LOR1

lor1.rs

#[derive(Debug, Default, Clone, Copy)]
struct LexerT<'a> {
    pos: usize,
    text: &'a str,
    token: &'a str,
} 

fn next_token(state: LexerT) -> Option<LexerT> {
    let mut start_pos = 0;
    let mut end_pos = start_pos;
    let ref slice = state.text[state.pos .. state.text.len()];
    for ch in slice.chars() {  
        if ch.is_alphabetic()  {
            end_pos += 1;
        } else if start_pos == end_pos {
            if ch.is_whitespace() {
                start_pos += 1;
                end_pos += 1;
                continue;
            } else {
                end_pos += 1;
                break;
            }
        } else {
            break;
        }
    }
    if start_pos != end_pos {
        Some(LexerT {pos: end_pos, text: slice, token: &slice[start_pos..end_pos]})
    } else {
        None
    }
}

fn main() {
    let mut lexer = LexerT {pos: 0, text: "Hello, world!", token: ""};
    while let Some(lexer_now) = next_token(lexer) {        
        lexer = lexer_now;
        println!("{:?}", lexer_now);
    }
}