Opstream

Pear operations stream base class

Readable stream wrapper around an async op(params) function.

Emits status object data events, at minimum:

• zero or one { tag: 'error', ... } objects - logical errors from op, not stream errors
• exactly one { tag: 'final', ... } object

For convenience consumer counterpart library see pear-opwait.

Install

npm install pear-opstream

API: new Opstream(op, params, done?)

Create a new Opstream Instance.

Parameters

• op: (params) => Promise<any> Async function called once when the stream eagerly reads.

• params: Object Input passed into op.

  • if `params.linka is present, it is normalized at origin:

    params.link = plink.normalize(params.link)

• done?: () => void Optional callback once emitted after the final chunk and stream ends.

Emitted data status objects

• if op rejects.

  {
    tag: 'error',
    data: { stack, code, message, success: false, info }
  }

• final status object always emitted exactly once:

  {
    tag: 'final',
    data: { success, ...final }
  }

Custom final

The { tag: 'final', ... } status object merges with instance.final.

Set this.final in subclass to declare final return value of opstream.

this.final = { result: 42 }

final chunk:

{
  tag: 'final',
  data: { success: true, result: 42 }
}

License

Apache-2.0