jeudi 6 juin 2019

Partial classes, design patterns

Could you say splitting a class into partial classes is a way to encapsulate your code?

Also, why is splitting a code into partial classes not a part of a design pattern? I mean you kind of design the code by splitting it up for a better overview, right?

General.cs:

/*  SINGLETON DESIGN PATTERN (slides and https://sourcemaking.com/design_patterns/singleton)

     * INTENT
       - Ensure a class has only one instance, and provide a global point of access to it.
       - Encapsulated "just-in-time initialization" or "initialization on first use".

      * ABOUT
       - Make the class of the single instance object responsible for creation, initialization,
       access, and enforcement.

 */
namespace SpaceTaxi_3.States.GameRunning.Parser {
    public partial class LevelParser {

        private static LevelParser instance;

        public static LevelParser GetInstance() {
            return LevelParser.instance ?? (LevelParser.instance = new LevelParser());
        }

        public Dictionary<char, string> Obstacles;
        public Dictionary<char, string> Platforms;
        public Dictionary<char, string> Exits;
        public Dictionary<string, Tuple<int, char, string, int, int, Entity>> Costumer;
        public List<Entity> ObstacleEntities { get; set; }
        public List<Platform> PlatformEntities { get; set; }
        public List<Entity> ExitEntities { get; set; }

        public string[] LevelFile;

        // Wrapper
        public void Load(string fileName) {

            // Catches incorrect files here
            if (ValidMapCheck(fileName)) {
                PlatformEntities = new List<Platform>();
                ExitEntities = new List<Entity>();
                ObstacleEntities = new List<Entity>();

                Platforms = new Dictionary<char, string>();
                Exits = new Dictionary<char, string>();
                Obstacles = new Dictionary<char, string>();
                Costumer = new Dictionary<string, Tuple<int, char, string, int, int, Entity>>();

                LevelFile = ReadFile("Levels", fileName);

                Platforms = GetPlatforms(LevelFile);
                Exits = GetExits(LevelFile);
                Obstacles = GetObstacles(LevelFile);
                Costumer = GetCustomerInfo(LevelFile);

                AddEntities(GetAllTiles(LevelFile));
            }
        }

        /// <summary>
        ///  Checks whether a file exists or not
        /// </summary>
        private void ValidatePath(string file) {
            if (!File.Exists(file)) {
                throw new FileNotFoundException($"Error: " +
                                                $"The path to \"{file}\" does not exist.");
            }
        }

        /// <summary>
        ///  Finds full path to directory (e.g. directoryName: "Levels" or "Assets")
        ///  Starts from /bin/Debug folder, then goes to parent /bin, and so on.
        ///  Casts an exception if we iterated down to the root of the tree.
        /// </summary>
        private string GetPath(string directoryName) {
            DirectoryInfo dir = new DirectoryInfo(Path.GetDirectoryName(System.Reflection.Assembly.
                GetExecutingAssembly().Location));

            while (dir.Name != directoryName) {
                if (dir.FullName == dir.Root.Name) {
                    throw new FileNotFoundException(
                        $"Error: Directory \"{directoryName}\" does not exist.");
                } else {
                    foreach (var i in dir.GetDirectories()) {
                        if (i.Name == directoryName) {
                            return i.FullName;
                        }
                    }

                    dir = dir.Parent;
                }
            }
            return dir.FullName;
        }

        /// <summary>
        /// Making sure our mapfiles are not tampered with by calculating the checksum
        /// Source: https://stackoverflow.com/questions/10520048/calculate-md5-checksum-for-a-file
        /// Source: https://en.wikipedia.org/wiki/MD5
        /// </summary>
        /// <param name="filename"></param>
        public string CheckMD5(string filename)
        {
            // "using": automatically disposes the object after use,
            //  even if exception is casted
            using (var md5 = MD5.Create())
            {
                using (var stream = File.OpenRead(filename))
                {
                    var hash = md5.ComputeHash(stream);
                    return BitConverter.ToString(hash).Replace("-", "").ToLowerInvariant();
                }
            }
        }

        /// <summary>
        ///  Checks for invalid files and invalid filecontent
        /// </summary>
        public bool ValidMapCheck(string filename) {

            var hash = "";
            var hash32bit = "";
            Console.WriteLine("Hash: " + CheckMD5(Path.Combine(GetPath("Levels"), filename)));

            // Checks for invalid files
            if (filename != "the-beach.txt" && filename != "short-n-sweet.txt") {
                throw new ArgumentException($"Parser cannot load: {filename}");
            }

            // Checks for invalid file content
            if (filename == "the-beach.txt") {
                hash = "81b89b1908e3b3b7fcd7526810c32f14";
                hash32bit = "34d0e9c5ea54bfc60a0365f28b7d3a19";
            }
            if (filename == "short-n-sweet.txt") {
                hash = "e97f28bfff174f9643c088814377ada6";
                hash32bit = "5c4832a9a5510bdab5976ad0e6905e85";

