basant307/AI_Governance_Project

1smart-buffer  [![Build Status](https://travis-ci.org/JoshGlazebrook/smart-buffer.svg?branch=master)](https://travis-ci.org/JoshGlazebrook/smart-buffer)  [![Coverage Status](https://coveralls.io/repos/github/JoshGlazebrook/smart-buffer/badge.svg?branch=master)](https://coveralls.io/github/JoshGlazebrook/smart-buffer?branch=master)2=============3 4smart-buffer is a light Buffer wrapper that takes away the need to keep track of what position to read and write data to and from the underlying Buffer. It also adds null terminating string operations and **grows** as you add more data.5 6![stats](https://nodei.co/npm/smart-buffer.png?downloads=true&downloadRank=true&stars=true "stats")7 8### What it's useful for:9 10I created smart-buffer because I wanted to simplify the process of using Buffer for building and reading network packets to send over a socket. Rather than having to keep track of which position I need to write a UInt16 to after adding a string of variable length, I simply don't have to.11 12Key Features:13* Proxies all of the Buffer write and read functions.14* Keeps track of read and write positions for you.15* Grows the internal Buffer as you add data to it. 16* Useful string operations. (Null terminating strings)17* Allows for inserting values at specific points in the internal Buffer.18* Built in TypeScript19* Type Definitions Provided20 21Requirements:22* Node v4.0+ is supported at this time.  (Versions prior to 2.0 will work on node 0.10)23 24 25#### Note:26smart-buffer can be used for writing to an underlying buffer as well as reading from it. It however does not function correctly if you're mixing both read and write operations with each other.27 28## Breaking Changes with 2.029The latest version (2.0+) is written in TypeScript, and are compiled to ES6 Javascript. This means the earliest Node.js it supports will be 4.x (in strict mode.) If you're using version 6 and above it will work without any issues. From an API standpoint, 2.0 is backwards compatible. The only difference is SmartBuffer is not exported directly as the root module.30 31## Breaking Changes with 3.032Starting with 3.0, if any of the readIntXXXX() methods are called and the requested data is larger than the bounds of the internally managed valid buffer data, an exception will now be thrown.33 34## Installing:35 36`npm install smart-buffer`37 38or39 40`yarn add smart-buffer`41 42Note: The published NPM package includes the built javascript library. 43If you cloned this repo and wish to build the library manually use:44 45`tsc -p ./`46 47## Using smart-buffer48 49### Example50 51Say you were building a packet that had to conform to the following protocol:52 53`[PacketType:2][PacketLength:2][Data:XX]`54 55To build this packet using the vanilla Buffer class, you would have to count up the length of the data payload beforehand. You would also need to keep track of the current "cursor" position in your Buffer so you write everything in the right places. With smart-buffer you don't have to do either of those things.56 57```javascript58// 1.x (javascript)59var SmartBuffer = require('smart-buffer');60 61// 1.x (typescript)62import SmartBuffer = require('smart-buffer');63 64// 2.x+ (javascript)65const SmartBuffer = require('smart-buffer').SmartBuffer;66 67// 2.x+ (typescript)68import { SmartBuffer, SmartBufferOptions} from 'smart-buffer';69 70function createLoginPacket(username, password, age, country) {71    let packet = new SmartBuffer();72    packet.writeUInt16LE(0x0060); // Login Packet Type/ID73    packet.writeStringNT(username);74    packet.writeStringNT(password);75    packet.writeUInt8(age);76    packet.writeStringNT(country);77    packet.writeUInt16LE(packet.length - 2, 2);78    79    return packet.toBuffer();80}81```82With the above function, you now can do this:83```javascript84let login = createLoginPacket("Josh", "secret123", 22, "United States");85 86// <Buffer 60 00 1e 00 4a 6f 73 68 00 73 65 63 72 65 74 31 32 33 00 16 55 6e 69 74 65 64 20 53 74 61 74 65 73 00>87```88Notice that the `[PacketLength:2]` part of the packet was inserted after we had added everything else, and as shown in the Buffer dump above, is in the correct location along with everything else.89 90Reading back the packet we created above is just as easy:91```javascript92 93let reader = SmartBuffer.fromBuffer(login);94 95let logininfo = {96    packetType: reader.readUInt16LE(),97    