npm package: @stdlib/utils-circular-buffer
Description: Circular buffer.
Author: The Stdlib Authors
Latest version: 0.2.1

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# Circular Buffer

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

> Circular buffer constructor.

<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

</section>

<!-- /.intro -->

<!-- Package usage documentation. -->

<section class="installation">

## Installation

```bash
npm install @stdlib/utils-circular-buffer
```

</section>

<section class="usage">

## Usage

```javascript
var circularBuffer = require( '@stdlib/utils-circular-buffer' );
```

#### circularBuffer( buffer )

Returns a new circular buffer instance.

```javascript
var buf = circularBuffer( 3 );
// returns <CircularBuffer>
```

The `buffer` argument may either be a integer which specifies the buffer size or an array-like object to use as the underlying buffer.

```javascript
var Float64Array = require( '@stdlib/array-float64' );

// Use a typed array as the underlying buffer:
var buf = circularBuffer( new Float64Array( 3 ) );
// returns <CircularBuffer>
```

##### circularBuffer.prototype.clear()

Clears a buffer.

```javascript
var buf = circularBuffer( 3 );
// returns <CircularBuffer>

// Add values to the buffer:
buf.push( 'foo' );
buf.push( 'bar' );
buf.push( 'beep' );

// Get the number of elements currently in the buffer:
var n = buf.count;
// returns 3

// Clear all buffer items:
buf.clear();

// Get the number of elements in the buffer:
n = buf.count;
// returns 0
```

##### circularBuffer.prototype.count

Read-only property which returns the number of elements currently in the buffer.

```javascript
var buf = circularBuffer( 3 );
// returns <CircularBuffer>

// Add values to the buffer:
buf.push( 'foo' );
buf.push( 'bar' );

// Determine how many elements are in the buffer:
var n = buf.count;
// returns 2
```

##### circularBuffer.prototype.full

Read-only property which returns a `boolean` indicating if a buffer is full.

```javascript
var buf = circularBuffer( 3 );
// returns <CircularBuffer>

// Add values to the buffer:
buf.push( 'foo' );
buf.push( 'bar' );

// Determine if the buffer is full:
var bool = buf.full;
// returns false

// Add another value to the buffer:
buf.push( 'beep' );

// Determine if the buffer is full:
bool = buf.full;
// returns true
```

##### circularBuffer.prototype.iterator( \[niters] )

Returns an iterator for iterating over a buffer. If an environment supports `Symbol.iterator`, the returned iterator is iterable.

```javascript
var buf = circularBuffer( 2 );

// Add values to the buffer:
buf.push( 'foo' );
buf.push( 'bar' );
buf.push( 'beep' );
buf.push( 'boop' );

// Create an iterator:
var it = buf.iterator();

// Iterate over the buffer...
var v = it.next().value;
// returns 'beep'

v = it.next().value;
// returns 'boop'

v = it.next().value;
// returns 'beep'

v = it.next().value;
// returns 'boop'

v = it.next().value;
// returns 'beep'
```

By default, provided a buffer is **full**, the method returns an infinite iterator. To limit the number of iterations, provide an `niters` argument.

```javascript
var buf = circularBuffer( 2 );

// Add values to the buffer:
buf.push( 'foo' );
buf.push( 'bar' );
buf.push( 'beep' );
buf.push( 'boop' );

// Create an iterator:
var it = buf.iterator( buf.length );

// Iterate over the buffer...
var v = it.next().value;
// returns 'beep'

v = it.next().value;
// returns 'boop'

var bool = it.next().done;
// returns true
```

A returned iterator does **not** iterate over partially full circular buffers.

```javascript
var buf = circularBuffer( 5 );

// Add values to the buffer:
buf.push( 'foo' );
buf.push( 'bar' );

// Create an iterator:
var it = buf.iterator();

// Determine if the buffer is full:
var bool = buf.full;
// returns false

// Iterate over the buffer...
bool = it.next().done;
// returns true
```

If iterating over a partially full circular buffer is necessary, use `buf.toArray()` and iterate over the returned array.

##### circularBuffer.prototype.length

Read-only property returning the buffer length (i.e., capacity).

```javascript
var buf = circularBuffer( [ 0, 0, 0 ] );

// Get the buffer length:
var len = buf.length;
// returns 3
```

##### circularBuffer.prototype.push( value )

Adds a value to the buffer.

```javascript
var buf = circularBuffer( 3 );

// Fill the buffer...
var v = buf.push( 'foo' );
// returns undefined

v = buf.push( 'bar' );
// returns undefined

v = buf.push( 'beep' );
// returns undefined

// Now that the buffer is full, each push will cause a value to be removed:
v = buf.push( 'boop' );
// returns 'foo'
```

When a circular buffer is empty or partially full, this method returns `undefined`. Once a circular buffer is **full**, the method returns removed values.

##### circularBuffer.prototype.toArray()

Returns an array of buffer values.

```javascript
var buf = circularBuffer( 3 );

// Add values to the buffer:
buf.push( 'foo' );
buf.push( 'bar' );
buf.push( 'beep' );
buf.push( 'boop' );

// Get an array of buffer values:
var vals = buf.toArray();
// returns [ 'bar', 'beep', 'boop' ]
```

##### circularBuffer.prototype.toJSON()

Serializes a circular buffer as JSON.

```javascript
var buf = circularBuffer( 3 );

// Add values to the buffer:
buf.push( 'foo' );
buf.push( 'bar' );
buf.push( 'beep' );
buf.push( 'boop' );

// Serialize to JSON:
var o = buf.toJSON();
// returns { 'type': 'circular-buffer', 'length': 3, 'data': [ 'bar', 'beep', 'boop' ] }
```

**Note**: `JSON.stringify()` implicitly calls this method when stringifying a circular buffer instance.

</section>

<!-- /.usage -->

<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

## Notes

-   The constructor supports array-like object `buffer` arguments which use getter and setter accessors for element access (e.g., [`Complex64Array`][@stdlib/array/complex64], [`Complex128Array`][@stdlib/array/complex128], etc).

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

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

```javascript
var circularBuffer = require( '@stdlib/utils-circular-buffer' );

// Create a circular buffer capable of holding 5 elements:
var buf = circularBuffer( 5 );
console.log( 'Buffer length: %s', buf.length );

// Continuously add values to the buffer...
var v;
var i;
for ( i = 0; i < 100; i++ ) {
    v = buf.push( i );
    console.log( 'Count: %d. Added value: %s. Removed value: %s.', buf.count, i, ( v === void 0 ) ? '(none)' : v );
}
```

</section>

<!-- /.examples -->

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<section class="references">

</section>

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<section class="related">

* * *

## See Also

-   <span class="package-name">[`@stdlib/utils-fifo`][@stdlib/utils/fifo]</span><span class="delimiter">: </span><span class="description">first-in-first-out (FIFO) queue.</span>
-   <span class="package-name">[`@stdlib/utils-stack`][@stdlib/utils/stack]</span><span class="delimiter">: </span><span class="description">stack.</span>

</section>

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* * *

## 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

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---

## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2024. The Stdlib [Authors][stdlib-authors].

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