Revert "Revert "[git-packetline] It compiles with parent as option, even with state machine""

This reverts commit 890cc50.

Author: Byron

git-packetline/src/read/sidebands/async_io.rs

@@ -30,8 +30,8 @@ where
     T: AsyncRead,
 {
     fn drop(&mut self) {
-        if let State::Idle { parent } = self.state {
-            parent.reset();
+        if let State::Idle { ref mut parent } = self.state {
+            parent.as_mut().unwrap().reset();
         }
     }
 }
@@ -43,7 +43,7 @@ where
     /// Create a new instance with the given provider as `parent`.
     pub fn new(parent: &'a mut StreamingPeekableIter<T>) -> Self {
         WithSidebands {
-            state: State::Idle { parent },
+            state: State::Idle { parent: Some(parent) },
             handle_progress: None,
             pos: 0,
             cap: 0,
@@ -53,7 +53,7 @@ where
 
 enum State<'a, T> {
     Idle {
-        parent: &'a mut StreamingPeekableIter<T>,
+        parent: Option<&'a mut StreamingPeekableIter<T>>,
     },
     ReadLine {
         read_line: Pin<Box<dyn Future<Output = ReadLineResult<'a>> + 'a>>,
@@ -72,7 +72,7 @@ where
     /// being true in case the `text` is to be interpreted as error.
     pub fn with_progress_handler(parent: &'a mut StreamingPeekableIter<T>, handle_progress: F) -> Self {
         WithSidebands {
-            state: State::Idle { parent },
+            state: State::Idle { parent: Some(parent) },
             handle_progress: Some(handle_progress),
             pos: 0,
             cap: 0,
@@ -82,7 +82,7 @@ where
     /// Create a new instance without a progress handler.
     pub fn without_progress_handler(parent: &'a mut StreamingPeekableIter<T>) -> Self {
         WithSidebands {
-            state: State::Idle { parent },
+            state: State::Idle { parent: Some(parent) },
             handle_progress: None,
             pos: 0,
             cap: 0,
@@ -92,14 +92,14 @@ where
     /// Forwards to the parent [StreamingPeekableIter::reset_with()]
     pub fn reset_with(&mut self, delimiters: &'static [PacketLine<'static>]) {
         if let State::Idle { ref mut parent } = self.state {
-            parent.reset_with(delimiters)
+            parent.as_mut().unwrap().reset_with(delimiters)
         }
     }
 
     /// Forwards to the parent [StreamingPeekableIter::stopped_at()]
     pub fn stopped_at(&self) -> Option<PacketLine<'static>> {
         match self.state {
-            State::Idle { ref parent } => parent.stopped_at,
+            State::Idle { ref parent } => parent.as_ref().unwrap().stopped_at,
             _ => None,
         }
     }
@@ -113,7 +113,7 @@ where
     /// next on a call to [`read_line()`][io::BufRead::read_line()].
     pub async fn peek_data_line(&mut self) -> Option<std::io::Result<Result<&[u8], crate::decode::Error>>> {
         match self.state {
-            State::Idle { ref mut parent } => match parent.peek_line().await {
+            State::Idle { ref mut parent } => match parent.as_mut().unwrap().peek_line().await {
                 Some(Ok(Ok(crate::PacketLine::Data(line)))) => Some(Ok(Ok(line))),
                 Some(Ok(Err(err))) => Some(Ok(Err(err))),
                 Some(Err(err)) => Some(Err(err)),
@@ -133,19 +133,21 @@ where
         use futures_lite::FutureExt;
         use std::io;
         {
-            let this = self.get_mut();
+            let this = self.as_mut().get_mut();
             if this.pos >= this.cap {
                 let (ofs, cap) = loop {
                     match this.state {
                         State::Idle { ref mut parent } => {
+                            let parent = parent.take().unwrap();
+                            let inactive = parent as *mut _;
                             this.state = State::ReadLine {
                                 read_line: parent.read_line().boxed(),
-                                parent_inactive: *parent as *mut _,
+                                parent_inactive: inactive,
                             }
                         }
                         State::ReadLine {
                             ref mut read_line,
-                            parent_inactive,
+                            parent_inactive: _,
                         } => {
                             let line = match ready!(read_line.poll(cx)) {
                                 Some(line) => line?.map_err(|err| io::Error::new(io::ErrorKind::Other, err))?,
@@ -189,14 +191,15 @@ where
             }
         }
         let range = self.pos..self.cap;
-        match self.state {
-            State::Idle { parent } => Poll::Ready(Ok(&parent.buf[range])),
+        match self.get_mut().state {
+            State::Idle { ref parent } => Poll::Ready(Ok(&parent.as_ref().unwrap().buf[range])),
             State::ReadLine { .. } => unreachable!("at least in theory"),
         }
     }
 
     fn consume(self: Pin<&mut Self>, amt: usize) {
-        self.pos = std::cmp::min(self.pos + amt, self.cap);
+        let this = self.get_mut();
+        this.pos = std::cmp::min(this.pos + amt, this.cap);
     }
 }