position_smart_pointer.rs

use std::ops::{Deref, DerefMut, Range};

/// Position is a smart-pointer kind of type that wraps an inner value
/// with position information.
#[derive(Debug, Eq, PartialEq)]
pub struct Position<T> {
    position: Range<usize>,
    inner: T,
}

impl<T> Position<T> {
    pub fn new(inner: T, position: Range<usize>) -> Self {
        Self { inner, position }
    }

    pub fn position(&self) -> Range<usize> {
        self.position.clone()
    }
}

impl<T> Deref for Position<T> {
    type Target = T;

    fn deref(&self) -> &Self::Target {
        &self.inner
    }
}

impl<T> DerefMut for Position<T> {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.inner
    }
}

#[derive(Debug)]
enum Token {
    If,
    Else,
    Ident(String),
    Int(i64),
    Uint(u64),
    Float(f64)
}

fn main() {
    let token = Position::new(
        Token::Ident("hallo".to_string()),
        42..45
    );
    println!("position {:?}", token.position());
    println!("token {:?}", token)
}