time-to-botec/js/node_modules/@stdlib/streams/node/from-iterator/README.md

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# Iterator Stream

> Create a [readable stream][readable-stream] from an [iterator][mdn-iterator-protocol].

<section class="usage">

## Usage

```javascript
var iteratorStream = require( '@stdlib/streams/node/from-iterator' );
```

<a name="iterator-stream"></a>

#### iteratorStream( iterator\[, options] )

Returns a [readable stream][readable-stream] from an [iterator][mdn-iterator-protocol].

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

var iStream;
var stream;

function log( chunk, idx ) {
    console.log( chunk.toString() );
    if ( idx === 10 ) {
        stream.destroy();
    }
}

stream = iteratorStream( randu() );
iStream = inspectStream( log );

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 iteration.
-   **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].

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

```javascript
var randu = require( '@stdlib/random/iter/randu' );

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

var stream = iteratorStream( randu(), opts );
```

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

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

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

var it = randu({
    'iter': 10
});

var stream = iteratorStream( it, {
    'sep': ','
});

var iStream = inspectStream( log );

stream.pipe( iStream );
```

By default, when not operating in [objectMode][object-mode], a returned [stream][stream] serializes iterated 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' );
var randu = require( '@stdlib/random/iter/randu' );

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

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

var it = randu({
    'iter': 10
});

var stream = iteratorStream( it, {
    'serialize': serialize
});

var iStream = inspectStream( log );

stream.pipe( iStream );
```

* * *

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

Returns a `function` for creating [readable streams][readable-stream] from [iterators][mdn-iterator-protocol].

```javascript
var randu = require( '@stdlib/random/iter/randu' );

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

var createStream = iteratorStream.factory( opts );

var stream1 = createStream( randu() );
var stream2 = createStream( randu() );
// ...
```

The method accepts the same `options` as [`iteratorStream()`](#iterator-stream).

* * *

#### iteratorStream.objectMode( iterator\[, 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' );
var randu = require( '@stdlib/random/iter/randu' );

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

var opts = {
    'iter': 10
};
var stream = iteratorStream.objectMode( randu( opts ) );

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

stream.pipe( iStream );
```

This method accepts the same `options` as [`iteratorStream()`](#iterator-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 [iterator][mdn-iterator-protocol] generates `null` values (e.g., as a means to encode missing values), the stream will prematurely end. Consider an alternative encoding or explicitly map `null` values to a different value by wrapping the provided [iterator][mdn-iterator-protocol] with another [iterator][mdn-iterator-protocol].
-   In binary mode, if an [iterator][mdn-iterator-protocol] generates `undefined` values, the stream will emit an error. Consider providing a custom serialization function or explicitly map `undefined` values to a different value by wrapping the provided [iterator][mdn-iterator-protocol] with another [iterator][mdn-iterator-protocol].

</section>

<!-- /.notes -->

* * *

<section class="examples">

## Examples

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

```javascript
var inspectStream = require( '@stdlib/streams/node/inspect-sink' );
var randu = require( '@stdlib/random/iter/randu' );
var iteratorStream = require( '@stdlib/streams/node/from-iterator' );

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

// Create an iterator which generates uniformly distributed pseudorandom numbers:
var opts = {
    'iter': 10
};
var it = randu( opts );

// Convert the iterator to a stream:
opts = {
    'objectMode': true
};
var stream = iteratorStream( it, 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 class="links">

[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

[mdn-iterator-protocol]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#The_iterator_protocol

</section>

<!-- /.links -->