zustand-computed/dist/index.mjs

A Zustand middleware to create computed states.

const isIterable = (obj) => Symbol.iterator in obj;
const hasIterableEntries = (value) => (
  // HACK: avoid checking entries type
  "entries" in value
);
const compareEntries = (valueA, valueB) => {
  const mapA = valueA instanceof Map ? valueA : new Map(valueA.entries());
  const mapB = valueB instanceof Map ? valueB : new Map(valueB.entries());
  if (mapA.size !== mapB.size) {
    return false;
  }
  for (const [key, value] of mapA) {
    if (!Object.is(value, mapB.get(key))) {
      return false;
    }
  }
  return true;
};
const compareIterables = (valueA, valueB) => {
  const iteratorA = valueA[Symbol.iterator]();
  const iteratorB = valueB[Symbol.iterator]();
  let nextA = iteratorA.next();
  let nextB = iteratorB.next();
  while (!nextA.done && !nextB.done) {
    if (!Object.is(nextA.value, nextB.value)) {
      return false;
    }
    nextA = iteratorA.next();
    nextB = iteratorB.next();
  }
  return !!nextA.done && !!nextB.done;
};
function shallow(valueA, valueB) {
  if (Object.is(valueA, valueB)) {
    return true;
  }
  if (typeof valueA !== "object" || valueA === null || typeof valueB !== "object" || valueB === null) {
    return false;
  }
  if (!isIterable(valueA) || !isIterable(valueB)) {
    return compareEntries(
      { entries: () => Object.entries(valueA) },
      { entries: () => Object.entries(valueB) }
    );
  }
  if (hasIterableEntries(valueA) && hasIterableEntries(valueB)) {
    return compareEntries(valueA, valueB);
  }
  return compareIterables(valueA, valueB);
}
const computedImpl = (compute, opts) => (f) => {
  const optsKeys = !opts || !("keys" in opts) || opts.keys == null ? void 0 : opts.keys;
  const keysSet = optsKeys ? new Set(optsKeys) : void 0;
  function defaultShouldRecomputeFn(_, nextState) {
    if (!keysSet || nextState == null) return true;
    return Object.keys(nextState).some((k) => keysSet.has(k));
  }
  const shouldRecomputeFn = opts && "shouldRecompute" in opts ? opts.shouldRecompute ?? defaultShouldRecomputeFn : defaultShouldRecomputeFn;
  return (set, get, api) => {
    const equalityFn = (opts == null ? void 0 : opts.equalityFn) ?? shallow;
    const computeAndMerge = (state) => {
      const computedState = compute({ ...state });
      for (const k of Object.keys(computedState)) {
        if (equalityFn(computedState[k], state[k])) {
          delete computedState[k];
        }
      }
      return { ...state, ...computedState };
    };
    const setWithComputed = (update, replace, ...args) => {
      set(
        (state) => {
          const updated = typeof update === "object" ? update : update(state);
          if (!(shouldRecomputeFn == null ? void 0 : shouldRecomputeFn(state, updated))) return { ...state, ...updated };
          return computeAndMerge({ ...state, ...updated });
        },
        replace,
        ...args
      );
    };
    const _api = api;
    _api.setState = setWithComputed;
    const st = f(setWithComputed, get, _api);
    return Object.assign({}, st, compute(st));
  };
};
const createComputed = computedImpl;
export {
  createComputed
};