Began implementing Buffer static side

src/buffer.ts

@@ -3,6 +3,22 @@ import type { Buffer as NodeBuffer } from 'buffer';
 export class Buffer extends Uint8Array implements NodeBuffer {
 	protected view = new DataView(this.buffer, this.byteOffset, this.byteLength);
 
+	/* constructor(str: string, encoding?: BufferEncoding);
+	constructor(size: number);
+	constructor(array: Uint8Array | ArrayBufferLike | readonly any[]);
+	constructor(dataOrLength: readonly any[] | string | number | Uint8Array | ArrayBufferLike, encoding?: BufferEncoding) */
+
+	constructor(input: string | ArrayBufferLike | Uint8Array | number, encoding?: BufferEncoding) {
+		if (typeof input === 'number') {
+			super(input);
+		} else if (typeof input === 'string') {
+			super(encode(input, encoding || 'utf8'));
+		} else {
+			super(input);
+		}
+		this.view = new DataView(this.buffer, this.byteOffset, this.byteLength);
+	}
+
 	write(string: string, offset?: number | BufferEncoding, length?: number | BufferEncoding, encoding?: BufferEncoding): number {
 		let actualOffset = 0;
 		let actualLength = this.length;
@@ -383,10 +399,180 @@ export class Buffer extends Uint8Array implements NodeBuffer {
 		this.view.setFloat64(offset, value, false);
 		return offset + 8;
 	}
+
+	/* from(arrayBuffer: WithImplicitCoercion<ArrayBufferLike>, byteOffset?: number, length?: number): Buffer;
+	from(data: WithImplicitCoercion<Uint8Array | readonly number[] | string>): Buffer;
+	from(str: WithImplicitCoercion<string> | { [Symbol.toPrimitive](hint: 'string'): string }, encoding?: BufferEncoding): Buffer; */
+	from(
+		value: WithImplicitCoercion<ArrayBufferLike | Uint8Array | string | readonly number[]> | { [Symbol.toPrimitive](hint: 'string'): string },
+		encoding?: number | BufferEncoding,
+		length?: number
+	): Buffer {
+		if (typeof value === 'string') return new Buffer(encode(value, encoding || 'utf8'));
+		if (value instanceof ArrayBuffer || value instanceof SharedArrayBuffer) return new Buffer(new Uint8Array(value));
+		if (Array.isArray(value)) return new Buffer(new Uint8Array(value));
+		return new Buffer(value);
+	}
+
+	// alloc(size: number, fill?: string | Uint8Array | number, encoding?: BufferEncoding): Buffer
+	static alloc(size: number, fill?: string | number | Uint8Array, encoding: BufferEncoding = 'utf8'): Buffer {
+		const buffer = new Buffer(size);
+		if (fill === undefined) return buffer;
+
+		if (typeof fill === 'string') {
+			buffer.fill(encode(fill, encoding));
+		} else if (typeof fill === 'number') {
+			buffer.fill(fill);
+		} else {
+			buffer.set(fill);
+		}
+
+		return buffer;
+	}
+
+	// allocUnsafe(size: number): Buffer
+	static allocUnsafe(size: number): Buffer {
+		return new Buffer(size);
+	}
+
+	// concat(list: readonly Uint8Array[], totalLength?: number): Buffer
+	static concat(list: Buffer[], totalLength?: number): Buffer {
+		if (list.length === 0) return Buffer.alloc(0);
+
+		totalLength ??= list.reduce((acc, buf) => acc + buf.length, 0);
+
+		const buffer = Buffer.allocUnsafe(totalLength);
+		let offset = 0;
+		for (const buf of list) {
+			buffer.set(buf, offset);
+			offset += buf.length;
+		}
+		return buffer;
+	}
+
+	static isBuffer(obj: any): obj is Buffer {
+		return obj instanceof Buffer;
+	}
+
+	// 	byteLength(string: string | Buffer | NodeJS.ArrayBufferView | ArrayBufferLike, encoding?: BufferEncoding): number {}
+	static byteLength(string: string | ArrayBufferLike | NodeJS.ArrayBufferView, encoding: BufferEncoding = 'utf8'): number {
+		if (typeof string === 'string') {
+			return encode(string, encoding).length;
+		} else if (string instanceof ArrayBuffer || string instanceof SharedArrayBuffer || string instanceof Uint8Array) {
+			return string.byteLength;
+		} else {
+			throw new TypeError('The "string" argument must be one of type string, Buffer, or ArrayBuffer.');
+		}
+	}
+
+	static isEncoding(encoding: string): encoding is BufferEncoding {
+		return ['utf8', 'utf-8', 'ascii', 'latin1', 'binary', 'base64', 'base64url', 'hex', 'ucs2', 'ucs-2', 'utf16le', 'utf-16le'].includes(encoding.toLowerCase());
+	}
+
+	static compare(buf1: Uint8Array, buf2: Uint8Array): -1 | 0 | 1 {
+		if (!(buf1 instanceof Uint8Array) || !(buf2 instanceof Uint8Array)) {
+			throw new TypeError('Arguments must be Buffers');
+		}
+		if (buf1 === buf2) return 0;
+
+		for (let i = 0; i < Math.min(buf1.length, buf2.length); i++) {
+			if (buf1[i] !== buf2[i]) {
+				return buf1[i] < buf2[i] ? -1 : 1;
+			}
+		}
+		if (buf1.length < buf2.length) return -1;
+		if (buf1.length > buf2.length) return 1;
+		return 0;
+	}
+
+	static of(...items: number[]): Buffer {}
+
+	static copyBytesFrom(view: NodeJS.TypedArray, offset?: number, length?: number): Buffer {}
+
+	static allocUnsafeSlow(size: number): Buffer {}
+
+	static poolSize: number;
 }
 
