@thi.ng/rstream/stream.js

Reactive streams & subscription primitives for constructing dataflow graphs / pipelines

import { isFunction } from "@thi.ng/checks/is-function";
import { __optsWithID } from "./idgen.js";
import { LOGGER } from "./logger.js";
import { Subscription } from "./subscription.js";
function stream(src, opts) {
  return new Stream(src, opts);
}
const reactive = (val, opts) => {
  const res = new Stream(opts);
  res.next(val);
  return res;
};
class Stream extends Subscription {
  src;
  _cancel;
  _inited;
  constructor(src, opts) {
    const [_src, _opts] = isFunction(src) ? [src, opts || {}] : [void 0, src || {}];
    super(
      _opts.error ? { error: _opts.error } : void 0,
      __optsWithID("stream", _opts)
    );
    this.src = _src;
    this._inited = false;
  }
  subscribe(sub, opts = {}) {
    const $sub = super.subscribe(sub, opts);
    if (!this._inited) {
      if (this.src) {
        try {
          this._cancel = this.src(this) || (() => void 0);
        } catch (e) {
          let s = this.wrapped;
          if (!s || !s.error || !s.error(e)) {
            this.unhandledError(e);
          }
        }
      }
      this._inited = true;
    }
    return $sub;
  }
  unsubscribe(sub) {
    const res = super.unsubscribe(sub);
    if (res && (!sub || (!this.subs || !this.subs.length) && this.closeOut !== "never")) {
      this.cancel();
    }
    return res;
  }
  done() {
    this.cancel();
    super.done();
    delete this.src;
    delete this._cancel;
  }
  error(e) {
    if (super.error(e)) return true;
    this.cancel();
    return false;
  }
  cancel() {
    if (this._cancel) {
      LOGGER.debug(this.id, "cancel");
      const f = this._cancel;
      delete this._cancel;
      f();
    }
  }
}
export {
  Stream,
  reactive,
  stream
};