source: frontend/node_modules/enhanced-resolve/lib/util/fs.js

/*
        MIT License http://www.opensource.org/licenses/mit-license.php
        Author Natsu @xiaoxiaojx
*/

"use strict";

const stripJsonComments = require("./strip-json-comments");

/** @typedef {import("../Resolver").FileSystem} FileSystem */
/** @typedef {import("../Resolver").JsonObject} JsonObject */

/**
 * @typedef {object} ReadJsonOptions
 * @property {boolean=} stripComments Whether to strip JSONC comments
 */

/** @type {WeakMap<Buffer, JsonObject>} */
const _stripCommentsCache = new WeakMap();

/**
 * Read and parse JSON file (supports JSONC with comments).
 * Callback-based so a synchronous `fileSystem` stays synchronous all the
 * way through — Promise wrapping would defer resolution by a Promise tick
 * and break `resolveSync` when `tsconfig` is used together with
 * `useSyncFileSystemCalls: true`.
 * @param {FileSystem} fileSystem the file system
 * @param {string} jsonFilePath absolute path to JSON file
 * @param {ReadJsonOptions} options Options
 * @param {(err: NodeJS.ErrnoException | Error | null, content?: JsonObject) => void} callback callback
 * @returns {void}
 */
function readJson(fileSystem, jsonFilePath, options, callback) {
        const { stripComments = false } = options;
        const { readJson: fsReadJson } = fileSystem;
        if (fsReadJson && !stripComments) {
                fsReadJson(jsonFilePath, (err, content) => {
                        if (err) return callback(err);
                        callback(null, /** @type {JsonObject} */ (content));
                });
                return;
        }

        fileSystem.readFile(jsonFilePath, (err, data) => {
                if (err) return callback(err);
                const buf = /** @type {Buffer} */ (data);

                if (stripComments) {
                        const cached = _stripCommentsCache.get(buf);
                        if (cached !== undefined) return callback(null, cached);
                }

                let result;
                try {
                        const jsonText = buf.toString();
                        const jsonWithoutComments = stripComments
                                ? stripJsonComments(jsonText, {
                                                trailingCommas: true,
                                                whitespace: true,
                                        })
                                : jsonText;
                        result = JSON.parse(jsonWithoutComments);
                } catch (parseErr) {
                        return callback(/** @type {Error} */ (parseErr));
                }

                if (stripComments) {
                        _stripCommentsCache.set(buf, result);
                }

                callback(null, result);
        });
}

module.exports.readJson = readJson;