use crate::{    borrowed::{Band, Text},    PacketLine, Provider, MAX_DATA_LEN,};use std::io; /// An implementor of [`BufRead`][io::BufRead] yielding packet lines on each call to [`read_line()`][io::BufRead::read_line()]./// It's also possible to hide the underlying packet lines using the [`Read`][io::Read] implementation which is useful/// if they represent binary data, like the one of a pack file.////// # Performance Notice/// Reading from this intermediary copies bytes 3 times:/// OS -> (parent) line provider buffer -> our buffer -> caller's output buffer/// which won't make this very efficient for huge bandwidths.pub struct ReadWithSidebands<'a, T, F>where    T: io::Read,{    parent: &'a mut Provider<T>,    handle_progress: Option<F>,    buf: Vec<u8>,    pos: usize,    cap: usize,} impl<'a, T, F> Drop for ReadWithSidebands<'a, T, F>where    T: io::Read,{    fn drop(&mut self) {        self.parent.reset();    }} impl<'a, T> ReadWithSidebands<'a, T, fn(bool, &[u8])>where    T: io::Read,{    /// Create a new instance with the given provider as `parent`.    pub fn new(parent: &'a mut Provider<T>) -> Self {        ReadWithSidebands {            parent,            handle_progress: None,            buf: vec![0; MAX_DATA_LEN],            pos: 0,            cap: 0,        }    }} impl<'a, T, F> ReadWithSidebands<'a, T, F>where    T: io::Read,    F: FnMut(bool, &[u8]),{    /// Create a new instance with the given `parent` provider and the `handle_progress` function.    ///    /// Progress or error information will be passed to the given `handle_progress(is_error, text)` function, with `is_error: bool`    /// being true in case the `text` is to be interpreted as error.    pub fn with_progress_handler(parent: &'a mut Provider<T>, handle_progress: F) -> Self {        ReadWithSidebands {            parent,            handle_progress: Some(handle_progress),            buf: vec![0; MAX_DATA_LEN],            pos: 0,            cap: 0,        }    }     /// Create a new instance without a progress handler.    pub fn without_progress_handler(parent: &'a mut Provider<T>) -> Self {        ReadWithSidebands {            parent,            handle_progress: None,            buf: vec![0; MAX_DATA_LEN],            pos: 0,            cap: 0,        }    }     /// Forwards to the parent [Provider::reset_with()]    pub fn reset_with(&mut self, delimiters: &'static [PacketLine<'static>]) {        self.parent.reset_with(delimiters)    }     /// Forwards to the parent [Provider::stopped_at()]    pub fn stopped_at(&self) -> Option<PacketLine<'static>> {        self.parent.stopped_at    }     /// Set or unset the progress handler.    pub fn set_progress_handler(&mut self, handle_progress: Option<F>) {        self.handle_progress = handle_progress;    }     /// Effectively forwards to the parent [Provider::peek_line()], allowing to see what would be returned    /// next on a call to [`read_line()`][io::BufRead::read_line()].    pub fn peek_data_line(&mut self) -> Option<io::Result<Result<&[u8], crate::decode::Error>>> {        match self.parent.peek_line() {            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)),            _ => None,        }    }} impl<'a, T, F> io::BufRead for ReadWithSidebands<'a, T, F>where    T: io::Read,    F: FnMut(bool, &[u8]),{    fn fill_buf(&mut self) -> io::Result<&[u8]> {        use io::Read;        if self.pos >= self.cap {            debug_assert!(self.pos == self.cap);            self.cap = loop {                let line = match self.parent.read_line() {                    Some(line) => line?.map_err(|err| io::Error::new(io::ErrorKind::Other, err))?,                    None => break 0,                };                match self.handle_progress.as_mut() {                    Some(handle_progress) => {                        let mut band = line                            .decode_band()                            .map_err(|err| io::Error::new(io::ErrorKind::Other, err))?;                        match band {                            Band::Data(ref mut d) => break d.read(&mut self.buf)?,                            Band::Progress(d) => {                                let text = Text::from(d).0;                                handle_progress(false, text);                            }                            Band::Error(d) => {                                let text = Text::from(d).0;                                handle_progress(true, text);                            }                        };                    }                    None => {                        break match line.as_slice() {                            Some(ref mut d) => d.read(&mut self.buf)?,                            None => {                                return Err(io::Error::new(                                    io::ErrorKind::UnexpectedEof,                                    "encountered non-data line in a data-line only context",                                ))                            }                        }                    }                }            };            self.pos = 0;        }        Ok(&self.buf[self.pos..self.cap])    }     fn consume(&mut self, amt: usize) {        self.pos = std::cmp::min(self.pos + amt, self.cap);    }     fn read_line(&mut self, buf: &mut String) -> io::Result<usize> {        assert_eq!(            self.cap, 0,            "we don't support partial buffers right now - read-line must be used consistently"        );        let line = std::str::from_utf8(self.fill_buf()?)            .map_err(|err| io::Error::new(io::ErrorKind::Other, err))            .unwrap();        buf.push_str(line);        let bytes = line.len();        self.cap = 0;        Ok(bytes)    }} impl<'a, T, F> io::Read for ReadWithSidebands<'a, T, F>where    T: io::Read,    F: FnMut(bool, &[u8]),{    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {        use std::io::BufRead;        let nread = {            let mut rem = self.fill_buf()?;            rem.read(buf)?        };        self.consume(nread);        Ok(nread)    }}