webpack/lib/RequestShortener.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 path = require("path");
const NORMALIZE_SLASH_DIRECTION_REGEXP = /\\/g;
const PATH_CHARS_REGEXP = /[-[\]{}()*+?.,\\^$|#\s]/g;
const SEPARATOR_REGEXP = /[/\\]$/;
const FRONT_OR_BACK_BANG_REGEXP = /^!|!$/g;
const INDEX_JS_REGEXP = /\/index.js(!|\?|\(query\))/g;
const MATCH_RESOURCE_REGEXP = /!=!/;

const normalizeBackSlashDirection = request => {
	return request.replace(NORMALIZE_SLASH_DIRECTION_REGEXP, "/");
};

const createRegExpForPath = path => {
	const regexpTypePartial = path.replace(PATH_CHARS_REGEXP, "\\$&");
	return new RegExp(`(^|!)${regexpTypePartial}`, "g");
};

class RequestShortener {
	constructor(directory) {
		directory = normalizeBackSlashDirection(directory);
		if (SEPARATOR_REGEXP.test(directory)) {
			directory = directory.substr(0, directory.length - 1);
		}

		if (directory) {
			this.currentDirectoryRegExp = createRegExpForPath(directory);
		}

		const dirname = path.dirname(directory);
		const endsWithSeparator = SEPARATOR_REGEXP.test(dirname);
		const parentDirectory = endsWithSeparator
			? dirname.substr(0, dirname.length - 1)
			: dirname;
		if (parentDirectory && parentDirectory !== directory) {
			this.parentDirectoryRegExp = createRegExpForPath(`${parentDirectory}/`);
		}

		if (__dirname.length >= 2) {
			const buildins = normalizeBackSlashDirection(path.join(__dirname, ".."));
			const buildinsAsModule =
				this.currentDirectoryRegExp &&
				this.currentDirectoryRegExp.test(buildins);
			this.buildinsAsModule = buildinsAsModule;
			this.buildinsRegExp = createRegExpForPath(buildins);
		}

		this.cache = new Map();
	}

	shorten(request) {
		if (!request) return request;
		const cacheEntry = this.cache.get(request);
		if (cacheEntry !== undefined) {
			return cacheEntry;
		}
		let result = normalizeBackSlashDirection(request);
		if (this.buildinsAsModule && this.buildinsRegExp) {
			result = result.replace(this.buildinsRegExp, "!(webpack)");
		}
		if (this.currentDirectoryRegExp) {
			result = result.replace(this.currentDirectoryRegExp, "!.");
		}
		if (this.parentDirectoryRegExp) {
			result = result.replace(this.parentDirectoryRegExp, "!../");
		}
		if (!this.buildinsAsModule && this.buildinsRegExp) {
			result = result.replace(this.buildinsRegExp, "!(webpack)");
		}
		result = result.replace(INDEX_JS_REGEXP, "$1");
		result = result.replace(FRONT_OR_BACK_BANG_REGEXP, "");
		result = result.replace(MATCH_RESOURCE_REGEXP, " = ");
		this.cache.set(request, result);
		return result;
	}
}

module.exports = RequestShortener;