Is there a way to get Stream<Token=char> from io::Read?

[tailhook]

Hi!

I'm seeing examples of how to parse and decode bytes from io::Read, but still not clear is now to do the same to have char stream (and also preferably with byte positioner). I find using chars easier for some use cases. Is there any built-in or easily accessible way to do that, or do I have to implement custom stream for that?

[Marwes]

The Read stream

combine/src/stream/read.rs

Lines 157 to 175 in fdd63e2

	pub struct Stream<R> {
	bytes: Bytes<R>,
	}
	impl<R: Read> StreamOnce for Stream<R> {
	type Token = u8;
	type Range = &'static [u8];
	type Position = usize;
	type Error = Error;
	#[inline]
	fn uncons(&mut self) -> Result<u8, StreamErrorFor<Self>> {
	match self.bytes.next() {
	Some(Ok(b)) => Ok(b),
	Some(Err(err)) => Err(Error::Io(err)),
	None => Err(Error::EndOfInput),
	}
	}
	}

uses https://doc.rust-lang.org/std/io/trait.Read.html#method.bytes internally however there is no equivalent for reading char directly from an io::Read so you would need to implement that first.

If at all possible I would recommend against parsing directly from a io::Read as it is significantly slower than reading from an in memory buffer. If you need streaming you may want to look into using https://docs.rs/combine/4.6.2/combine/macro.decode.html and partial parsing instead, it may be easier to create an input stream that contains a &[u8], yet returns char/&str (might be a good addition to combine itself actually).