https://github.com/slurmulon/generator-collector

:recycle: Lazily collect and query generators
https://github.com/slurmulon/generator-collector

coroutine generator iteration iterator lazy query

Last synced: about 2 months ago
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:recycle: Lazily collect and query generators

• Host: GitHub
• URL: https://github.com/slurmulon/generator-collector
• Owner: slurmulon
• Created: 2022-10-10T14:05:58.000Z (over 2 years ago)
• Default Branch: main
• Last Pushed: 2024-04-15T06:46:11.000Z (10 months ago)
• Last Synced: 2024-10-29T10:07:02.804Z (3 months ago)
• Topics: coroutine, generator, iteration, iterator, lazy, query
• Language: JavaScript
• Homepage: https://slurmulon.github.io/generator-collector
• Size: 902 KB
• Stars: 1
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Roadmap: docs/roadmap.md

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README

        
# generator-collector

> :recycle: Lazily collect and query generators in JS

---

> :warning: This project is **experimental** and should not be considered stable for production use.

## Features

- Collect and query generator results using coroutines

- Iterate only to the values you need, only when you need them

- Seamless integration with promises and async functions

## Resources

- :book: [Documentation](https://slurmulon.github.io/generator-collector)

- :anchor: [Install](https://slurmulon.github.io/generator-collector/#/install)

- :wrench: [API](https://slurmulon.github.io/generator-collector/#/api/)

- :bulb: [Usage and Examples](https://slurmulon.github.io/generator-collector/#/usage)

## Example

The following `node` example uses `generator-collector` and `js-coroutines` to query for the 5 best red wines in France.

```js

import { collector, promiser, each } from 'generator-collector'

import { map, sort } from 'js-coroutines' // optional, but plays nice with other coroutine libraries

async function wine () {

  const categories = ['reds', 'whites', 'sparkling', 'rose', 'dessert', 'port']

  // Create a generator-based "promiser" (coroutine) that loads and sorts a list of wines within a category

  const api = promiser(function* (category = 'reds') {

    const response = yield fetch(`https://api.sampleapis.com/wines/${category}`)

    const data = yield response.json()

    const rated = yield* sort(data, function* (a, b) {

      return yield b.rating.average - a.rating.average

    })

    const items = yield* map(rated, function* (item) {

      return yield { ...item, category }

    })

    return items

  })

  // Create a collector that reduces each result from the queried API responses into a single collection

  const load = collector(function* (query = null) {

    yield* each(query ?? categories, api)

  }, {

    // Override default insert behavior of `push.call` (now `push.apply`).

    // Enables flat reduction of each item in the API responses ([a, b, c] vs. [[a], [b], [c]]).

    insert: (store, value) => Array.prototype.push.apply(store, value)

  })

  // Invoke our data fetching collector for red wines (call `load()` instead for all wine categories)

  const query = load(['reds'])

  // Load all the red wines from the API (since we need the full list to know the "best")

  const all = await query.all()

  // Scan results for the top 5 best red wines from France

  const best = await query.take(5, (item) => item.location.startsWith('France'), true)

  return { all, best }

}

wine().then(result => {

  console.log('Loaded best red wines in France', result.best, result.all.length)

  process.exit(0)

})

```

## Contact & Support

-  Create a [GitHub issue](https://github.com/slurmulon/generator-collector/issues) for bug reports, feature requests, or questions

-   Add a ⭐️ [star on GitHub](https://github.com/slurmulon/generator-collector) or ❤️ [tweet](https://twitter.com/intent/tweet?url=https%3A%2F%2Fgithub.com%2Fslurmulon%2Fgenerator-collector&hashtags=js,generators,promises,queries) to support the project!

## License

Copyright © Erik Vavro. All rights reserved.

Licensed under the [MIT License](https://opensource.org/licenses/MIT).