@thi.ng/rstream/object.js

Reactive streams & subscription primitives for constructing dataflow graphs / pipelines

import { dedupe } from "@thi.ng/transducers/dedupe";
import { range } from "@thi.ng/transducers/range";
import { __optsWithID } from "./idgen.js";
import { Subscription, subscription } from "./subscription.js";
const fromObject = (src, opts = {}) => new StreamObj(src, opts);
const fromTuple = (src, opts) => new StreamObj(src, { keys: [...range(src.length)], ...opts });
class StreamObj extends Subscription {
  /**
   * Object of managed & typed streams for registered keys.
   */
  keys;
  streams = {};
  defaults;
  constructor(src, opts = {}) {
    super(void 0, __optsWithID("obj", opts));
    this.keys = opts.keys || Object.keys(src);
    this.defaults = opts.defaults;
    const _opts = opts.dedupe !== false ? {
      xform: dedupe(opts.equiv || ((a, b) => a === b)),
      ...opts
    } : opts;
    for (const k of this.keys) {
      this.streams[k] = subscription(void 0, {
        ..._opts,
        id: `${this.id}-${k}`
      });
    }
    opts.initial !== false && this.next(src);
  }
  /**
   * Receives an object of configured type and feeds each key's new value into
   * its respective {@link StreamObj.streams}. If the
   * {@link StreamObjOpts.defaults} option is given, `undefined` key values
   * are replaced with their specified default. If
   * {@link StreamObjOpts.dedupe} is enabled (default) only changed values (as
   * per {@link StreamObjOpts.equiv} predicate option) will be propagated
   * downstream.
   *
   * @param x -
   */
  next(x) {
    this.cacheLast && (this.last = x);
    for (const k of this.keys) {
      const val = x[k];
      this.streams[k].next(
        this.defaults && val === void 0 ? this.defaults[k] : val
      );
    }
    super.next(x);
  }
  done() {
    for (const k of this.keys) {
      this.streams[k].done?.();
    }
    super.done();
  }
  unsubscribe(sub) {
    if (!sub) {
      for (const k of this.keys) {
        this.streams[k].unsubscribe();
      }
    }
    return super.unsubscribe(sub);
  }
}
export {
  StreamObj,
  fromObject,
  fromTuple
};