lexer.rs

/// 
/// A LashToken is a token in Lash. Every token has an associated value.
///

use std::io;
use std::result;


pub enum LashToken {
    Identifier(~str),
    Integer(i32),
    Float(f64),
    StringLiteral(~str),
    LParen,
    RParen,
    LBracket,
    RBracket,
    LBrace,
    RBrace,
    Dot,
    Comma,
    Operator(~str),
    Let,
    For,
    In,
    If,
    Else,
    Unless,
    Throw,
    Catch,
    As,
    Func,
    Nil,
    False,
    True,
    Using,
    From,
    Try,
    Rethrow,
    Finally
}

pub struct LashLexer<'a> {
    input_stream: &'a io::Reader,
    unget_stack : ~[u8],
    tokens      : ~[LashToken]
}

impl<'a> LashLexer<'a> {
    pub fn new(mut input: &'a mut io::Reader) -> ~LashLexer {
        ~LashLexer{
            input_stream: input,
            unget_stack: ~[],
            tokens: ~[]
        }
    }

    fn get_u8(&mut self) -> Result<u8, io::IoError> {
        match self.unget_stack.pop()  {
            Some(u8) => Ok(u8),
            None     => self.input_stream.read_byte(),
        }
    }

    fn unget_u8(&mut self, unget_char: u8) {
        self.unget_stack.push(unget_char);
    }
}

fn main() {
    println!("Hello world!");
}