146 lines
4.2 KiB
Rust
146 lines
4.2 KiB
Rust
use bytes::{Buf, BufMut, Bytes, BytesMut};
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use futures::{stream::Stream, Async};
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use crate::ebml::{EbmlEventSource, FromEbml};
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use crate::error::WebmetroError;
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pub struct EbmlStreamingParser<S> {
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stream: S,
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buffer: BytesMut,
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buffer_size_limit: Option<usize>,
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borrowed: Bytes,
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}
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impl<S> EbmlStreamingParser<S> {
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/// add a "soft" buffer size limit; if the input buffer exceeds this size,
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/// error the stream instead of resuming. It's still possible for the buffer
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/// to exceed this size *after* a fill, so ensure input sizes are reasonable.
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pub fn with_soft_limit(mut self, limit: usize) -> Self {
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self.buffer_size_limit = Some(limit);
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self
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}
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}
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pub trait StreamEbml
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where
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Self: Sized + Stream,
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Self::Item: Buf,
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{
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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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buffer_size_limit: None,
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borrowed: Bytes::new(),
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}
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}
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}
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impl<I: Buf, S: Stream<Item = I, Error = WebmetroError>> StreamEbml for S {}
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impl<I: Buf, S: Stream<Item = I, Error = WebmetroError>> EbmlStreamingParser<S> {
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pub fn poll_event<'a, T: FromEbml<'a>>(
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&'a mut self,
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) -> Result<Async<Option<T>>, WebmetroError> {
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loop {
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match T::check_space(&self.buffer)? {
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None => {
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// need to refill buffer, below
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}
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Some(info) => {
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let mut bytes = self.buffer.split_to(info.element_len).freeze();
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bytes.advance(info.body_offset);
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self.borrowed = bytes;
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return Ok(Async::Ready(Some(T::decode(
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info.element_id,
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&self.borrowed,
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)?)));
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}
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}
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if let Some(limit) = self.buffer_size_limit {
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if limit <= self.buffer.len() {
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return Err(WebmetroError::ResourcesExceeded);
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}
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}
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match self.stream.poll()? {
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Async::Ready(Some(buf)) => {
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self.buffer.reserve(buf.remaining());
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self.buffer.put(buf);
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// ok can retry decoding now
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}
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other => return Ok(other.map(|_| None)),
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}
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}
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}
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}
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impl<I: Buf, S: Stream<Item = I, Error = WebmetroError>> EbmlEventSource
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for EbmlStreamingParser<S>
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{
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type Error = WebmetroError;
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fn poll_event<'a, T: FromEbml<'a>>(&'a mut self) -> Result<Async<Option<T>>, WebmetroError> {
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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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use bytes::IntoBuf;
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use futures::prelude::*;
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use futures::Async::*;
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use matches::assert_matches;
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use crate::stream_parser::*;
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use crate::tests::ENCODE_WEBM_TEST_FILE;
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use crate::webm::*;
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#[test]
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fn stream_webm_test() {
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let pieces = vec![
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&ENCODE_WEBM_TEST_FILE[0..20],
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&ENCODE_WEBM_TEST_FILE[20..40],
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&ENCODE_WEBM_TEST_FILE[40..],
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];
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let mut stream_parser = futures::stream::iter_ok(pieces.iter())
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.map(|bytes| bytes.into_buf())
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.parse_ebml();
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assert_matches!(
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stream_parser.poll_event(),
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Ok(Ready(Some(WebmElement::EbmlHead)))
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);
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assert_matches!(
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stream_parser.poll_event(),
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Ok(Ready(Some(WebmElement::Segment)))
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);
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assert_matches!(
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stream_parser.poll_event(),
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Ok(Ready(Some(WebmElement::Tracks(_))))
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);
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assert_matches!(
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stream_parser.poll_event(),
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Ok(Ready(Some(WebmElement::Cluster)))
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);
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assert_matches!(
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stream_parser.poll_event(),
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Ok(Ready(Some(WebmElement::Timecode(0))))
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);
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assert_matches!(
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stream_parser.poll_event(),
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Ok(Ready(Some(WebmElement::SimpleBlock(_))))
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);
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assert_matches!(
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stream_parser.poll_event(),
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Ok(Ready(Some(WebmElement::Cluster)))
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);
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assert_matches!(
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stream_parser.poll_event(),
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Ok(Ready(Some(WebmElement::Timecode(1000))))
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);
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}
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}
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