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// use log::{debug, error};
use std::io::{Error as IoError, Read};
#[cfg(feature = "flate2")]
use flate2::read::GzDecoder;
// use log::warn;
use crate::prelude::{ClosedSourceElement, Error, Message, StreamElement};
/// Abstraction for Plain or Compressed [R]
enum Reader<R: Read> {
Plain(R),
#[cfg(feature = "flate2")]
Compressed(GzDecoder<R>),
}
impl<R: Read> From<R> for Reader<R> {
fn from(r: R) -> Reader<R> {
Self::Plain(r)
}
}
#[cfg(feature = "flate2")]
#[cfg_attr(docsrs, doc(cfg(feature = "flate2")))]
impl<R: Read> From<GzDecoder<R>> for Reader<R> {
fn from(r: GzDecoder<R>) -> Reader<R> {
Self::Compressed(r)
}
}
impl<R: Read> Read for Reader<R> {
fn read(&mut self, buf: &mut [u8]) -> Result<usize, IoError> {
match self {
Self::Plain(r) => r.read(buf),
#[cfg(feature = "flate2")]
Self::Compressed(r) => r.read(buf),
}
}
}
/// BINEX Stream Decoder. Use this structure to decode a serie
/// of [StreamElement]s streamed over any [Read]able interface.
pub struct Decoder<'a, R: Read> {
/// Write pointer
wr_ptr: usize,
/// Read pointer
rd_ptr: usize,
/// Reached EOS
eos: bool,
/// Internal buffer. Buffer is sized to fully contain
/// the "worst case" open source [Message].
buf: [u8; 4096],
/// [R]
reader: Reader<R>,
/// Reference to past [ClosedSourceElement] (if any)
past_element: Option<ClosedSourceElement<'a>>,
}
impl<'a, R: Read> Decoder<'a, R> {
/// Creates a new BINEX [Decoder] from [R] readable interface,
/// ready to parse incoming bytes. We only host gzip compressed
/// BINEX files, refer to [Decoder::new_gzip] for an example.
pub fn new(reader: R) -> Self {
Self {
eos: false,
rd_ptr: 0,
wr_ptr: 0,
buf: [0; 4096],
past_element: None,
reader: reader.into(),
}
}
#[cfg(feature = "flate2")]
#[cfg_attr(docsrs, doc(cfg(feature = "flate2")))]
/// Creates a new Compressed BINEX stream [Decoder] from [R] readable
/// interface, that must stream Gzip encoded bytes.
/// ```
/// use std::fs::File;
/// use flate2::read::GzDecoder;
/// use binex::prelude::{Decoder, Error};
///
/// // Create the Decoder:
/// // * works from our local source
/// // * needs to be mutable due to iterating process
/// let mut fd = File::open("data/BIN/mfle20200105.bnx.gz")
/// .unwrap();
///
/// let mut decoder = Decoder::new(GzDecoder::new(fd));
///
/// // Consume data stream
/// loop {
/// match decoder.next() {
/// Some(Ok(msg)) => {
/// // do something
/// },
/// Some(Err(e)) => match e {
/// Error::IoError => {
/// // any I/O error should be handled
/// // and user should react accordingly,
/// break;
/// },
/// Error::ReversedStream => {
/// // this library is currently limited:
/// // - reversed streams are not supported yet
/// // - little endian streams are not supported yet
/// },
/// _ => {},
/// },
/// None => {
/// // End of stream!
/// break;
/// },
/// }
/// }
/// ```
pub fn new_gzip(reader: R) -> Self {
Self {
eos: false,
rd_ptr: 0,
wr_ptr: 0,
buf: [0; 4096],
past_element: None,
reader: GzDecoder::new(reader).into(),
}
}
}
impl<'a, R: Read> Iterator for Decoder<'a, R> {
type Item = Result<StreamElement<'a>, Error>;
/// Parse next [StreamElement] contained in this BINEX stream.
fn next(&mut self) -> Option<Self::Item> {
// always try to fill internal buffer
let size = self.reader.read(&mut self.buf[self.wr_ptr..]).ok()?;
self.wr_ptr += size;
//println!("wr_ptr={}", self.wr_ptr);
if size == 0 {
self.eos = true;
}
// try to consume one message
match Message::decode(&self.buf[self.rd_ptr..]) {
Ok(msg) => {
// one message fully decoded
// - increment pointer
// - expose to user
self.rd_ptr += msg.encoding_size();
// terminates possible [ClosedSourceElement] serie
self.past_element = None;
Some(Ok(msg.into()))
},
Err(e) => {
match e {
Error::NoSyncByte => {
// buffer does not even contain the sync byte:
// we can safely discard everything
self.wr_ptr = 0;
self.rd_ptr = 0;
if self.eos {
// consumed everything and EOS has been reached
return None;
}
},
Error::NonSupportedMesssage(mlen) => {
self.rd_ptr += mlen;
if self.rd_ptr > 4096 {
self.rd_ptr = 0;
self.wr_ptr = 0;
}
if self.eos {
// consumed everything and EOS has been reached
return None;
}
},
Error::IncompleteMessage(mlen) => {
// decoded partial valid frame
if self.rd_ptr + mlen > 4096 {
// frame would not fit in buffer:
// abort: we do not support that scenario.
// This should never happen anyway: internal buffer should be sized correctly.
self.buf = [0; 4096];
self.wr_ptr = 0;
self.rd_ptr = 0;
return Some(Err(Error::TooLargeInternalLimitation));
} else {
// preserved content (shift left)
// and permit the refill that will conclude this message
self.buf.copy_within(self.rd_ptr.., 0);
self.wr_ptr -= self.rd_ptr;
self.rd_ptr = 0;
return Some(Err(Error::IncompleteMessage(mlen)));
}
},
Error::ClosedSourceMessage(closed_source) => {
// determine whether
// - this element is self sustained (ie., fully described by this meta)
// - the followup of previous elements
// - or the last element of a serie
if self.rd_ptr + closed_source.size < 4096 {
// content is fully wrapped in buffer: expose as is
// self.past_element = Some(ClosedSourceElement {
// provider: meta.provider,
// size: meta.mlen,
// total: meta.mlen,
// raw: self.buf[self.rd_ptr..self.rd_ptr +meta.mlen],
// });
} else {
// content is not fully wrapped up here;
// initiate or continue a serie of undisclosed element
}
return Some(Err(Error::IncompleteMessage(closed_source.size)));
},
Error::UnknownMessage => {
// panic!("unknown message\nrd_ptr={}\nbuf={:?}", self.rd_ptr, &self.buf[self.rd_ptr-1..self.rd_ptr+4]);
self.rd_ptr += 1;
},
_ => {
// bad content that does not look like valid BINEX.
// This is very inefficient. If returned error would increment
// the internal pointer, we could directly move on to next interesting bytes.
self.rd_ptr += 1;
},
}
Some(Err(e))
},
}
}
}