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Merge branch 'release/1.0.0'
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Diff for: ‎.gitignore

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node_modules/
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dev/
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npm-debug.log
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yarn-error.log
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yarn.lock

Diff for: ‎README.md

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# bit-array
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# bit-array
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Save memory space by using a BitArray! Behind the scene, the library stores bits within elements of a `Uint8Array` resulting in memory space savings.
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```typescript
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// ~256 bits in memory + overhead
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const jsArray = [1, 0, 0, 1, 1, 0, 0, 0];
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// ~8 bits in memory + overhead
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const bitArray = new BitArray([1, 0, 0, 1, 1, 0, 0, 0]);
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```
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- [Size](#size)
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- [Installation](#installation)
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- [Documentation](#documentation)
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- [Release notes](#release-notes)
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## Size
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2.9 KB
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## Installation
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**via npm**
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`npm install bit-array`
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**via yarn**
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`yarn add bit-array`
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**dev**
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`npm install`
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`yarn install`
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`yarn start`
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## Documentation
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#### Usage
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```typescript
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import BitArray from "../lib/bit-array";
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const arr = new BitArray([0, 1, 0]);
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arr.pushAll([1, 1, 1]);
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// 0, 1, 0, 1, 1, 1
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arr.push(0);
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// 0, 1, 0, 1, 1, 1, 0
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arr.atIndex(0);
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// 0
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arr.atIndexRange(0, 3);
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// 0, 1, 0
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console.log(arr.size)
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// 7
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```
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#### Methods
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Method | Description
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--- | ---
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**`pushAll(values: Array<bit>)`** | Pushes a an array of bits onto the array
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**`push(value: bit)`** | Pushes a single bit onto the array
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**`atIndex(index: number)`** | Gets the bit at a given index.
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**`atIndexRange(index: number, count: number)`** | Gets count bits at a given index
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#### Properties
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Property | Description
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--- | ---
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**`size`** | Gets the size of the array
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## Release notes
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### 1.0.0
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Initial release
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- `pushAll(values: Array<bit>)`
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- `push(value: bit)`
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- `atIndex(index: number)`
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- `atIndexRange(index: number, count: number)`
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- `size`
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Diff for: ‎package.json

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{
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"name": "bit-array",
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"description": "Bit array implementation in javascript",
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"version": "0.1.0",
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"repository": {
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"type": "git",
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"url": "https://github.com/Bubblesphere/bit-array.git"
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},
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"keywords": [
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"bit",
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"array",
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"typescript",
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"javascript"
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],
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"author": "Déric Dallaire",
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"license": "MIT",
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"bugs": {
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"url": "https://github.com/Bubblesphere/bit-array/issues"
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},
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"homepage": "https://github.com/Bubblesphere/bit-array",
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"devDependencies": {
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"babel-preset-es2015": "^6.24.1",
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"clean-webpack-plugin": "^0.1.19",
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"copy-webpack-plugin": "^4.5.1",
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"ts-loader": "^4.1.0",
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"typescript": "^2.7.2",
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"webpack": "^4.1.1",
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"webpack-bundle-analyzer": "^2.11.1",
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"webpack-cli": "^2.0.12",
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"webpack-dev-server": "^3.1.1",
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"webpack-merge": "^4.1.2"
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},
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"scripts": {
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"start": "webpack-dev-server --open-page dev/index.html --config webpack.dev.js --mode development ",
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"build": "webpack --config webpack.prod.js --mode production"
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}
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}

Diff for: ‎src/demo/index.html

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<html>
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<head>
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<title>bit-array</title>
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</head>
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<body>
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<h1>Hello world!</h1>
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<p>Look up the console to show the results</p>
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<xmp>
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import BitArray from "../lib/bit-array";
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const arr = new BitArray([0, 1, 0]);
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arr.pushAll([1, 1, 1]);
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// 0, 1, 0, 1, 1, 1
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arr.push(0);
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// 0, 1, 0, 1, 1, 1, 0
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arr.atIndex(0);
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// 0
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arr.atIndexRange(0, 3);
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// 0, 1, 0
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console.log(arr.size)
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// 7
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</xmp>
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<script src="common-bundle.js"></script>
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<script src="index-bundle.js"></script>
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</body>
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</html>

Diff for: ‎src/demo/index.ts

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import BitArray from "../lib/bit-array";
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const arr = new BitArray([0, 1, 0]);
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arr.pushAll([1, 1, 1]);
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console.log(arr.atIndexRange(0, arr.size));
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// 0, 1, 0, 1, 1, 1
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arr.push(0);
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console.log(arr.atIndexRange(0, arr.size));
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// 0, 1, 0, 1, 1, 1, 0
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arr.atIndex(0);
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console.log(arr.atIndex(0));
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// 0
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arr.atIndexRange(0, 3);
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console.log(arr.atIndexRange(0, 3));
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// 0, 1, 0
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console.log(arr.size)
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// 7

