webpack/lib/cache/MemoryCachePlugin.js

Packs ECMAScript/CommonJs/AMD modules for the browser. Allows you to split your codebase into multiple bundles, which can be loaded on demand. Supports 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 Cache = require("../Cache");

/** @typedef {import("webpack-sources").Source} Source */
/** @typedef {import("../Cache").Etag} Etag */
/** @typedef {import("../Compiler")} Compiler */
/** @typedef {import("../Module")} Module */

class MemoryCachePlugin {
	/**
	 * Apply the plugin
	 * @param {Compiler} compiler the compiler instance
	 * @returns {void}
	 */
	apply(compiler) {
		/** @type {Map<string, { etag: Etag | null, data: any } | null>} */
		const cache = new Map();
		compiler.cache.hooks.store.tap(
			{ name: "MemoryCachePlugin", stage: Cache.STAGE_MEMORY },
			(identifier, etag, data) => {
				cache.set(identifier, { etag, data });
			}
		);
		compiler.cache.hooks.get.tap(
			{ name: "MemoryCachePlugin", stage: Cache.STAGE_MEMORY },
			(identifier, etag, gotHandlers) => {
				const cacheEntry = cache.get(identifier);
				if (cacheEntry === null) {
					return null;
				} else if (cacheEntry !== undefined) {
					return cacheEntry.etag === etag ? cacheEntry.data : null;
				}
				gotHandlers.push((result, callback) => {
					if (result === undefined) {
						cache.set(identifier, null);
					} else {
						cache.set(identifier, { etag, data: result });
					}
					return callback();
				});
			}
		);
		compiler.cache.hooks.shutdown.tap(
			{ name: "MemoryCachePlugin", stage: Cache.STAGE_MEMORY },
			() => {
				cache.clear();
			}
		);
	}
}
module.exports = MemoryCachePlugin;