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use crate::{
codecs::DecodeV2,
core::util::{PartialBuffer, WriteBuffer},
};
use std::{io::Result, ops::ControlFlow, panic::AssertUnwindSafe};
#[derive(Debug)]
enum State {
Decoding,
Flushing,
Done,
Next,
Error(AssertUnwindSafe<std::io::Error>),
}
#[derive(Debug)]
pub struct Decoder {
state: State,
multiple_members: bool,
}
impl Default for Decoder {
fn default() -> Self {
Self {
state: State::Decoding,
multiple_members: false,
}
}
}
impl Decoder {
pub fn multiple_members(&mut self, enabled: bool) {
self.multiple_members = enabled;
}
pub fn do_poll_read(
&mut self,
output: &mut WriteBuffer<'_>,
decoder: &mut dyn DecodeV2,
input: &mut PartialBuffer<&[u8]>,
mut first: bool,
) -> ControlFlow<Result<()>> {
loop {
self.state = match self.state {
State::Decoding => {
if input.unwritten().is_empty() && !first {
// Avoid attempting to reinitialise the decoder if the
// reader has returned EOF.
self.multiple_members = false;
State::Flushing
} else {
match decoder.decode(input, output) {
Ok(true) => State::Flushing,
// ignore the first error, occurs when input is empty
// but we need to run decode to flush
Err(err) if !first => {
self.state = State::Error(AssertUnwindSafe(err));
if output.written_len() > 0 {
return ControlFlow::Break(Ok(()));
} else {
continue;
}
}
// poll for more data for the next decode
_ => break,
}
}
}
State::Flushing => {
match decoder.finish(output) {
Ok(true) => {
if self.multiple_members {
if let Err(err) = decoder.reinit() {
self.state = State::Error(AssertUnwindSafe(err));
if output.written_len() > 0 {
return ControlFlow::Break(Ok(()));
} else {
continue;
}
}
// The decode stage might consume all the input,
// the next stage might need to poll again if it's empty.
first = true;
State::Next
} else {
State::Done
}
}
Ok(false) => State::Flushing,
Err(err) => {
self.state = State::Error(AssertUnwindSafe(err));
if output.written_len() > 0 {
return ControlFlow::Break(Ok(()));
} else {
continue;
}
}
}
}
State::Done => return ControlFlow::Break(Ok(())),
State::Next => {
if input.unwritten().is_empty() {
if first {
// poll for more data to check if there's another stream
break;
}
State::Done
} else {
State::Decoding
}
}
State::Error(_) => {
let State::Error(err) = std::mem::replace(&mut self.state, State::Done) else {
unreachable!()
};
return ControlFlow::Break(Err(err.0));
}
};
if output.has_no_spare_space() {
return ControlFlow::Break(Ok(()));
}
}
if output.has_no_spare_space() {
ControlFlow::Break(Ok(()))
} else {
ControlFlow::Continue(())
}
}
}
macro_rules! impl_decoder {
() => {
use crate::generic::bufread::Decoder as GenericDecoder;
use std::{ops::ControlFlow, task::ready};
use pin_project_lite::pin_project;
pin_project! {
#[derive(Debug)]
pub struct Decoder<R, D> {
#[pin]
reader: R,
decoder: D,
inner: GenericDecoder,
}
}
impl<R: AsyncBufRead, D: DecodeV2> Decoder<R, D> {
pub fn new(reader: R, decoder: D) -> Self {
Self {
reader,
decoder,
inner: GenericDecoder::default(),
}
}
}
impl<R, D> Decoder<R, D> {
pub fn get_ref(&self) -> &R {
&self.reader
}
pub fn get_mut(&mut self) -> &mut R {
&mut self.reader
}
pub fn get_pin_mut(self: Pin<&mut Self>) -> Pin<&mut R> {
self.project().reader
}
pub fn into_inner(self) -> R {
self.reader
}
pub fn multiple_members(&mut self, enabled: bool) {
self.inner.multiple_members(enabled);
}
}
fn do_poll_read(
inner: &mut GenericDecoder,
decoder: &mut dyn DecodeV2,
mut reader: Pin<&mut dyn AsyncBufRead>,
cx: &mut Context<'_>,
output: &mut WriteBuffer<'_>,
) -> Poll<Result<()>> {
if let ControlFlow::Break(res) =
inner.do_poll_read(output, decoder, &mut PartialBuffer::new(&[][..]), true)
{
return Poll::Ready(res);
}
loop {
let mut input = PartialBuffer::new(match reader.as_mut().poll_fill_buf(cx)? {
Poll::Ready(input) => input,
Poll::Pending if output.written().is_empty() => return Poll::Pending,
_ => return Poll::Ready(Ok(())),
});
let control_flow = inner.do_poll_read(output, decoder, &mut input, false);
let bytes_read = input.written().len();
reader.as_mut().consume(bytes_read);
if let ControlFlow::Break(res) = control_flow {
break Poll::Ready(res);
}
}
}
impl<R: AsyncBufRead, D: DecodeV2> Decoder<R, D> {
fn do_poll_read(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
output: &mut WriteBuffer<'_>,
) -> Poll<Result<()>> {
let this = self.project();
do_poll_read(this.inner, this.decoder, this.reader, cx, output)
}
}
};
}
pub(crate) use impl_decoder;