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

Reactive streams & subscription primitives for constructing dataflow graphs / pipelines

import { SEMAPHORE } from "@thi.ng/api/api";
import {
  State
} from "./api.js";
import { ASidechain } from "./asidechain.js";
import { __optsWithID } from "./idgen.js";
const sidechainTrigger = (src, side, opts) => src.subscribe(new SidechainTrigger(side, opts));
class SidechainTrigger extends ASidechain {
  buf = SEMAPHORE;
  constructor(side, opts) {
    opts = __optsWithID("sidetrigger", opts);
    super(opts);
    const pred = opts.pred || (() => true);
    this.sideSub = side.subscribe({
      next: (x) => {
        if (this.buf !== SEMAPHORE && pred(x)) {
          this.dispatch(this.buf);
        }
      },
      done: () => this.done()
    });
  }
  next(x) {
    if (this.state < State.DONE) {
      this.buf = x;
    }
  }
}
export {
  SidechainTrigger,
  sidechainTrigger
};