109 lines
3.7 KiB
Rust
109 lines
3.7 KiB
Rust
use bytes::{Bytes, BytesMut};
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use std::future::Future;
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use crate::ebml::FromEbml;
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use crate::error::WebmetroError;
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#[derive(Default)]
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pub struct EbmlParser {
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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 EbmlParser {
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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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pub fn feed(&mut self, bytes: impl AsRef<[u8]>) {
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self.buffer.extend_from_slice(bytes.as_ref())
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}
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pub fn next_element<'a, T: FromEbml<'a>>(&'a mut self) -> Result<Option<T>, WebmetroError> {
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Ok(match T::check_space(&self.buffer)? {
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None => None,
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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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Some(T::decode(info.element_id, &self.borrowed)?)
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}
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})
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}
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pub async fn next_element_with_feeder<
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'a,
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T: FromEbml<'a>,
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F: FnMut() -> Fut,
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Fut: Future<Output = Result<Bytes, WebmetroError>>,
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>(
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&'a mut self,
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mut feeder: F,
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) -> Result<Option<T>, WebmetroError> {
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loop {
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if let Some(_) = T::check_space(&self.buffer)? {
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return self.next_element();
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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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// hit our buffer limit and still nothing parsed
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return Err(WebmetroError::ResourcesExceeded);
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}
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}
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self.buffer.extend(feeder().await?);
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}
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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 matches::assert_matches;
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use crate::async_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 async_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 piece_iter = pieces.iter();
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let result: Result<_, WebmetroError> = futures3::executor::block_on(async {
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let mut next = || {
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let result = if let Some(bytes) = piece_iter.next() {
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Ok(Bytes::from(*bytes))
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} else {
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Err("End of input".into())
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};
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async { result }
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};
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let mut parser = EbmlParser::default();
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assert_matches!(parser.next_element_with_feeder(&mut next).await?, Some(WebmElement::EbmlHead));
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assert_matches!(parser.next_element_with_feeder(&mut next).await?, Some(WebmElement::Segment));
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assert_matches!(parser.next_element_with_feeder(&mut next).await?, Some(WebmElement::Tracks(_)));
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assert_matches!(parser.next_element_with_feeder(&mut next).await?, Some(WebmElement::Cluster));
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assert_matches!(parser.next_element_with_feeder(&mut next).await?, Some(WebmElement::Timecode(0)));
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assert_matches!(parser.next_element_with_feeder(&mut next).await?, Some(WebmElement::SimpleBlock(_)));
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assert_matches!(parser.next_element_with_feeder(&mut next).await?, Some(WebmElement::Cluster));
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assert_matches!(parser.next_element_with_feeder(&mut next).await?, Some(WebmElement::Timecode(1000)));
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Ok(())
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});
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result.unwrap();
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}
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}
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