Interpreter for the TapeBagel esoteric language

tapebagel.rs

/*
 * ----------------------------------------------------------------------------
 * "THE BEER-WARE LICENSE" (Revision 42):
 * <contact@f0rki.at> wrote this file.  As long as you retain this notice you
 * can do whatever you want with this stuff. If we meet some day, and you think
 * this stuff is worth it, you can buy me a beer in return.
 * ----------------------------------------------------------------------------
 */

/// Interpreter for the TapeBagel esoteric language
/// see https://esolangs.org/wiki/TapeBagel for a partial spec

use std::env;
use std::fs::File;
use std::io;
use std::io::{Read, BufRead};


struct TapeBagel {
    integers: [i64; 3],
    index: usize,
    output: String,
}


impl TapeBagel {
    fn new() -> TapeBagel {
        TapeBagel {
            integers: [0, 0, 0],
            index: 0,
            output: String::new(),
        }
    }

    fn set_all_ints_to(&mut self, val: i64) {
        for i in 0..self.integers.len() {
            self.integers[i] = val;
        }
    }

    fn pause(&self) {
        println!("Pause\nindex = {}", self.index);
        // let mut n = 0;
        for (n, i) in self.integers.iter().enumerate() {
            println!("i{} = {}", n, i);
            // n += 1;
        }
        println!("Continue?");
        let stdin = std::io::stdin();
        stdin.lock().lines().next().unwrap().unwrap();
    }

    fn clear_screen(&mut self) {
        println!("{}", self.output);
        self.output.clear();
    }


    fn handle_int_op(&mut self, cmd: &str) {
        let mut i1 = 0;
        let mut i = 0;
        let mut operator = ' ';
        for c in cmd.chars() {
            if c == '*' {
                i += 1
            } else {
                operator = c;
                i1 = i - 1;
                i = 0;
            }
        }
        let i2 = i - 1;

        // println!("operation: {} with {}, {}", operator, i1, i2);
        match operator {
            '&' => self.integers[self.index] = self.integers[i1] * self.integers[i2],
            '+' => self.integers[self.index] = self.integers[i1] + self.integers[i2],
            '$' => self.integers[self.index] = self.integers[i1] / self.integers[i2],
            '-' => self.integers[self.index] = self.integers[i1] - self.integers[i2],
            _ => panic!("Unkown operator '{}'", operator),
        }
        // println!("result = {}", self.integers[self.index]);
    }

    fn int_to_char(&self, i: i64) -> char {
        if i == 0 {
            return ' ';
        }
        let j: u32;
        j = (i as u32) + 64;
        std::char::from_u32(j).unwrap()
    }

    fn handle_print(&mut self, cmd: &str) {
        let mut i = 0;
        for c in cmd.chars() {
            if c == '*' {
                i += 1;
            }
        }
        if i == 0 {
            panic!("need some integer specifier");
        }
        i -= 1;
        if cmd.starts_with("@@") {
            // println!("print_int({}) = {}", i, self.integers[i]);
            let istr = self.integers[i].to_string();
            self.output.push_str(&istr);
        } else if cmd.starts_with("@") {
            let outchar = self.int_to_char(self.integers[i]);
            // println!("print_char({}) = {} = {}", i, self.integers[i], outchar);
            self.output.push(outchar);
        }
    }

    fn execute(&mut self, program: &str) -> String {
        self.output.clear();
        let mut institer = program.split_whitespace();
        loop {
            match institer.next() {
                Some(c) => {
                    match c {
                        "%#" => self.index += 1,
                        "%%" => self.index = 0,
                        "#%" => self.set_all_ints_to(1),
                        "##" => self.set_all_ints_to(0),
                        "&&" => self.pause(),
                        "&@" => self.clear_screen(),
                        "%++" => self.integers[self.index] += 1,
                        _ => {
                            if c.starts_with("@") {
                                self.handle_print(c);
                            } else if c.starts_with("*") {
                                self.handle_int_op(c);
                            } else {
                                println!("Invalid command '{}'", c);
                                break;
                            }
                        }
                    }
                }
                None => {
                    println!("Execution stop");
                    break;
                }
            }
        }
        self.output.clone()
    }
}


fn from_file(filepath: &str) -> io::Result<String> {
    let mut contents = Vec::new();
    let mut file = try!(File::open(filepath));
    try!(file.read_to_end(&mut contents));
    Ok(String::from_utf8(contents).unwrap())
}


fn main() {
    println!("TapeBagel.rs");
    let args: Vec<String> = env::args().collect();
    if args.len() == 2 {
        println!("Executing file '{}':", args[1]);
        let fcontents = from_file(&args[1]).unwrap();
        println!("{}", fcontents);

        let mut machine = TapeBagel::new();
        let out = machine.execute(&fcontents);
        println!("output:\n{}", out);
    } else {
        println!("usage: {} <path to input file>", args[0]);
    }
}

#[test]
fn test_hello_world() {
    let program_text = "%% %++ %++ %++ %++ %++ %++ %++ %++ @* ## %++ %++ %++ %++ %++ @* ## %++ \
                        %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ @* @* ## %++ %++ %++ %++ %++ \
                        %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ @* ## @* %++ %++ %++ %++ %++ %++ \
                        %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ @* ## \
                        %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ @* ## %++ %++ \
                        %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ @* ##  \
                        %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ %++ @* ## %++ %++ %++ %++ @* \
                        ## ";

    let mut machine = TapeBagel::new();
    let out = machine.execute(program_text);

    assert_eq!(out, "HELLO WORLD");
}


#[test]
fn test_iwctf() {
    let program_text = "## %% %++ %++ %++ %# *&* @** %# **&* ***-* ***-* %++ %++ @*** *-* @*** \
                        @** *+** @*** ***+* @*** **+** ***+* %++ @*** #% %% %++ %++ %++ %++ @* %# \
                        %++ %++ %++ %% *&** @* @*** *-** @* %# %++ @** *-** *-** **-*** **-*** \
                        **-*** @** @*** #% %% %++ %++ %++ %++ %# *+** %++ @** @* %# *+** @*** ## \
                        %% @***";

    let mut machine = TapeBagel::new();
    let out = machine.execute(program_text);

    assert_eq!(out, "IW ILOVETAPEBAGEL ");
}

I wonder who this elusive S. R. Farmer is who is mentioned on the TapeBagel wiki page... https://esolangs.org/wiki/TapeBagel