Give stream_parser an async next() method, making async_parser no longer interesting.

src/async_parser.rs

@@ -1,108 +0,0 @@
-use bytes::{Bytes, BytesMut};
-use std::future::Future;
-
-use crate::ebml::FromEbml;
-use crate::error::WebmetroError;
-
-#[derive(Default)]
-pub struct EbmlParser {
-    buffer: BytesMut,
-    buffer_size_limit: Option<usize>,
-    borrowed: Bytes
-}
-
-impl EbmlParser {
-    /// add a "soft" buffer size limit; if the input buffer exceeds this size,
-    /// error the stream instead of resuming. It's still possible for the buffer
-    /// to exceed this size *after* a fill, so ensure input sizes are reasonable.
-    pub fn with_soft_limit(mut self, limit: usize) -> Self {
-        self.buffer_size_limit = Some(limit);
-        self
-    }
-
-    pub fn feed(&mut self, bytes: impl AsRef<[u8]>) {
-        self.buffer.extend_from_slice(bytes.as_ref())
-    }
-
-    pub fn next_element<'a, T: FromEbml<'a>>(&'a mut self) -> Result<Option<T>, WebmetroError> {
-        Ok(match T::check_space(&self.buffer)? {
-            None => None,
-            Some(info) => {
-                let mut bytes = self.buffer.split_to(info.element_len).freeze();
-                bytes.advance(info.body_offset);
-                self.borrowed = bytes;
-                Some(T::decode(info.element_id, &self.borrowed)?)
-            }
-        })
-    }
-
-    pub async fn next_element_with_feeder<
-        'a,
-        T: FromEbml<'a>,
-        F: FnMut() -> Fut,
-        Fut: Future<Output = Result<Bytes, WebmetroError>>,
-    >(
-        &'a mut self,
-        mut feeder: F,
-    ) -> Result<Option<T>, WebmetroError> {
-        loop {
-            if let Some(_) = T::check_space(&self.buffer)? {
-                return self.next_element();
-            }
-
-            if let Some(limit) = self.buffer_size_limit {
-                if limit <= self.buffer.len() {
-                    // hit our buffer limit and still nothing parsed
-                    return Err(WebmetroError::ResourcesExceeded);
-                }
-            }
-
-            self.buffer.extend(feeder().await?);
-        }
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use matches::assert_matches;
-
-    use crate::async_parser::*;
-    use crate::tests::ENCODE_WEBM_TEST_FILE;
-    use crate::webm::*;
-
-    #[test]
-    fn async_webm_test() {
-        let pieces = vec![
-            &ENCODE_WEBM_TEST_FILE[0..20],
-            &ENCODE_WEBM_TEST_FILE[20..40],
-            &ENCODE_WEBM_TEST_FILE[40..],
-        ];
-
-        let mut piece_iter = pieces.iter();
-
-        let result: Result<_, WebmetroError> = futures3::executor::block_on(async {
-            let mut next = || {
-                let result = if let Some(bytes) = piece_iter.next() {
-                    Ok(Bytes::from(*bytes))
-                } else {
-                    Err("End of input".into())
-                };
-                async { result }
-            };
-
-            let mut parser = EbmlParser::default();
-
-            assert_matches!(parser.next_element_with_feeder(&mut next).await?, Some(WebmElement::EbmlHead));
-            assert_matches!(parser.next_element_with_feeder(&mut next).await?, Some(WebmElement::Segment));
-            assert_matches!(parser.next_element_with_feeder(&mut next).await?, Some(WebmElement::Tracks(_)));
-            assert_matches!(parser.next_element_with_feeder(&mut next).await?, Some(WebmElement::Cluster));
-            assert_matches!(parser.next_element_with_feeder(&mut next).await?, Some(WebmElement::Timecode(0)));
-            assert_matches!(parser.next_element_with_feeder(&mut next).await?, Some(WebmElement::SimpleBlock(_)));
-            assert_matches!(parser.next_element_with_feeder(&mut next).await?, Some(WebmElement::Cluster));
-            assert_matches!(parser.next_element_with_feeder(&mut next).await?, Some(WebmElement::Timecode(1000)));
-
-            Ok(())
-        });
-        result.unwrap();
-    }
-}

src/stream_parser.rs

@@ -80,15 +80,42 @@ impl<I: Buf, S: Stream<Item = Result<I, WebmetroError>> + Unpin> EbmlStreamingPa
     }
 }
 
+impl<I: Buf, S: Stream<Item = Result<I, WebmetroError>> + Unpin> EbmlStreamingParser<S> {
+    pub async fn next<'a, T: FromEbml<'a>>(&'a mut self) -> Result<Option<T>, WebmetroError> {
+        loop {
+            if let Some(info) = T::check_space(&self.buffer)? {
+                let mut bytes = self.buffer.split_to(info.element_len).freeze();
+                bytes.advance(info.body_offset);
+                self.borrowed = bytes;
+                return Ok(Some(T::decode(info.element_id, &self.borrowed)?));
+            }
+
+            if let Some(limit) = self.buffer_size_limit {
+                if limit <= self.buffer.len() {
+                    // hit our buffer limit and still nothing parsed
+                    return Err(WebmetroError::ResourcesExceeded);
+                }
+            }
+
+            match self.stream.next().await.transpose()? {
+                Some(refill) => {
+                    self.buffer.reserve(refill.remaining());
+                    self.buffer.put(refill);
+                }
+                None => {
+                    // Nothing left, we're done
+                    return Ok(None);
+                }
+            }
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use bytes::IntoBuf;
     use futures::Async::*;
-    use futures3::{
+    use futures3::{future::poll_fn, stream::StreamExt, FutureExt};
-        future::poll_fn,
-        stream::StreamExt,
-        FutureExt,
-    };
     use matches::assert_matches;
 
     use crate::stream_parser::*;
@@ -144,6 +171,35 @@ mod tests {
             std::task::Poll::Ready(())
         })
         .now_or_never()
-        .expect("Test succeeded without blocking");
+        .expect("Test tried to block on I/O");
+    }
+
+    #[test]
+    fn async_webm_test() {
+        let pieces = vec![
+            &ENCODE_WEBM_TEST_FILE[0..20],
+            &ENCODE_WEBM_TEST_FILE[20..40],
+            &ENCODE_WEBM_TEST_FILE[40..],
+        ];
+
+        async {
+            let mut parser = futures3::stream::iter(pieces.iter())
+                .map(|bytes| Ok(bytes.into_buf()))
+                .parse_ebml();
+
+            assert_matches!(parser.next().await?, Some(WebmElement::EbmlHead));
+            assert_matches!(parser.next().await?, Some(WebmElement::Segment));
+            assert_matches!(parser.next().await?, Some(WebmElement::Tracks(_)));
+            assert_matches!(parser.next().await?, Some(WebmElement::Cluster));
+            assert_matches!(parser.next().await?, Some(WebmElement::Timecode(0)));
+            assert_matches!(parser.next().await?, Some(WebmElement::SimpleBlock(_)));
+            assert_matches!(parser.next().await?, Some(WebmElement::Cluster));
+            assert_matches!(parser.next().await?, Some(WebmElement::Timecode(1000)));
+
+            Result::<(), WebmetroError>::Ok(())
+        }
+        .now_or_never()
+        .expect("Test tried to block on I/O")
+        .expect("Parse failed");
     }
 }