XML declaration byte patterns and configures the appropriate decoder.

For UTF-8 input, this acts as a validating passthrough. For UTF-16 or other encodings, the bytes are transcoded into UTF-8 in an internal buffer.

Examples

use std::io::Read;
use quick_xml::encoding::DecodingReader;

// UTF-8 input passes through:
let data = b"Hello, World!";
let mut reader = DecodingReader::new(&data[..]);
let mut buf = Vec::new();
reader.read_to_end(&mut buf).unwrap();
assert_eq!(buf, data);

The example below shows how you can read documents using DecodingReader:

use quick_xml::encoding::DecodingReader;
use quick_xml::events::Event;
use quick_xml::reader::Reader;

let xml = to_utf16le_with_bom("<?xml encoding='UTF-16'?><element/>");
let mut decoder = DecodingReader::new(xml.as_ref());
let mut reader = Reader::from_reader(decoder);

let mut buf = Vec::new();
loop {
    buf.clear();
    match reader.read_event_into(&mut buf).unwrap() {
        Event::Decl(e) => {
            // If XML declaration contains unknown encoding name, None is returned
            match e.encoder() {
                Some(encoding) => reader.get_mut().set_encoding(encoding),
                None => panic!("Unsupported encoding {:?}", e.encoding()),
            }
        }
        Event::Eof => break,
        _ => {}
    }
}

Implementations

impl<R> DecodingReader<R>

pub fn new(inner: R) -> Self

Creates a new decoding reader.

The encoding is auto-detected from BOM or XML declaration patterns on first access. Defaults to UTF-8 if no pattern is recognized.

pub const fn get_ref(&self) -> &R

Returns a reference to the underlying reader

pub const fn get_mut(&mut self) -> &mut R

Returns a mutable reference to the underlying reader

pub fn into_inner(self) -> R

Consumes this reader and returns the underlying reader

pub fn encoding(&self) -> &'static Encoding

Returns the encoding currently used by the decoder.

Before the first read, this is always UTF-8. After encoding detection it reflects the detected (or overridden) encoding.

pub fn set_encoding(&mut self, encoding: &'static Encoding)

Replaces the decoder with one for the given encoding. The encoding must be ASCII-compatible (the parser cannot read the declaration otherwise).

Panics

Panics if the prefix buffer has already been drained. Must be called before the prefix is exhausted — in practice, right after parsing the XML declaration.

Trait Implementations

impl<R: BufRead> BufRead for DecodingReader<R>

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<R: Debug> Debug for DecodingReader<R>

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

Formats the value using the given formatter.

impl<R: BufRead> Read for DecodingReader<R>

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” adapter 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.

fn read_array<const N: usize>(&mut self) -> Result<[u8; N], Error>

where Self: Sized,

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

Read and return a fixed array of bytes from this source.