+Buffer satisfies typeof NodeBuffer;
+
 function decode(data: Uint8Array, encoding: BufferEncoding) {
-	if (encoding == 'utf16le') encoding = 'utf-16le';
-	const decoder = new TextDecoder(encoding);
-	return decoder.decode(data);
+	switch (encoding) {
+		case 'base64':
+			return btoa(String.fromCharCode(...data));
+		case 'base64url':
+			return btoa(String.fromCharCode(...data))
+				.replace(/\+/g, '-')
+				.replace(/\//g, '_')
+				.replace(/=+$/, '');
+		case 'binary':
+			return String.fromCharCode(...data);
+		case 'hex':
+			return Array.from(data)
+				.map(byte => byte.toString(16).padStart(2, '0'))
+				.join('');
+		case 'utf16le':
+		case 'ucs2':
+		case 'ucs-2':
+			encoding = 'utf-16le';
+		// Fall through to use TextDecoder
+		default:
+			return new TextDecoder(encoding).decode(data);
+	}
+}
+
+function encode(input: string, encoding: BufferEncoding): Uint8Array {
+	switch (encoding) {
+		case 'utf-16le':
+		case 'utf16le':
+		case 'ucs2':
+		case 'ucs-2': {
+			const buffer = new Uint8Array(input.length * 2);
+			for (let i = 0; i < input.length; i++) {
+				const code = input.charCodeAt(i);
+				buffer[i * 2] = code & 0xff;
+				buffer[i * 2 + 1] = code >> 8;
+			}
+			return buffer;
+		}
+		case 'base64': {
+			const binaryString = atob(input);
+			const buffer = new Uint8Array(binaryString.length);
+			for (let i = 0; i < binaryString.length; i++) {
+				buffer[i] = binaryString.charCodeAt(i);
+			}
+			return buffer;
+		}
+		case 'base64url': {
+			input = input.replace(/-/g, '+').replace(/_/g, '/');
+			while (input.length % 4 !== 0) {
+				input += '=';
+			}
+			const binaryString = atob(input);
+			const buffer = new Uint8Array(binaryString.length);
+			for (let i = 0; i < binaryString.length; i++) {
+				buffer[i] = binaryString.charCodeAt(i);
+			}
+			return buffer;
+		}
+		case 'binary': {
+			const buffer = new Uint8Array(input.length);
+			for (let i = 0; i < input.length; i++) {
+				buffer[i] = input.charCodeAt(i);
+			}
+			return buffer;
+		}
+		case 'hex': {
+			const buffer = new Uint8Array(input.length / 2);
+			for (let i = 0; i < buffer.length; i++) {
+				buffer[i] = parseInt(input.substr(i * 2, 2), 16);
+			}
+			return buffer;
+		}
+		case 'ascii':
+		case 'utf8':
+		case 'utf-8':
+		case 'latin1':
+			return new TextEncoder().encode(input);
+	}
 }