INTCODE-Interpreter

See here for a quick overview of what Intcode is.

See Advent of Code 2019, Day 2, Day 5, Day 7, Day 9 for the Intcode-specification, and many example programs.

A new interpreter can easily be created:

let code = vec![4,17,4,19,1001,17,1,17,8,17,18,16,1006,16,0,99,-1,1,11,32];
let pc = src::Interpreter::new(code.to_owned(), vec![].into());

Executing pc.step() steps through the instructions one by one, pc.step_loop() steps through the instructions until either of the following happens:

1. There is an output value.
2. The program is requesting input, but the input buffer is empty.
3. The program terminated.
4. The program encountered a syntax error while parsing, eg. a jump out of memory, or an incorrect opcode.

These results can easily be handled with a simple match statement. For example:

fn main() {
    let code = vec![3,21,1008,21,8,20,1005,20,22,107,8,21,20,1006,20,31,1106,0,36,98,0,0,1002,21,125,20,4,20,1105,1,46,104,999,1105,1,46,1101,1000,1,20,4,20,1105,1,46,98,99];

    let mut pc = src::Interpreter::new(code.to_owned(), vec![].into());

    loop {
        let res = pc.step_loop();
        match res {
            Ok(val) => println!("{}", val),
            Err(src::InterpreterError::NoInputError) => { pc.input_buffer.push_back(read_input()) },
            Err(src::InterpreterError::Terminated) => { break; },
            Err(e) => {
                println!("Error! {:?}", e);
                println!("{:?}", pc);
                break;
            }
        }
    }
}