From efbc2ffe6a1ee5ec38a4396305561d6515d0943e Mon Sep 17 00:00:00 2001 From: littleblack111 Date: Fri, 30 Aug 2024 17:21:18 +0800 Subject: node fixes, updates --- node_modules/webpack/lib/util/StringXor.js | 101 +++++++++++++++++++++++++++++ 1 file changed, 101 insertions(+) create mode 100644 node_modules/webpack/lib/util/StringXor.js (limited to 'node_modules/webpack/lib/util/StringXor.js') diff --git a/node_modules/webpack/lib/util/StringXor.js b/node_modules/webpack/lib/util/StringXor.js new file mode 100644 index 00000000..ea5c8f83 --- /dev/null +++ b/node_modules/webpack/lib/util/StringXor.js @@ -0,0 +1,101 @@ +/* + MIT License http://www.opensource.org/licenses/mit-license.php + Author Tobias Koppers @sokra +*/ + +"use strict"; + +/** @typedef {import("../util/Hash")} Hash */ + +/** + * StringXor class provides methods for performing + * [XOR operations](https://en.wikipedia.org/wiki/Exclusive_or) on strings. In this context + * we operating on the character codes of two strings, which are represented as + * [Buffer](https://nodejs.org/api/buffer.html) objects. + * + * We use [StringXor in webpack](https://github.com/webpack/webpack/commit/41a8e2ea483a544c4ccd3e6217bdfb80daffca39) + * to create a hash of the current state of the compilation. By XOR'ing the Module hashes, it + * doesn't matter if the Module hashes are sorted or not. This is useful because it allows us to avoid sorting the + * Module hashes. + * @example + * ```js + * const xor = new StringXor(); + * xor.add('hello'); + * xor.add('world'); + * console.log(xor.toString()); + * ``` + * @example + * ```js + * const xor = new StringXor(); + * xor.add('foo'); + * xor.add('bar'); + * const hash = createHash('sha256'); + * hash.update(xor.toString()); + * console.log(hash.digest('hex')); + * ``` + */ +class StringXor { + constructor() { + /** @type {Buffer|undefined} */ + this._value = undefined; + } + + /** + * Adds a string to the current StringXor object. + * @param {string} str string + * @returns {void} + */ + add(str) { + const len = str.length; + const value = this._value; + if (value === undefined) { + /** + * We are choosing to use Buffer.allocUnsafe() because it is often faster than Buffer.alloc() because + * it allocates a new buffer of the specified size without initializing the memory. + */ + const newValue = (this._value = Buffer.allocUnsafe(len)); + for (let i = 0; i < len; i++) { + newValue[i] = str.charCodeAt(i); + } + return; + } + const valueLen = value.length; + if (valueLen < len) { + const newValue = (this._value = Buffer.allocUnsafe(len)); + let i; + for (i = 0; i < valueLen; i++) { + newValue[i] = value[i] ^ str.charCodeAt(i); + } + for (; i < len; i++) { + newValue[i] = str.charCodeAt(i); + } + } else { + for (let i = 0; i < len; i++) { + value[i] = value[i] ^ str.charCodeAt(i); + } + } + } + + /** + * Returns a string that represents the current state of the StringXor object. We chose to use "latin1" encoding + * here because "latin1" encoding is a single-byte encoding that can represent all characters in the + * [ISO-8859-1 character set](https://en.wikipedia.org/wiki/ISO/IEC_8859-1). This is useful when working + * with binary data that needs to be represented as a string. + * @returns {string} Returns a string that represents the current state of the StringXor object. + */ + toString() { + const value = this._value; + return value === undefined ? "" : value.toString("latin1"); + } + + /** + * Updates the hash with the current state of the StringXor object. + * @param {Hash} hash Hash instance + */ + updateHash(hash) { + const value = this._value; + if (value !== undefined) hash.update(value); + } +} + +module.exports = StringXor; -- cgit v1.2.3