source: frontend/node_modules/webpack/lib/dependencies/LocalModulesHelpers.js

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

"use strict";

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

/** @typedef {import("../javascript/JavascriptParser").JavascriptParserState} JavascriptParserState */

/**
 * Returns resolved module.
 * @param {string} parent parent module
 * @param {string} mod module to resolve
 * @returns {string} resolved module
 */
const lookup = (parent, mod) => {
        if (mod.charAt(0) !== ".") return mod;

        const path = parent.split("/");
        const segments = mod.split("/");
        path.pop();

        for (let i = 0; i < segments.length; i++) {
                const seg = segments[i];
                if (seg === "..") {
                        path.pop();
                } else if (seg !== ".") {
                        path.push(seg);
                }
        }

        return path.join("/");
};

/**
 * Returns local module.
 * @param {JavascriptParserState} state parser state
 * @param {string} name name
 * @returns {LocalModule} local module
 */
module.exports.addLocalModule = (state, name) => {
        if (!state.localModules) {
                state.localModules = [];
        }
        const m = new LocalModule(name, state.localModules.length);
        state.localModules.push(m);
        return m;
};

/**
 * Returns local module or null.
 * @param {JavascriptParserState} state parser state
 * @param {string} name name
 * @param {string=} namedModule named module
 * @returns {LocalModule | null} local module or null
 */
module.exports.getLocalModule = (state, name, namedModule) => {
        if (!state.localModules) return null;
        if (namedModule) {
                // resolve dependency name relative to the defining named module
                name = lookup(namedModule, name);
        }
        for (let i = 0; i < state.localModules.length; i++) {
                if (state.localModules[i].name === name) {
                        return state.localModules[i];
                }
        }
        return null;
};