@data-client/normalizr/lib/memo/WeakDependencyMap.js

Normalizes and denormalizes JSON according to schema for Redux and Flux applications

import { UNDEF } from '../denormalize/UNDEF.js';

/** Maps a (ordered) list of dependencies to a value.
 *
 * Useful as a memoization cache for flat/normalized stores.
 *
 * All dependencies are only weakly referenced, allowing automatic garbage collection
 * when any dependencies are no longer used.
 */
export default class WeakDependencyMap {
  constructor() {
    this.next = new WeakMap();
    this.nextPath = undefined;
  }
  get(entity, getDependency) {
    let curLink = this.next.get(entity);
    if (!curLink) return EMPTY;
    while (curLink.nextPath) {
      var _getDependency;
      // we cannot perform lookups with `undefined`, so we use a special object to represent undefined
      const nextEntity = (_getDependency = getDependency(curLink.nextPath)) != null ? _getDependency : UNDEF;
      curLink = curLink.next.get(nextEntity);
      if (!curLink) return EMPTY;
    }
    // curLink exists, but has no path - so must have a value
    return [curLink.value, curLink.journey];
  }
  set(dependencies, value) {
    if (dependencies.length < 1) throw new KeySize();
    let curLink = this;
    for (const {
      entity,
      path
    } of dependencies) {
      let nextLink = curLink.next.get(entity);
      if (!nextLink) {
        nextLink = new Link();
        // void members are represented as a symbol so we can lookup
        curLink.next.set(entity != null ? entity : UNDEF, nextLink);
      }
      curLink.nextPath = path;
      curLink = nextLink;
    }
    // in case there used to be more
    curLink.nextPath = undefined;
    curLink.value = value;
    // we could recompute this on get, but it would have a cost and we optimize for `get`
    curLink.journey = dependencies.map(dep => dep.path);
  }
}
const EMPTY = [undefined, undefined];

/** Link in a chain */
class Link {
  constructor() {
    this.next = new WeakMap();
    this.value = undefined;
    this.journey = [];
    this.nextPath = undefined;
  }
}
class KeySize extends Error {
  constructor(...args) {
    super(...args);
    this.message = 'Keys must include at least one member';
  }
}
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