packetLength: reader.readUInt16LE(),98    username: reader.readStringNT(),99    password: reader.readStringNT(),100    age: reader.readUInt8(),101    country: reader.readStringNT()102};103 104/*105{ 106    packetType: 96, (0x0060)107    packetLength: 30,108    username: 'Josh',109    password: 'secret123',110    age: 22,111    country: 'United States' 112};113*/114```115 116# Api Reference:117 118### Constructing a smart-buffer119 120smart-buffer has a few different ways to construct an instance. Starting with version 2.0, the following factory methods are preffered.121 122```javascript123let SmartBuffer = require('smart-buffer');124 125// Creating SmartBuffer from existing Buffer126let buff = SmartBuffer.fromBuffer(buffer); // Creates instance from buffer. (Uses default utf8 encoding)127let buff = SmartBuffer.fromBuffer(buffer, 'ascii'); // Creates instance from buffer with ascii encoding for Strings. 128 129// Creating SmartBuffer with specified internal Buffer size.130let buff = SmartBuffer.fromSize(1024); // Creates instance with internal Buffer size of 1024.131let buff = SmartBuffer.fromSize(1024, 'utf8'); // Creates instance with intenral Buffer size of 1024, and utf8 encoding. 132 133// Creating SmartBuffer with options object. This one specifies size and encoding.134let buff = SmartBuffer.fromOptions({135    size: 1024,136    encoding: 'ascii'137});138 139// Creating SmartBuffer with options object. This one specified an existing Buffer.140let buff = SmartBuffer.fromOptions({141    buff: buffer142});143 144// Just want a regular SmartBuffer with all default options?145let buff = new SmartBuffer();146```147 148## Backwards Compatibility:149 150All constructors used prior to 2.0 still are supported. However it's not recommended to use these.151 152```javascript153let writer = new SmartBuffer();               // Defaults to utf8, 4096 length internal Buffer.154let writer = new SmartBuffer(1024);           // Defaults to utf8, 1024 length internal Buffer.155let writer = new SmartBuffer('ascii');         // Sets to ascii encoding, 4096 length internal buffer.156let writer = new SmartBuffer(1024, 'ascii');  // Sets to ascii encoding, 1024 length internal buffer.157```158 159## Reading Data160 161smart-buffer supports all of the common read functions you will find in the vanilla Buffer class. The only difference is, you do not need to specify which location to start reading from. This is possible because as you read data out of a smart-buffer, it automatically progresses an internal read offset/position to know where to pick up from on the next read.162 163## Reading Numeric Values164 165When numeric values, you simply need to call the function you want, and the data is returned.166 167Supported Operations:168* readInt8169* readInt16BE170* readInt16LE171* readInt32BE172* readInt32LE173* readBigInt64LE174* readBigInt64BE175* readUInt8176* readUInt16BE177* readUInt16LE178* readUInt32BE179* readUInt32LE180* readBigUInt64LE181* readBigUInt64BE182* readFloatBE183* readFloatLE184* readDoubleBE185* readDoubleLE186 187```javascript188let reader = new SmartBuffer(somebuffer);189let num = reader.readInt8();190```191 192## Reading String Values193 194When reading String values, you can either choose to read a null terminated string, or a string of a specified length.195 196### SmartBuffer.readStringNT( [encoding] )197> `String` **String encoding to use**  - Defaults to the encoding set in the constructor. 198 199returns `String`200 201> Note: When readStringNT is called and there is no null character found, smart-buffer will read to the end of the internal Buffer.202 203### SmartBuffer.readString( [length] )204### SmartBuffer.readString( [encoding] )205### SmartBuffer.readString( [length], [encoding] )206> `Number` **Length of the string to read**207 208> `String` **String encoding to use** - Defaults to the encoding set in the constructor, or utf8.209 210returns `String`211 212> Note: When readString is called without a specified length, smart-buffer will read to the end of the internal Buffer.213 214 215 216## Reading Buffer Values217 218### SmartBuffer.readBuffer( length )219> `Number` **Length of data to read into a Buffer**220 221returns `Buffer`222 223> Note: This function uses `slice` to retrieve the Buffer.224 225 226### SmartBuffer.readBufferNT()227 228returns `Buffer`229 230> Note: This reads the next sequence of bytes in the buffer until a null (0x00) value is found. (Null terminated buffer)231> Note: This function uses `slice` to retrieve the Buffer.232 233 234## Writing Data235 236smart-buffer supports all of the common write functions you will find in the vanilla Buffer class. The only difference is, you do not need to specify which location to write to in your Buffer by default. You do however have the option of **inserting** a piece of data into your smart-buffer at a given location. 