@thi.ng/rstream/sidechain-toggle.js

Reactive streams & subscription primitives for constructing dataflow graphs / pipelines

import {
  State
} from "./api.js";
import { ASidechain } from "./asidechain.js";
import { __optsWithID } from "./idgen.js";
const sidechainToggle = (src, side, opts) => src.subscribe(new SidechainToggle(side, opts));
class SidechainToggle extends ASidechain {
  isActive;
  constructor(side, opts) {
    opts = __optsWithID("sidetoggle", opts);
    super(opts);
    this.isActive = !!opts.initial;
    const pred = opts.pred || (() => true);
    this.sideSub = side.subscribe({
      next: (x) => {
        if (pred(x)) {
          this.isActive = !this.isActive;
        }
      },
      done: () => this.done()
    });
  }
  next(x) {
    if (this.isActive && this.state < State.DONE) {
      super.next(x);
    }
  }
}
export {
  SidechainToggle,
  sidechainToggle
};