webpack/lib/util/createHash.js

Packs CommonJs/AMD modules for the browser. Allows to split your codebase into multiple bundles, which can be loaded on demand. Support loaders to preprocess files, i.e. json, jsx, es7, css, less, ... and your custom stuff.

/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/
"use strict";

const AbstractMethodError = require("../AbstractMethodError");

const BULK_SIZE = 1000;

class Hash {
	/**
	 * Update hash {@link https://nodejs.org/api/crypto.html#crypto_hash_update_data_inputencoding}
	 * @param {string|Buffer} data data
	 * @param {string=} inputEncoding data encoding
	 * @returns {this} updated hash
	 */
	update(data, inputEncoding) {
		throw new AbstractMethodError();
	}

	/**
	 * Calculates the digest {@link https://nodejs.org/api/crypto.html#crypto_hash_digest_encoding}
	 * @param {string=} encoding encoding of the return value
	 * @returns {string|Buffer} digest
	 */
	digest(encoding) {
		throw new AbstractMethodError();
	}
}

exports.Hash = Hash;
/** @typedef {typeof Hash} HashConstructor */

class BulkUpdateDecorator extends Hash {
	/**
	 * @param {Hash} hash hash
	 */
	constructor(hash) {
		super();
		this.hash = hash;
		this.buffer = "";
	}

	/**
	 * Update hash {@link https://nodejs.org/api/crypto.html#crypto_hash_update_data_inputencoding}
	 * @param {string|Buffer} data data
	 * @param {string=} inputEncoding data encoding
	 * @returns {this} updated hash
	 */
	update(data, inputEncoding) {
		if (
			inputEncoding !== undefined ||
			typeof data !== "string" ||
			data.length > BULK_SIZE
		) {
			if (this.buffer.length > 0) {
				this.hash.update(this.buffer);
				this.buffer = "";
			}
			this.hash.update(data, inputEncoding);
		} else {
			this.buffer += data;
			if (this.buffer.length > BULK_SIZE) {
				this.hash.update(this.buffer);
				this.buffer = "";
			}
		}
		return this;
	}

	/**
	 * Calculates the digest {@link https://nodejs.org/api/crypto.html#crypto_hash_digest_encoding}
	 * @param {string=} encoding encoding of the return value
	 * @returns {string|Buffer} digest
	 */
	digest(encoding) {
		if (this.buffer.length > 0) {
			this.hash.update(this.buffer);
		}
		var digestResult = this.hash.digest(encoding);
		return typeof digestResult === "string"
			? digestResult
			: digestResult.toString();
	}
}

/**
 * istanbul ignore next
 */
class DebugHash extends Hash {
	constructor() {
		super();
		this.string = "";
	}

	/**
	 * Update hash {@link https://nodejs.org/api/crypto.html#crypto_hash_update_data_inputencoding}
	 * @param {string|Buffer} data data
	 * @param {string=} inputEncoding data encoding
	 * @returns {this} updated hash
	 */
	update(data, inputEncoding) {
		if (typeof data !== "string") data = data.toString("utf-8");
		this.string += data;
		return this;
	}

	/**
	 * Calculates the digest {@link https://nodejs.org/api/crypto.html#crypto_hash_digest_encoding}
	 * @param {string=} encoding encoding of the return value
	 * @returns {string|Buffer} digest
	 */
	digest(encoding) {
		return this.string.replace(/[^a-z0-9]+/gi, m =>
			Buffer.from(m).toString("hex")
		);
	}
}

/**
 * Creates a hash by name or function
 * @param {string | HashConstructor} algorithm the algorithm name or a constructor creating a hash
 * @returns {Hash} the hash
 */
module.exports = algorithm => {
	if (typeof algorithm === "function") {
		return new BulkUpdateDecorator(new algorithm());
	}
	switch (algorithm) {
		// TODO add non-cryptographic algorithm here
		case "debug":
			return new DebugHash();
		default:
			return new BulkUpdateDecorator(require("crypto").createHash(algorithm));
	}
};