165 lines
3.2 KiB
Markdown
165 lines
3.2 KiB
Markdown
# hoopy
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[](https://gitlab.com/philbooth/hoopy/pipelines)
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[](https://www.npmjs.com/package/hoopy)
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[](https://www.npmjs.com/package/hoopy)
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[](https://opensource.org/licenses/MIT)
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Like an array, but rounder.
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* [Huh?](#huh)
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* [What's it useful for?](#whats-it-useful-for)
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* [How do I install it?](#how-do-i-install-it)
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* [How do I use it?](#how-do-i-use-it)
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* [Loading the library](#loading-the-library)
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* [Creating arrays](#creating-arrays)
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* [Accessing array items](#accessing-array-items)
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* [Growing the array](#growing-the-array)
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* [Is there a change log?](#is-there-a-change-log)
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* [How do I set up the dev environment?](#how-do-i-set-up-the-dev-environment)
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* [What license is it released under?](#what-license-is-it-released-under)
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## Huh?
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Hoopy is a circular array
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data type.
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It extends `Array`
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so that out-of-bounds indices
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wrap back round
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to the start of the array
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(or if they're negative indices,
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they wrap back round
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to the end of the array).
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## What's it useful for?
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If you want a fixed-length buffer
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for streamed I/O,
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Hoopy can do that for you.
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## How do I install it?
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Via `npm`:
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```
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npm i hoopy --save
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```
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Or if you just want the git repo:
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```
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git clone git@gitlab.com:philbooth/hoopy.git
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```
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## How do I use it?
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### Loading the library
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```js
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const Hoopy = require('hoopy');
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```
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### Creating arrays
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```js
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const hoopy = new Hoopy(10);
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assert(Array.isArray(hoopy));
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```
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You must pass
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a `size` argument
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to the `Hoopy` constructor,
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otherwise it will throw.
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### Accessing array items
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```js
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for (let i = 0; i < hoopy.length; ++i) {
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hoopy[i] = i;
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console.log(hoopy[i]);
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}
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```
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You can read and write array items
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using square brackets for indexing
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as you would with a normal array.
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However, if you write to
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an out-of-bounds index,
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it will not increase
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the length of the array.
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Instead the index is applied
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modulo the array length,
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wrapping back round to the start.
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Negative indices work in reverse,
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wrapping back round to the end
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of the array.
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The methods
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`push`, `pop`, `shift` and `unshift`
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will throw if called.
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Future versions of the library
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may implement sane behaviour
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for them.
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All of the other `Array` methods
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work normally.
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### Growing the array
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```js
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hoopy.grow(50);
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```
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The `grow` method
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adds items to the array.
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It takes one argument,
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which is the number
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of items to grow the array by.
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The new length of the array
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will be the old length
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plus the number you pass to `grow`.
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If the current state of the array
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includes overflowed indices,
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`grow` will take care
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to move those items
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in to the freshly-created
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available space,
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so that the correct order is maintained
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for your data.
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The caller is responsible
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for ensuring they don't overwrite
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unprocessed items.
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If you need to increase
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the size of the array,
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you must call `grow`.
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## Is there a change log?
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[Yes](CHANGELOG.md).
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## How do I set up the dev environment?
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To install the dependencies:
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```
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npm i
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```
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To run the tests:
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```
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npm t
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```
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To lint the code:
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```
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npm run lint
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```
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## What license is it released under?
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[MIT](LICENSE).
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