lifetime parameters

gistfile1.rs

const BUFSIZE: usize = 64 * 1024;

use std::fs::File;
use std::io::Read;

struct Lexer<'a> {
    buf: & 'a mut [u8; BUFSIZE],
    len: usize,
    pos: usize,
    f: File,
}

impl<'a> Iterator for Lexer<'a> {
    type Item = &'a [u8];

    fn next(&mut self) -> Option<&'a [u8]> {
        if self.len == 0 {
            self.f.read(self.buf).ok().expect("Error reading file");
        }
        while self.pos < self.len && self.buf[self.pos] == b' ' {
            self.pos += 1;
        }
        let start = self.pos;
        while self.pos < self.len && self.buf[self.pos] != b' ' {
            self.pos += 1;
        }
        if start < self.pos {
            Some(&self.buf[start..self.pos])
        } else {
            None
        }
    }
}

fn main() {
    let lexer = Lexer {
        buf: &mut[0; BUFSIZE],
        len: 0,
        pos: 0,
        f: File::open("test.txt").ok().unwrap(),
    };
    for chunk in lexer {
        println!("{:?}", chunk);
    }
}