Front-end and full stack web developer
AoC 2019, Day 5: Sunny with a Chance of Asteroids
/**
* HoF that returns a function that performs an operation given by `fn`. The returned function takes an
* array `mem` (memory) and integer `ip` (instruction pointer). It returns a 2-tuple of the operation's
* optional output and the next position of the instruction pointer.
* @param {function(Array<number>, ...Array<number>)} fn
* @return {function(Array<number>, number): Array<(number|null)>}
*/
function op(fn) {
const arity = fn.length - 1;
const fn2 = (mem, ip) => {
const nextIp = ip + arity + 1;
let modes = Math.floor(mem[ip] / 100);
const params = mem.slice(ip + 1, nextIp).map(p => {
const mode = modes % 10;
modes = Math.floor(modes / 10);
return [getParamValue(mem, p, mode), p];
});
const [output = null, setIp = null] = fn(mem, ...params);
return [setIp === null ? nextIp : setIp, output];
};
fn2.arity = fn.length - 1;
return fn2;
}
function getParamValue(mem, param, mode) {
switch (mode) {
case ParamMode.POSITION:
return mem[param];
case ParamMode.IMMEDIATE:
return param;
default:
throw new Error(`Invalid mode '${mode}'`);
}
}
Ops1 = programInput => ({
[Opcode.ADD]: op((mem, [v1], [v2], [, p3]) => ((mem[p3] = v1 + v2), [])),
[Opcode.MULT]: op((mem, [v1], [v2], [, p3]) => ((mem[p3] = v1 * v2), [])),
// takes a single integer as input and saves it to the position given by its only parameter
[Opcode.GET]: op((mem, [, p1]) => ((mem[p1] = parseInt(programInput)), [])),
// outputs the value of its only parameter
[Opcode.PUT]: op((_, [v1]) => [v1]),
[Opcode.HALT]: op(_ => [null, -1])
})
function getPerformInstruction(ops) {
return (prog, ip) => {
const opcode = prog[ip] % 100;
if (opcode in ops) {
return ops[opcode](prog, ip);
}
throw new Error(`Invalid opcode '${opcode}' at ${ip}`);
};
}
function* evaluateIntcode(prog, ops) {
let ip = 0;
let output;
const performInstruction = getPerformInstruction(ops);
while (ip !== -1 && ip < prog.length) {
[ip, output] = performInstruction(prog, ip);
if (output !== null) {
yield output;
}
}
}
Ops2 = programInput =>
Object.assign(Ops1(programInput), {
// If the first parameter is non-zero, it sets the instruction pointer to the value from the second
// parameter. Otherwise, it does nothing.
[Opcode2.JUMP_IF_TRUE]: op((_, [v1], [v2]) =>
v1 === 0 ? [] : [null, v2]
),
// If the first parameter is zero, it sets the instruction pointer to the value from the second
// parameter. Otherwise, it does nothing.
[Opcode2.JUMP_IF_FALSE]: op((_, [v1], [v2]) =>
v1 === 0 ? [null, v2] : []
),
// If the first parameter is less than the second parameter, it stores 1 in the position given by the
// third parameter. Otherwise, it stores 0.
[Opcode2.LESS_THAN]: op(
(mem, [v1], [v2], [, p3]) => ((mem[p3] = +(v1 < v2)), [])
),
// If the first parameter is equal to the second parameter, it stores 1 in the position given by the
// third parameter. Otherwise, it stores 0.
[Opcode2.EQUALS]: op(
(mem, [v1], [v2], [, p3]) => ((mem[p3] = +(v1 === v2)), [])
)
})
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