source: trip-planner-front/node_modules/memory-fs/lib/normalize.js@ eed0bf8

module.exports = function normalize(path) {
        var parts = path.split(/(\\+|\/+)/);
        if(parts.length === 1)
                return path;
        var result = [];
        var absolutePathStart = 0;
        for(var i = 0, sep = false; i < parts.length; i++, sep = !sep) {
                var part = parts[i];
                if(i === 0 && /^([A-Z]:)?$/i.test(part)) {
                        result.push(part);
                        absolutePathStart = 2;
                } else if(sep) {
                        result.push(part[0]);
                } else if(part === "..") {
                        switch(result.length) {
                                case 0:
                                        // i. e. ".." => ".."
                                        // i. e. "../a/b/c" => "../a/b/c"
                                        result.push(part);
                                        break;
                                case 2:
                                        // i. e. "a/.." => ""
                                        // i. e. "/.." => "/"
                                        // i. e. "C:\.." => "C:\"
                                        // i. e. "a/../b/c" => "b/c"
                                        // i. e. "/../b/c" => "/b/c"
                                        // i. e. "C:\..\a\b\c" => "C:\a\b\c"
                                        i++;
                                        sep = !sep;
                                        result.length = absolutePathStart;
                                        break;
                                case 4:
                                        // i. e. "a/b/.." => "a"
                                        // i. e. "/a/.." => "/"
                                        // i. e. "C:\a\.." => "C:\"
                                        // i. e. "/a/../b/c" => "/b/c"
                                        if(absolutePathStart === 0) {
                                                result.length -= 3;
                                        } else {
                                                i++;
                                                sep = !sep;
                                                result.length = 2;
                                        }
                                        break;
                                default:
                                        // i. e. "/a/b/.." => "/a"
                                        // i. e. "/a/b/../c" => "/a/c"
                                        result.length -= 3;
                                        break;
                        }
                } else if(part === ".") {
                        switch(result.length) {
                                case 0:
                                        // i. e. "." => "."
                                        // i. e. "./a/b/c" => "./a/b/c"
                                        result.push(part);
                                        break;
                                case 2:
                                        // i. e. "a/." => "a"
                                        // i. e. "/." => "/"
                                        // i. e. "C:\." => "C:\"
                                        // i. e. "C:\.\a\b\c" => "C:\a\b\c"
                                        if(absolutePathStart === 0) {
                                                result.length--;
                                        } else {
                                                i++;
                                                sep = !sep;
                                        }
                                        break;
                                default:
                                        // i. e. "a/b/." => "a/b"
                                        // i. e. "/a/." => "/"
                                        // i. e. "C:\a\." => "C:\"
                                        // i. e. "a/./b/c" => "a/b/c"
                                        // i. e. "/a/./b/c" => "/a/b/c"
                                        result.length--;
                                        break;
                        }
                } else if(part) {
                        result.push(part);
                }
        }
        if(result.length === 1 && /^[A-Za-z]:$/.test(result))
                return result[0] + "\\";
        return result.join("");
};