Struct FramedReader 

pub struct FramedReader<F: FnMut() -> u32> { /* private fields */ }

Streaming counterpart to read_framed_bytes_with: a FramedRead source that pulls framed words on demand instead of first materializing the whole payload into a Vec<u8>. Only a single word is buffered at a time, so it holds O(1) memory regardless of payload size — letting a decoder run at ~1x peak memory rather than the ~2x of “buffer the blob, then decode it”.

The word source must yield the frame length word first, then payload words, exactly as frame_words_from_bytes lays them out.

Implementations

impl<F: FnMut() -> u32> FramedReader<F>

pub fn new(read_word: F) -> Self

Consume the leading length word and prepare to stream the payload.

pub fn payload_len(&self) -> usize

Total framed payload length in bytes (from the leading length word).

pub fn remaining(&self) -> usize

Payload bytes not yet handed to the decoder; zero once fully consumed. A non-zero value after a successful decode means trailing bytes.

pub fn discard_rest_of_frame(&mut self)

Pull and discard any payload words the decoder did not consume, leaving the source positioned at the next frame’s length word. Buffered/decoded data is not touched, so Self::remaining still reports trailing bytes.

Callers should invoke this before returning — success or failure — so a rejected frame does not desync a subsequent read, matching the buffered read_framed_bytes_with which always consumes the whole frame.

Cost is bounded by the frame’s length word: draining an honestly-framed frame reads only the words the source actually holds, but a frame whose length word is far larger than its real content will issue that many read_word calls. This is only reachable via a caller that recovers from an error and keeps reading; it is not a concern for honestly-framed input (as the guest’s is) where the length word reflects the payload.

Trait Implementations

impl<F: FnMut() -> u32> FramedRead for FramedReader<F>

fn read(&mut self, out: &mut [u8]) -> Result<(), EndOfFrame>

Fill out completely, or return EndOfFrame without advancing if the frame does not hold that many more bytes.