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use std::io::{self, BufRead, BufReader, Read};
use std::str;
struct CharBufReader<R: Read> {
reader: BufReader<R>,
char_buffer: String,
}
impl<R: Read> CharBufReader<R> {
pub fn new(reader: BufReader<R>) -> CharBufReader<R> {
CharBufReader {
reader: reader,
char_buffer: String::new(),
}
}
pub fn fill_buf(&mut self)
-> std::result::Result<&str, io::Error>
{
loop {
let byte_buffer = self.reader.fill_buf()?;
match str::from_utf8(byte_buffer) {
Err(error) => {
let n_valid = error.valid_up_to();
if n_valid == 0 {
self.reader.consume(1);
} else {
match str::from_utf8(&byte_buffer[..n_valid]) {
Err(_) => {
self.reader.consume(1);
},
Ok(chars) => {
self.char_buffer.push_str(chars);
self.reader.consume(n_valid);
break;
},
}
}
},
Ok(chars) => {
self.char_buffer.push_str(chars);
let n_to_consume = byte_buffer.len();
self.reader.consume(n_to_consume);
break;
}
}
}
return Ok(&self.char_buffer);
}
pub fn consume(&mut self, amount: usize) {
self.char_buffer.replace_range(..amount, "");
println!("consume {:?}", self.char_buffer);
}
}
pub fn handle_input(input_stream: impl Read)
-> std::result::Result<(), io::Error>
{
let reader = BufReader::new(input_stream);
let mut reader = CharBufReader::new(reader);
let string = reader.fill_buf()?;
println!("top level {:?}", string);
let n_to_consume = string.len();
reader.consume(n_to_consume);
Ok(())
}
#[cfg(test)]
mod tests {
use super::*;
use std::io::Cursor;
#[test]
fn test_empty_input() {
let buffer = Cursor::new(vec![]);
let result = handle_input(buffer);
assert!(result.is_ok());
}
}
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