100 lines
2.9 KiB
Rust
100 lines
2.9 KiB
Rust
use std::{
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error::Error,
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fmt::{Display, Formatter, Result as FmtResult}
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};
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use bytes::BytesMut;
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use bytes::BufMut;
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use futures::Async;
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use futures::stream::Stream;
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use ebml::EbmlError;
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use ebml::EbmlEventSource;
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use ebml::FromEbml;
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#[derive(Debug)]
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pub enum ParsingError<E> {
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EbmlError(EbmlError),
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OtherError(E)
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}
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impl<E: Display + Error> Display for ParsingError<E> {
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fn fmt(&self, f: &mut Formatter) -> FmtResult {
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write!(f, "Parsing error: {}", self.description())
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}
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}
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impl<E: Error> Error for ParsingError<E> {
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fn description(&self) -> &str {
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match self {
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&ParsingError::EbmlError(ref err) => err.description(),
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&ParsingError::OtherError(ref err) => err.description()
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}
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}
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}
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pub struct EbmlStreamingParser<S> {
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stream: S,
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buffer: BytesMut,
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last_read: usize
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}
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pub trait StreamEbml where Self: Sized + Stream, Self::Item: AsRef<[u8]> {
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fn parse_ebml(self) -> EbmlStreamingParser<Self> {
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EbmlStreamingParser {
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stream: self,
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buffer: BytesMut::new(),
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last_read: 0
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}
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}
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}
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impl<I: AsRef<[u8]>, S: Stream<Item = I>> StreamEbml for S {}
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impl<I: AsRef<[u8]>, S: Stream<Item = I>> EbmlStreamingParser<S> {
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pub fn poll_event<'a, T: FromEbml<'a>>(&'a mut self) -> Result<Async<Option<T>>, ParsingError<S::Error>> {
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// release buffer from previous event
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self.buffer.advance(self.last_read);
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self.last_read = 0;
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loop {
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match T::check_space(&self.buffer) {
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Ok(None) => {
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// need to refill buffer, below
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},
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other => return other.map_err(ParsingError::EbmlError).and_then(move |_| {
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match T::decode_element(&self.buffer) {
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Err(err) => Err(ParsingError::EbmlError(err)),
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Ok(None) => panic!("Buffer was supposed to have enough data to parse element, somehow did not."),
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Ok(Some((element, element_size))) => {
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self.last_read = element_size;
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Ok(Async::Ready(Some(element)))
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}
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}
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})
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}
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match self.stream.poll().map_err(ParsingError::OtherError) {
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Ok(Async::Ready(Some(chunk))) => {
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self.buffer.reserve(chunk.as_ref().len());
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self.buffer.put_slice(chunk.as_ref());
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// ok can retry decoding now
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},
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other => return other.map(|async| async.map(|_| None))
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}
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}
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}
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}
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impl<I: AsRef<[u8]>, S: Stream<Item = I>> EbmlEventSource for EbmlStreamingParser<S> {
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type Error = ParsingError<S::Error>;
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fn poll_event<'a, T: FromEbml<'a>>(&'a mut self) -> Result<Async<Option<T>>, Self::Error> {
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return EbmlStreamingParser::poll_event(self);
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}
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}
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#[cfg(test)]
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mod tests {
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//#[test]
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}
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