            }

            var checksum = CheckMD5(Path.Combine(GetPath("Levels"), filename));
            if (checksum == hash || checksum == hash32bit) {
                return true;
            }
            throw new ArgumentException($"You've tampered with {filename}!");
            // Todo: Find out how to hide these hash strings and to avoid inline hardcode
        }

        /// <summary>
        ///  Collects a string[] containing all strings in the file
        /// </summary>
        private string[] ReadFile(string directoryName, string fileName) {
            var dir = GetPath(directoryName);
            string path = Path.Combine(dir, fileName);
            ValidatePath(path);
            return File.ReadAllLines(path);
        }

        /// <summary>
        ///  Extracts ASCII characters from the txt file and appends it
        ///  to an array. Later we will use this array to draw pictures.
        /// </summary>
        private List<char> GetAllTiles(string[] txtFile) {
            var charList = new List<char>();
            for (int i = 0; i < 23; i++) {
                foreach (var j in txtFile[i]) {
                    charList.Add(j);
                }
            }

            return charList;
        }

        /// <summary>
        ///    Adds all objects to the appropriate map being loaded
        ///    We iterate from top-left (0,1) of the screen to bottom-right (1,0)
        /// </summary>
        private void AddEntities(List<char> map) {
            float tmpX = Constants.X_MIN;
            float tmpY = Constants.Y_MAX;

            int index = 0;

            // Going from top (y 1.0) to bottom (y 0.0)
            while (tmpY > Constants.Y_MIN) {

                // Going from left (x 0.0) to right (x 1.0)
                while (tmpX < Constants.X_MAX) {

                    // There can be empty strings in our list of strings.
                    if (map[index].ToString() == " ") {
                        index += 1;

                    } else {
                        // Adds obstacles
                        if (Obstacles.ContainsKey(map[index])) {
                            var shape = new StationaryShape(new Vec2F(tmpX, tmpY),
                                new Vec2F(Constants.WIDTH, Constants.HEIGHT));
                            var file = Path.Combine(GetPath("Assets"),
                                "Images", Obstacles[map[index]]);
                            ValidatePath(file);
                            ObstacleEntities.Add(new Entity(shape, new Image(file)));
                        }

                        // Adds platforms
                        if (Platforms.ContainsKey(map[index])) {
                            var shape = new StationaryShape(new Vec2F(tmpX, tmpY),
                                new Vec2F(Constants.WIDTH, Constants.HEIGHT));
                            var file = Path.Combine(GetPath("Assets"), "Images",
                                Platforms[map[index]]);
                            ValidatePath(file);
                            PlatformEntities.Add(new Platform(shape, new Image(file), map[index]));
                        }

                        // Adds exits
                        if (Exits.ContainsKey(map[index])) {
                            var shape = new StationaryShape(new Vec2F(tmpX, tmpY),
                                new Vec2F(Constants.WIDTH, Constants.HEIGHT));
                            var file = Path.Combine(GetPath("Assets"), "Images",
                                Exits[map[index]]);
                            ValidatePath(file);
                            ExitEntities.Add(new Entity(shape, new Image(file)));
                        }

                        // Update index
                        index += 1;
                    }

                    tmpX += Constants.WIDTH;
                }

                tmpX = 0;
                tmpY -= Constants.HEIGHT;
            }
        }
    }
}

ParseCustomer.cs:

public partial class LevelParser {
    public Dictionary<string, Tuple<int, char, string, int, int, Entity>>
        GetCustomerInfo(string[] txtFile) {

        // Creates a dictionary containing all info about the customer
        var retDict = new Dictionary<string, Tuple<int, char, string, int, int, Entity>>();

        // Iterates over the entire txtFile and finds certain string
        IEnumerable<string> findName = txtFile.Where(l => l.StartsWith("Customer: "));
        foreach (var line in findName)
        {
            // Parses file
            var name = line.Split(' ')[1];
            var timeBeforeSpawn = Convert.ToInt32(line.Split(' ')[2]); // seconds
            var spawnOnPlatform = Convert.ToChar(line.Split(' ')[3]);
            var destinationPlat = line.Split(' ')[4]; // string
            var patienceTime = Convert.ToInt32(line.Split(' ')[5]); // seconds
            var rewardPoints = Convert.ToInt32(line.Split(' ')[6]);

            // Adds an entity
            var shape = new DynamicShape(new Vec2F(), new Vec2F());
            var image = new Image(Path.Combine("Assets", "Images", "CustomerStandLeft.png"));
            var entity = new Entity(shape, image);

            retDict.Add(name, new Tuple<int, char, string, int, int, Entity>(timeBeforeSpawn,
                spawnOnPlatform, destinationPlat, patienceTime, rewardPoints, entity));

        }

        // Now we have everything we need in one dictionary
        return retDict;
    }
}

There are 3 more files each containing the same partial class but has a method which does something different than the others.

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