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

Reactive streams & subscription primitives for constructing dataflow graphs / pipelines

import { peek } from "@thi.ng/arrays/peek";
import { map } from "@thi.ng/transducers/map";
import {
  State
} from "./api.js";
import { ASidechain } from "./asidechain.js";
import { __optsWithID } from "./idgen.js";
import { fromRAF } from "./raf.js";
const sidechainPartition = (src, side, opts) => src.subscribe(new SidechainPartition(side, opts));
const sidechainPartitionRAF = (src) => sidechainPartition(src, fromRAF()).transform(map(peek));
class SidechainPartition extends ASidechain {
  buf;
  constructor(side, opts) {
    opts = __optsWithID("sidepart", opts);
    super(opts);
    const pred = opts.pred || (() => true);
    this.buf = [];
    this.sideSub = side.subscribe({
      next: (x) => {
        if (this.buf.length && pred(x)) {
          this.dispatch(this.buf);
          this.buf = [];
        }
      },
      done: () => {
        if (this.buf.length) {
          this.dispatch(this.buf);
        }
        this.done();
        delete this.buf;
      }
    });
  }
  next(x) {
    if (this.state < State.DONE) {
      this.buf.push(x);
    }
  }
}
export {
  SidechainPartition,
  sidechainPartition,
  sidechainPartitionRAF
};