webpack/lib/util/identifier.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.

"use strict";
const path = require("path");

/**
 * @typedef {Object} MakeRelativePathsCache
 * @property {Map<string, Map<string, string>>=} relativePaths
 */

/**
 *
 * @param {string} maybeAbsolutePath path to check
 * @returns {boolean} returns true if path is "Absolute Path"-like
 */
const looksLikeAbsolutePath = maybeAbsolutePath => {
	if (/^\/.*\/$/.test(maybeAbsolutePath)) {
		// this 'path' is actually a regexp generated by dynamic requires.
		// Don't treat it as an absolute path.
		return false;
	}
	return /^(?:[a-z]:\\|\/)/i.test(maybeAbsolutePath);
};

/**
 *
 * @param {string} p path to normalize
 * @returns {string} normalized version of path
 */
const normalizePathSeparator = p => p.replace(/\\/g, "/");

/**
 *
 * @param {string} context context for relative path
 * @param {string} identifier identifier for path
 * @returns {string} a converted relative path
 */
const _makePathsRelative = (context, identifier) => {
	return identifier
		.split(/([|! ])/)
		.map(str =>
			looksLikeAbsolutePath(str)
				? normalizePathSeparator(path.relative(context, str))
				: str
		)
		.join("");
};

/**
 *
 * @param {string} context context used to create relative path
 * @param {string} identifier identifier used to create relative path
 * @param {MakeRelativePathsCache=} cache the cache object being set
 * @returns {string} the returned relative path
 */
exports.makePathsRelative = (context, identifier, cache) => {
	if (!cache) return _makePathsRelative(context, identifier);

	const relativePaths =
		cache.relativePaths || (cache.relativePaths = new Map());

	let cachedResult;
	let contextCache = relativePaths.get(context);
	if (contextCache === undefined) {
		relativePaths.set(context, (contextCache = new Map()));
	} else {
		cachedResult = contextCache.get(identifier);
	}

	if (cachedResult !== undefined) {
		return cachedResult;
	} else {
		const relativePath = _makePathsRelative(context, identifier);
		contextCache.set(identifier, relativePath);
		return relativePath;
	}
};

/**
 * @param {string} context absolute context path
 * @param {string} request any request string may containing absolute paths, query string, etc.
 * @returns {string} a new request string avoiding absolute paths when possible
 */
exports.contextify = (context, request) => {
	return request
		.split("!")
		.map(r => {
			const splitPath = r.split("?", 2);
			if (/^[a-zA-Z]:\\/.test(splitPath[0])) {
				splitPath[0] = path.win32.relative(context, splitPath[0]);
				if (!/^[a-zA-Z]:\\/.test(splitPath[0])) {
					splitPath[0] = splitPath[0].replace(/\\/g, "/");
				}
			}
			if (/^\//.test(splitPath[0])) {
				splitPath[0] = path.posix.relative(context, splitPath[0]);
			}
			if (!/^(\.\.\/|\/|[a-zA-Z]:\\)/.test(splitPath[0])) {
				splitPath[0] = "./" + splitPath[0];
			}
			return splitPath.join("?");
		})
		.join("!");
};