@wordpress/core-data/build-module/utils/with-weak-map-cache.js

Access to and manipulation of core WordPress entities.

/**
 * Given a function, returns an enhanced function which caches the result and
 * tracks in WeakMap. The result is only cached if the original function is
 * passed a valid object-like argument (requirement for WeakMap key).
 *
 * @param {Function} fn Original function.
 *
 * @return {Function} Enhanced caching function.
 */
function withWeakMapCache(fn) {
  const cache = new WeakMap();
  return key => {
    let value;
    if (cache.has(key)) {
      value = cache.get(key);
    } else {
      value = fn(key);

      // Can reach here if key is not valid for WeakMap, since `has`
      // will return false for invalid key. Since `set` will throw,
      // ensure that key is valid before setting into cache.
      if (key !== null && typeof key === 'object') {
        cache.set(key, value);
      }
    }
    return value;
  };
}
export default withWeakMapCache;
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