Diff for: ‎src/lib/bit-array.ts

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export type bit = 0 | 1;
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type byte = number;
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export default class BitArray {
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private _array: Uint8Array;
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private _size: number;
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private _pushedSize: number;
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private _pointer: number;
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private _bitPerIndex: number = 8;
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/**
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* Creates a bitArray
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* @param values The bits to push onto the array
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*/
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constructor(values: Array<bit>) {
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this._pushedSize = 0;
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this._size = values.length;
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this._array = new Uint8Array(Math.ceil(this._size/this._bitPerIndex));
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this._pointer = 0;
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this.pushAll(values);
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}
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/**
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* Gets the size of the array
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*/
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public get size() {
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return this._pushedSize;
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}
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/**
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* Pushes a single bit onto the array
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* @param value The bit to push onto the array
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*/
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public push(value: bit) {
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if (this._pointer == this._size) {
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this._increaseArraySize();
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}
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// create a mask for current index.
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const mask = this._createMask(this._pointer);
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// compare the array with the mask. A value different than 0 means the target bit is set
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if (this._matchesMask(mask, this._array[this._arrayIndex(this._pointer)])) {
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// bit is set in array. Should we toggle it?
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if (value === 0) {
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this._array[this._arrayIndex(this._pointer)] ^= mask;
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}
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} else {
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// bit is unset in array. Sould we toggle it?
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if (value === 1) {
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this._array[this._arrayIndex(this._pointer)] ^= mask;
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}
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}
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// increment pointer for next push
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this._pushedSize++;
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this._pointer++;
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}
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/**
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* Pushes a an array of bits onto the array
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* @param values The bits to push onto the array
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*/
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public pushAll(values: Array<bit>) {
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// TODO: Improve performance
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values.forEach((value) => {
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this.push(value);
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});
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}
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/**
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* Gets the bit at a given index
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* @param index The index of the bit to return
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*/
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public atIndex(index: number): bit {
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if (index > this._pushedSize) {
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throw `Index (${index}) exceeds the size of the bit array (${this._pushedSize})`;
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}
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const mask = this._createMask(index);
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return this._matchesMask(mask, this._array[this._arrayIndex(index)]) ? 1 : 0;
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}
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/**
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* Gets count bits at a given index
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* @param index The index of the first bit to return
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* @param count The amount of bits to fetch starting at the index
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*/
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public atIndexRange(index: number, count: number): bit[] {
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if (index + count - 1 > this._pushedSize) {
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throw `Index (${index}) exceeds the size of the bit array (${this._pushedSize})`;
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}
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const values: bit[] = [];
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for (let i = 0; i < count; i++) {
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const mask = this._createMask(index + i);
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values.push(this._matchesMask(mask, this._array[this._arrayIndex(index + i)]) ? 1 : 0);
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}
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return values;
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}
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// Checks whether a value has a bit of 1 at the mask position
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private _matchesMask(mask: byte, value: byte) {
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// returns true if bit is set
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return (mask & value) != 0;
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}
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// Creates a mask for a given index
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private _createMask(index: number): byte {
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// supposing the index is 2, the created mask is
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// 00100000
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return 1 << (this._bitPerIndex - 1) - this._arrayIndexOffset(index);
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}
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// Gets the Uint8Array index
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private _arrayIndex(index: number) {
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return Math.floor(index / this._bitPerIndex);
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}
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// Gets the offset within the Uint8Array
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private _arrayIndexOffset(index: number) {
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return index % this._bitPerIndex;
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}
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private _increaseArraySize() {
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this._size = this._size * 2;
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const tempArr = this._array.slice();
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this._array = new Uint8Array(Math.ceil(this._size/this._bitPerIndex));
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this._array = tempArr.slice();
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}
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};

Diff for: ‎tsconfig.json

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{
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"compilerOptions": {
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"module": "esnext",
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"noImplicitAny": true,
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"removeComments": true,
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"preserveConstEnums": true,
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"sourceMap": true,
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"target": "es5"
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},
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"include": [
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"src/**/*"
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],
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"exclude": [
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"node_modules",
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"**/*.test.ts"
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]
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}

Diff for: ‎webpack.common.js

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var path = require("path");
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const webpack = require('webpack');
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const CleanWebpackPlugin = require('clean-webpack-plugin');
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const CopyWebpackPlugin = require('copy-webpack-plugin');
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module.exports = {
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target: 'web',
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resolve: {
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extensions: ['.ts', '.tsx', '.js']
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},
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entry: {
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index: "./src/demo/index.ts"
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},
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output: {
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filename: "[name]-bundle.js",
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path: path.resolve(__dirname, "dev"),
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publicPath: "/dev/"
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},
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// Demos use the same library, bundle the code in common into a diff file
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optimization: {
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splitChunks: {
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chunks: "all",
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minSize: 1000,
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name: "common"
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}
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},
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plugins: [
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new CopyWebpackPlugin([{
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from: 'src/demo/*.html',
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flatten: true
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}])
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],
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module: {
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rules: [
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{
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test: /\.tsx?$/,
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loader: "ts-loader",
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}
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]
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}
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};

Diff for: ‎webpack.dev.js

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const merge = require('webpack-merge');
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const common = require('./webpack.common.js');
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module.exports = merge(common, {
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devtool: 'inline-source-map',
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devServer: {
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stats: {
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assets: false,
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hash: false,
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chunks: false,
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errors: true,
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errorDetails: true,
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},
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overlay: true,
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}
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});

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