npm package: @stdlib/streams-node-from-circular-array
Description: Create a readable stream from a circular array-like object.
Author: The Stdlib Authors
Latest version: 0.2.3

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  <summary>
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# Circular Array Stream

[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] <!-- [![dependencies][dependencies-image]][dependencies-url] -->

> Create a [readable stream][readable-stream] from a circular array-like object.

<section class="installation">

## Installation

```bash
npm install @stdlib/streams-node-from-circular-array
```

</section>

<section class="usage">

## Usage

```javascript
var circularArrayStream = require( '@stdlib/streams-node-from-circular-array' );
```

<a name="circular-array-stream"></a>

#### circularArrayStream( src\[, options] )

Returns a [readable stream][readable-stream] from an array-like `object` which repeatedly iterates over a provided value's elements.

```javascript
var inspectStream = require( '@stdlib/streams-node-inspect-sink' );

var iStream;
var stream;
var count;

function log( chunk ) {
    console.log( chunk.toString() );
    count += 1;
    if ( count === 20 ) {
        stream.destroy();
    }
}

stream = circularArrayStream( [ 1, 2, 3, 4 ] );
iStream = inspectStream( log );

count = 0;
stream.pipe( iStream );
```

The function accepts the following `options`:

-   **objectMode**: specifies whether a [stream][stream] should operate in [objectMode][object-mode]. Default: `false`.
-   **encoding**: specifies how `Buffer` objects should be decoded to `strings`. Default: `null`.
-   **highWaterMark**: specifies the maximum number of bytes to store in an internal buffer before pausing streaming.
-   **sep**: separator used to join streamed data. This option is only applicable when a stream is **not** in [objectMode][object-mode]. Default: `'\n'`.
-   **serialize**: custom serialization function. This option is only applicable when a stream is **not** in [objectMode][object-mode].
-   **iter**: number of iterations. Default: `1e308`.
-   **dir**: iteration direction. If set to `-1`, the stream iterates over elements from right-to-left. Default: `1`.

To set [stream][stream] `options`,

```javascript
var opts = {
    'objectMode': true,
    'encoding': 'utf8',
    'highWaterMark': 64
};

var stream = circularArrayStream( [ 1, 2, 3, 4 ], opts );
```

By default, the returned [stream][stream] is an infinite stream (i.e., never ends). To limit the number of streamed values, set the `iter` option.

```javascript
var inspectStream = require( '@stdlib/streams-node-inspect-sink' );

function log( chunk ) {
    console.log( chunk.toString() );
}

var opts = {
    'iter': 10
};
var stream = circularArrayStream( [ 1, 2, 3, 4 ], opts );
var iStream = inspectStream( log );

stream.pipe( iStream );
```

By default, when not operating in [objectMode][object-mode], a returned [stream][stream] delineates individual values using a newline character. To specify an alternative separator, set the `sep` option.

```javascript
var inspectStream = require( '@stdlib/streams-node-inspect-sink' );

function log( chunk ) {
    console.log( chunk.toString() );
}

var stream = circularArrayStream( [ 1, 2, 3, 4 ], {
    'sep': ',',
    'iter': 10
});

var iStream = inspectStream( log );

stream.pipe( iStream );
```

By default, when not operating in [objectMode][object-mode], a returned [stream][stream] serializes values as JSON strings. To specify custom serialization behavior (either to a `string` or `Buffer`), set the `serialize` option.

```javascript
var inspectStream = require( '@stdlib/streams-node-inspect-sink' );

function serialize( v ) {
    return 'v::' + v.toString();
}

function log( chunk ) {
    console.log( chunk.toString() );
}

var stream = circularArrayStream( [ 1, 2, 3, 4 ], {
    'serialize': serialize,
    'iter': 10
});

var iStream = inspectStream( log );

stream.pipe( iStream );
```

* * *

#### circularArrayStream.factory( \[options] )

Returns a `function` for creating [readable streams][readable-stream] from array-like objects.

```javascript
var opts = {
    'objectMode': true,
    'encoding': 'utf8',
    'highWaterMark': 64
};

var createStream = circularArrayStream.factory( opts );

var stream1 = createStream( [ 1, 2, 3, 4 ] );
var stream2 = createStream( [ 5, 6, 7, 8 ] );
// ...
```

The method accepts the same `options` as [`circularArrayStream()`](#circular-array-stream).

* * *

#### circularArrayStream.objectMode( src\[, options] )

This method is a convenience function to create [streams][stream] which **always** operate in [objectMode][object-mode].

```javascript
var inspectStream = require( '@stdlib/streams-node-inspect-sink' );

function log( v ) {
    console.log( v );
}

var opts = {
    'iter': 10
};
var stream = circularArrayStream.objectMode( [ 1, 2, 3, 4 ], opts );

opts = {
    'objectMode': true
};
var iStream = inspectStream( opts, log );

stream.pipe( iStream );
```

This method accepts the same `options` as [`circularArrayStream()`](#circular-array-stream); however, the method will **always** override the [`objectMode`][object-mode] option in `options`.

</section>

<!-- /.usage -->

* * *

<section class="notes">

## Notes

-   In [`objectMode`][object-mode], `null` is a reserved value. If an `array` contains `null` values (e.g., as a means to encode missing values), the stream will prematurely end. Consider an alternative encoding or filter `null` values prior to invocation.
-   In binary mode, if an `array` contains `undefined` values, the stream will emit an error. Consider providing a custom serialization function or filtering `undefined` values prior to invocation.

</section>

<!-- /.notes -->

* * *

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var inspectStream = require( '@stdlib/streams-node-inspect-sink' );
var randu = require( '@stdlib/random-base-randu' );
var Float64Array = require( '@stdlib/array-float64' );
var circularArrayStream = require( '@stdlib/streams-node-from-circular-array' );

function log( v ) {
    console.log( v.toString() );
}

// Create an array containing uniformly distributed pseudorandom numbers:
var arr = new Float64Array( 10 );

var i;
for ( i = 0; i < arr.length; i++ ) {
    arr[ i ] = randu();
}

// Convert the array to a stream:
var opts = {
    'objectMode': true,
    'iter': arr.length * 3
};
var stream = circularArrayStream( arr, opts );

// Create a writable stream for inspecting stream data:
opts = {
    'objectMode': true
};
var iStream = inspectStream( opts, log );

// Begin data flow:
stream.pipe( iStream );
```

</section>

<!-- /.examples -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

* * *

## See Also

-   <span class="package-name">[`@stdlib/streams-node/from-array`][@stdlib/streams/node/from-array]</span><span class="delimiter">: </span><span class="description">create a readable stream from an array-like object.</span>
-   <span class="package-name">[`@stdlib/streams-node/from-iterator`][@stdlib/streams/node/from-iterator]</span><span class="delimiter">: </span><span class="description">create a readable stream from an iterator.</span>
-   <span class="package-name">[`@stdlib/streams-node/from-strided-array`][@stdlib/streams/node/from-strided-array]</span><span class="delimiter">: </span><span class="description">create a readable stream from a strided array-like object.</span>

</section>

<!-- /.related -->

<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->


<section class="main-repo" >

* * *

## Notice

This package is part of [stdlib][stdlib], a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib].

#### Community

[![Chat][chat-image]][chat-url]

---

## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

</section>

<!-- /.stdlib -->

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[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/streams-node-from-circular-array/main/LICENSE

[stream]: https://nodejs.org/api/stream.html

[object-mode]: https://nodejs.org/api/stream.html#stream_object_mode

[readable-stream]: https://nodejs.org/api/stream.html

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