node_modules/enhanced-resolve/lib/DescriptionFileUtils.js

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

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

function loadDescriptionFile(resolver, directory, filenames, resolveContext, callback) {
	(function findDescriptionFile() {
		forEachBail(filenames, (filename, callback) => {
			const descriptionFilePath = resolver.join(directory, filename);
			if(resolver.fileSystem.readJson) {
				resolver.fileSystem.readJson(descriptionFilePath, (err, content) => {
					if(err) {
						if(typeof err.code !== "undefined") return callback();
						return onJson(err);
					}
					onJson(null, content);
				});
			} else {
				resolver.fileSystem.readFile(descriptionFilePath, (err, content) => {
					if(err) return callback();
					let json;
					try {
						json = JSON.parse(content);
					} catch(e) {
						onJson(e);
					}
					onJson(null, json);
				});
			}

			function onJson(err, content) {
				if(err) {
					if(resolveContext.log)
						resolveContext.log(descriptionFilePath + " (directory description file): " + err);
					else
						err.message = descriptionFilePath + " (directory description file): " + err;
					return callback(err);
				}
				callback(null, {
					content: content,
					directory: directory,
					path: descriptionFilePath
				});
			}
		}, (err, result) => {
			if(err) return callback(err);
			if(result) {
				return callback(null, result);
			} else {
				directory = cdUp(directory);
				if(!directory) {
					return callback();
				} else {
					return findDescriptionFile();
				}
			}
		});
	}());
}

function getField(content, field) {
	if(!content) return undefined;
	if(Array.isArray(field)) {
		let current = content;
		for(let j = 0; j < field.length; j++) {
			if(current === null || typeof current !== "object") {
				current = null;
				break;
			}
			current = current[field[j]];
		}
		if(typeof current === "object") {
			return current;
		}
	} else {
		if(typeof content[field] === "object") {
			return content[field];
		}
	}
}

function cdUp(directory) {
	if(directory === "/") return null;
	const i = directory.lastIndexOf("/"),
		j = directory.lastIndexOf("\\");
	const p = i < 0 ? j : j < 0 ? i : i < j ? j : i;
	if(p < 0) return null;
	return directory.substr(0, p || 1);
}

exports.loadDescriptionFile = loadDescriptionFile;
exports.getField = getField;
exports.cdUp = cdUp;