237 238 239## Writing Numeric Values240 241 242For numeric values, you simply need to call the function you want, and the data is written at the end of the internal Buffer's current write position. You can specify a offset/position to **insert** the given value at, but keep in mind this does not override data at the given position. This feature also does not work properly when inserting a value beyond the current internal length of the smart-buffer (length being the .length property of the smart-buffer instance you're writing to)243 244Supported Operations:245* writeInt8246* writeInt16BE247* writeInt16LE248* writeInt32BE249* writeInt32LE250* writeBigInt64BE251* writeBigInt64LE252* writeUInt8253* writeUInt16BE254* writeUInt16LE255* writeUInt32BE256* writeUInt32LE257* writeBigUInt64BE258* writeBigUInt64LE259* writeFloatBE260* writeFloatLE261* writeDoubleBE262* writeDoubleLE263 264The following signature is the same for all the above functions:265 266### SmartBuffer.writeInt8( value, [offset] )267> `Number` **A valid Int8 number**268 269> `Number` **The position to insert this value at** 270 271returns this 272 273> Note: All write operations return `this` to allow for chaining.274 275## Writing String Values276 277When reading String values, you can either choose to write a null terminated string, or a non null terminated string.278 279### SmartBuffer.writeStringNT( value, [offset], [encoding] )280### SmartBuffer.writeStringNT( value, [offset] )281### SmartBuffer.writeStringNT( value, [encoding] )282> `String` **String value to write**283 284> `Number` **The position to insert this String at**285 286> `String` **The String encoding to use.** - Defaults to the encoding set in the constructor, or utf8.287 288returns this289 290### SmartBuffer.writeString( value, [offset], [encoding] )291### SmartBuffer.writeString( value, [offset] )292### SmartBuffer.writeString( value, [encoding] )293> `String` **String value to write**294 295> `Number` **The position to insert this String at**296 297> `String` **The String encoding to use** - Defaults to the encoding set in the constructor, or utf8.298 299returns this300 301 302## Writing Buffer Values303 304### SmartBuffer.writeBuffer( value, [offset] )305> `Buffer` **Buffer value to write**306 307> `Number` **The position to insert this Buffer's content at**308 309returns this310 311### SmartBuffer.writeBufferNT( value, [offset] )312> `Buffer` **Buffer value to write**313 314> `Number` **The position to insert this Buffer's content at**315 316returns this317 318 319## Utility Functions320 321### SmartBuffer.clear()322Resets the SmartBuffer to its default state where it can be reused for reading or writing.323 324### SmartBuffer.remaining()325 326returns `Number` The amount of data left to read based on the current read Position.327 328### SmartBuffer.skip( value )329> `Number` **The amount of bytes to skip ahead**330 331Skips the read position ahead by the given value.332 333returns this334 335### SmartBuffer.rewind( value )336> `Number` **The amount of bytes to reward backwards**337 338Rewinds the read position backwards by the given value.339 340returns this341 342### SmartBuffer.moveTo( position )343> `Number` **The point to skip the read position to**344 345Moves the read position to the given point.346returns this347 348### SmartBuffer.toBuffer()349 350returns `Buffer` A Buffer containing the contents of the internal Buffer.351 352> Note: This uses the slice function.353 354### SmartBuffer.toString( [encoding] )355> `String` **The String encoding to use** - Defaults to the encoding set in the constructor, or utf8.356 357returns `String` The internal Buffer in String representation.358 359## Properties360 361### SmartBuffer.length362 363returns `Number` **The length of the data that is being tracked in the internal Buffer** - Does NOT return the absolute length of the internal Buffer being written to.364 365## License366 367This work is licensed under the [MIT license](http://en.wikipedia.org/wiki/MIT_License).