simple-squiggle

LinkResolver.js (3215B)

---

 /*
 	MIT License http://www.opensource.org/licenses/mit-license.php
 	Author Tobias Koppers @sokra
 */
 "use strict";
 
 const fs = require("fs");
 const path = require("path");
 
 // macOS, Linux, and Windows all rely on these errors
 const EXPECTED_ERRORS = new Set(["EINVAL", "ENOENT"]);
 
 // On Windows there is also this error in some cases
 if (process.platform === "win32") EXPECTED_ERRORS.add("UNKNOWN");
 
 class LinkResolver {
 	constructor() {
 		this.cache = new Map();
 	}
 
 	/**
 	 * @param {string} file path to file or directory
 	 * @returns {string[]} array of file and all symlinks contributed in the resolving process (first item is the resolved file)
 	 */
 	resolve(file) {
 		const cacheEntry = this.cache.get(file);
 		if (cacheEntry !== undefined) {
 			return cacheEntry;
 		}
 		const parent = path.dirname(file);
 		if (parent === file) {
 			// At root of filesystem there can't be a link
 			const result = Object.freeze([file]);
 			this.cache.set(file, result);
 			return result;
 		}
 		// resolve the parent directory to find links there and get the real path
 		const parentResolved = this.resolve(parent);
 		let realFile = file;
 
 		// is the parent directory really somewhere else?
 		if (parentResolved[0] !== parent) {
 			// get the real location of file
 			const basename = path.basename(file);
 			realFile = path.resolve(parentResolved[0], basename);
 		}
 		// try to read the link content
 		try {
 			const linkContent = fs.readlinkSync(realFile);
 
 			// resolve the link content relative to the parent directory
 			const resolvedLink = path.resolve(parentResolved[0], linkContent);
 
 			// recursive resolve the link content for more links in the structure
 			const linkResolved = this.resolve(resolvedLink);
 
 			// merge parent and link resolve results
 			let result;
 			if (linkResolved.length > 1 && parentResolved.length > 1) {
 				// when both contain links we need to duplicate them with a Set
 				const resultSet = new Set(linkResolved);
 				// add the link
 				resultSet.add(realFile);
 				// add all symlinks of the parent
 				for (let i = 1; i < parentResolved.length; i++) {
 					resultSet.add(parentResolved[i]);
 				}
 				result = Object.freeze(Array.from(resultSet));
 			} else if (parentResolved.length > 1) {
 				// we have links in the parent but not for the link content location
 				result = parentResolved.slice();
 				result[0] = linkResolved[0];
 				// add the link
 				result.push(realFile);
 				Object.freeze(result);
 			} else if (linkResolved.length > 1) {
 				// we can return the link content location result
 				result = linkResolved.slice();
 				// add the link
 				result.push(realFile);
 				Object.freeze(result);
 			} else {
 				// neither link content location nor parent have links
 				// this link is the only link here
 				result = Object.freeze([
 					// the resolve real location
 					linkResolved[0],
 					// add the link
 					realFile
 				]);
 			}
 			this.cache.set(file, result);
 			return result;
 		} catch (e) {
 			if (!EXPECTED_ERRORS.has(e.code)) {
 				throw e;
 			}
 			// no link
 			const result = parentResolved.slice();
 			result[0] = realFile;
 			Object.freeze(result);
 			this.cache.set(file, result);
 			return result;
 		}
 	}
 }
 module.exports = LinkResolver;