Struct StreamingDecoder 

pub struct StreamingDecoder<READ: Read, DEC: BorrowMut<FrameDecoder>> {
    pub decoder: DEC,
    /* private fields */
}

High level Zstandard frame decoder that can be used to decompress a given Zstandard frame.

This decoder implements io::Read, so you can interact with it by calling io::Read::read_to_end / io::Read::read_exact or passing this to another library / module as a source for the decoded content

If you need more control over how decompression takes place, you can use the lower level FrameDecoder, which allows for greater control over how decompression takes place but the implementor must call FrameDecoder::decode_blocks repeatedly to decode the entire frame.

Caveat

Plain read / read_exact operate on the single frame this decoder was initialised with: they do not advance into following frames. read_to_end, by contrast, is specialised to consume a finite source to EOF, decoding concatenated frames and skipping skippable frames along the way.

To recover the bytes that follow one frame WITHOUT consuming the rest of the source, recreate the decoder manually and handle crate::decoding::errors::ReadFrameHeaderError::SkipFrame errors by skipping forward the length amount of bytes, see https://github.com/KillingSpark/zstd-rs/issues/57

// `File` is std-only; `read_to_end` itself is available under no_std too.
#[cfg(feature = "std")]
{
    use std::fs::File;
    use std::io::Read;
    use structured_zstd::decoding::StreamingDecoder;

    // Read a Zstandard archive from the filesystem then decompress it into a vec.
    let mut f: File = todo!("Read a .zstd archive from somewhere");
    let mut decoder = StreamingDecoder::new(f).unwrap();
    let mut result = Vec::new();
    Read::read_to_end(&mut decoder, &mut result).unwrap();
}

Fields

decoder: DEC

Implementations

impl<READ: Read, DEC: BorrowMut<FrameDecoder>> StreamingDecoder<READ, DEC>

pub fn new_with_decoder( source: READ, decoder: DEC, ) -> Result<StreamingDecoder<READ, DEC>, FrameDecoderError>

impl<READ: Read> StreamingDecoder<READ, FrameDecoder>

pub fn new( source: READ, ) -> Result<StreamingDecoder<READ, FrameDecoder>, FrameDecoderError>

pub fn new_with_dictionary_handle( source: READ, dict: &DictionaryHandle, ) -> Result<StreamingDecoder<READ, FrameDecoder>, FrameDecoderError>

Create a streaming decoder using a pre-parsed dictionary handle.

Warning

This constructor initializes the underlying FrameDecoder with dict, even if a frame header omits the optional dictionary ID. Callers must only use it when they already know the stream was encoded with this dictionary; otherwise decoded output can be silently corrupted.

pub fn new_with_dictionary_bytes( source: READ, raw_dictionary: &[u8], ) -> Result<StreamingDecoder<READ, FrameDecoder>, FrameDecoderError>

Create a streaming decoder using a serialized dictionary blob.

Warning

This API forwards to StreamingDecoder::new_with_dictionary_handle and therefore applies the decoded dictionary to frames whose headers may omit the optional dictionary ID. Only use it when the stream is known to be encoded with that dictionary.

impl<READ: Read, DEC: BorrowMut<FrameDecoder>> StreamingDecoder<READ, DEC>

pub fn get_ref(&self) -> &READ

Gets a reference to the underlying reader.

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

Gets a mutable reference to the underlying reader.

It is inadvisable to directly read from the underlying reader.

pub fn into_inner(self) -> READ

where READ: Sized,

Destructures this object into the inner reader.

pub fn into_parts(self) -> (READ, DEC)

where READ: Sized,

Destructures this object into both the inner reader and FrameDecoder.

pub fn into_frame_decoder(self) -> DEC

Destructures this object into the inner FrameDecoder.

Trait Implementations

impl<READ: Read, DEC: BorrowMut<FrameDecoder>> Read for StreamingDecoder<READ, DEC>

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

Decode-in-place fast path for whole-frame consumption. Instead of the generic read loop (decode block -> RingBuffer -> copy into the caller buffer), buffer the (compressed, hence small) source and decode STRAIGHT into output’s spare capacity via the single-copy direct path, pre-sized from the frame’s declared content size. Only taken when the decoder is at a frame boundary (nothing partially decoded / undrained); otherwise it falls back to the generic grow-and-read loop so a caller that mixed read with read_to_end still gets correct output.

Per the Read::read_to_end contract this consumes the source to EOF: if the stream holds several concatenated frames they are ALL decoded (and skippable frames skipped). To recover bytes that follow a single frame, use read plus the SkipFrame recreate-the-decoder pattern instead.

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

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_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<'_, u8>) -> 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<'_, u8>, ) -> 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.

fn read_le<T>(&mut self) -> Result<T, Error>

where T: FromEndianBytes, Self: Sized,

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

Read and return a type (e.g. an integer) in little-endian order.

fn read_be<T>(&mut self) -> Result<T, Error>

where T: FromEndianBytes, Self: Sized,

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

Read and return a type (e.g. an integer) in big-endian order.