hanoi.js

function execute(prog, input) {
    class Tower {
        #arr
        #fill
        #writeonly
        constructor(arr, fill, writeonly = false) {
            this.#arr = arr;
            this.#fill = fill;
            this.#writeonly = writeonly;
        }
        push(val) {
            if (!this.#writeonly && (this.#arr.length > 0 ? val > this.#arr.at(-1) : val > this.#fill))
                throw new Error('ERROR: TOWERS OF HANOI RULE BORKEN');
            this.#arr.push(val);
        }
        pop() {
            if (this.#arr.length > 0) return this.#arr.pop();
            return this.#fill;
        }
        get arr() {
            return this.#arr;
        }
    }
    let istack = new Tower(input.split('').map((_,i,a)=>a[a.length-i-1].charCodeAt(0)), 0);
    let ostack = new Tower([], 0, true);
    let stack1 = new Tower([], 255);
    let stack2 = new Tower([], 255);
    let stack3 = new Tower([], 255);
    for (const char of prog)
        switch (char) {
            case '-': {
                let a = stack2.pop();
                let b = stack2.pop();
                stack2.push(b);
                stack2.push(b - a);
                break;
            }
            case '>': {
                let a = stack2.pop();
                stack2.push(a);
                stack2.push(a);
                break;
            }
            case '<': {
                let a1 = stack2.pop();
                let a2 = stack2.pop();
                if (a1 != a2)
                    throw new Error('ERROR: IRREVERSIBLE OPERATION');
                stack2.push(a1);
                break;
            }
            case '(': {
                let x = stack1.pop();
                stack2.push(x);
                break;
            }
            case ')': {
                let x = stack2.pop();
                stack1.push(x);
                break;
            }
            case '[': {
                let x = stack3.pop();
                stack2.push(x);
                break;
            }
            case ']': {
                let x = stack2.pop();
                stack3.push(x);
                break;
            }
            case '{': {
                let x = istack.pop();
                stack2.push(x);
                break;
            }
            case '}': {
                let x = stack2.pop();
                ostack.push(x);
                break;
            }
        }
    return ostack.arr.map((_,i,a) => String.fromCharCode(a[a.length - i - 1])).join('');
}