Add some class for parsing command arguments

src/MineCase.Server.Grains/Game/Entities/PlayerGrain.cs

@@ -133,7 +133,12 @@ public Task SetLook(float yaw, float pitch, bool onGround)
             return Task.CompletedTask;
         }
 
-        public bool HasPermission(Permission permission)
+        public Task<bool> HasPermission(Permission permission)
+        {
+            throw new NotImplementedException();
+        }
+
+        public Task SendMessage(string msg)
         {
             throw new NotImplementedException();
         }

src/MineCase.Server.Grains/Game/GameSession.cs

@@ -21,6 +21,8 @@ internal class GameSession : Grain, IGameSession
         private IDisposable _gameTick;
         private DateTime _lastGameTickTime;
 
+        private readonly Commands.CommandMap _commandMap = new Commands.CommandMap();
+
         public override async Task OnActivateAsync()
         {
             _world = await GrainFactory.GetGrain<IWorldAccessor>(0).GetWorld(this.GetPrimaryKeyString());
@@ -61,10 +63,23 @@ public async Task SendChatMessage(IUser sender, string message)
         {
             var senderName = await sender.GetName();
 
-            // TODO command parser
+            if (!string.IsNullOrWhiteSpace(message))
+            {
+                var command = message.Trim();
+                if (command[0] == '/')
+                {
+                    if (!_commandMap.Dispatch(await sender.GetPlayer(), message))
+                    {
+                        // TODO: 处理命令未成功执行的情形
+                    }
+
+                    return;
+                }
+            }
+
             // construct name
-            Chat jsonData = await CreateStandardChatMessage(senderName, message);
-            byte position = 0; // It represents user message in chat box
+            var jsonData = await CreateStandardChatMessage(senderName, message);
+            const byte position = 0; // It represents user message in chat box
             foreach (var item in _users.Keys)
             {
                 await item.SendChatMessage(jsonData, position);

src/MineCase.Server.Interfaces/Game/Commands/CommandMap.cs

@@ -0,0 +1,33 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace MineCase.Server.Game.Commands
+{
+    public class CommandMap
+    {
+        private readonly Dictionary<string, ICommand> _commandMap = new Dictionary<string, ICommand>();
+
+        public void RegisterCommand(ICommand command)
+        {
+            _commandMap.Add(command.Name, command);
+        }
+
+        public bool Dispatch(ICommandSender sender, string commandContent)
+        {
+            var (commandName, args) = CommandParser.ParseCommand(commandContent);
+
+            try
+            {
+                return _commandMap.TryGetValue(commandName, out var command) &&
+                       (command.NeededPermission == null || sender.HasPermission(command.NeededPermission).Result) &&
+                       command.Execute(sender, args);
+            }
+            catch (CommandException e)
+            {
+                sender.SendMessage($"在执行指令 {commandName} 之时发生指令相关的异常 {e}");
+                return false;
+            }
+        }
+    }
+}

src/MineCase.Server.Interfaces/Game/Commands/CommandParser.cs

@@ -0,0 +1,87 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Diagnostics.Contracts;
+using System.Linq;
+using System.Text;
+
+namespace MineCase.Server.Game.Commands
+{
+    /// <summary>
+    /// 未解析参数
+    /// </summary>
+    /// <remarks>用于参数无法解析或当前不需要已解析的形式的情形</remarks>
+    public class UnresolvedArgument : ICommandArgument
+    {
+        public string RawContent { get; }
+
+        public UnresolvedArgument(string rawContent)
+        {
+            if (rawContent == null)
+            {
+                throw new ArgumentNullException(nameof(rawContent));
+            }
+
+            if (rawContent.Length <= 0)
+            {
+                throw new ArgumentException($"{nameof(rawContent)} 不得为空", nameof(rawContent));
+            }
+
+            RawContent = rawContent;
+        }
+    }
+
+    /// <summary>
+    /// 命令分析器
+    /// </summary>
+    public static class CommandParser
+    {
+        /// <summary>
+        /// 分析命令
+        /// </summary>
+        /// <param name="input">输入，即作为命令被分析的文本</param>
+        /// <returns>命令名及命令的参数</returns>
+        public static (string, IList<ICommandArgument>) ParseCommand(string input)
+        {
+            if (input == null || input.Length < 2)
+            {
+                throw new ArgumentException("输入不合法", nameof(input));
+            }
+
+            var splitResult = input.Split(new[] { ' ', '\t' }, StringSplitOptions.RemoveEmptyEntries);
+            if (splitResult.Length == 0)
+            {
+                throw new ArgumentException($"输入 ({input}) 不合法");
+            }
+
+            return (splitResult[0], ParseCommandArgument(splitResult.Skip(1)));
+        }
+
+        // 参数必须保持有序，因此返回值使用 IList 而不是 IEnumerable
+        private static IList<ICommandArgument> ParseCommandArgument(IEnumerable<string> input)
+        {
+            var result = new List<ICommandArgument>();
+
+            foreach (var arg in input)
+            {
+                Contract.Assert(arg != null && arg.Length > 1);
+
+                // TODO: 使用更加具有可扩展性的方法
+                switch (arg[0])
+                {
+                    case '@':
+                        result.Add(new TargetSelectorArgument(arg));
+                        break;
+                    case '{':
+                        result.Add(new DataTagArgument(arg));
+                        break;
+                    default:
+                        result.Add(new UnresolvedArgument(arg));
+                        break;
+                }
+            }
+
+            return result;
+        }
+    }
+}

src/MineCase.Server.Interfaces/Game/Commands/DataTagArgument.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using MineCase.Nbt.Tags;
+
+namespace MineCase.Server.Game.Commands
+{
+    public class DataTagArgument : UnresolvedArgument
+    {
+        public NbtCompound Tag { get; }
+
+        public DataTagArgument(string rawContent)
+            : base(rawContent)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}

src/MineCase.Server.Interfaces/Game/Commands/ICommand.cs

@@ -0,0 +1,90 @@
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+
+namespace MineCase.Server.Game.Commands
+{
+    /// <summary>
+    /// 命令参数接口
+    /// </summary>
+    public interface ICommandArgument
+    {
+        /// <summary>
+        /// Gets 命令参数的原本内容
+        /// </summary>
+        string RawContent { get; }
+    }
+
+    /// <summary>
+    /// 命令接口
+    /// </summary>
+    public interface ICommand
+    {
+        /// <summary>
+        /// Gets 该命令的名称
+        /// </summary>
+        string Name { get; }
+
+        /// <summary>
+        /// Gets 该命令的描述，可为 null
+        /// </summary>
+        string Description { get; }
+
+        /// <summary>
+        /// Gets 要执行此命令需要的权限，可为 null
+        /// </summary>
+        Permission NeededPermission { get; }
+
+        /// <summary>
+        /// Gets 该命令的别名，可为 null
+        /// </summary>
+        IEnumerable<string> Aliases { get; }
+
+        /// <summary>
+        /// 执行该命令
+        /// </summary>
+        /// <param name="commandSender">发送命令者</param>
+        /// <param name="args">命令的参数</param>
+        /// <returns>执行是否成功，如果成功则返回 true</returns>
+        /// <exception cref="CommandException">可能抛出派生自 <see cref="CommandException"/> 的异常</exception>
+        bool Execute(ICommandSender commandSender, IList<ICommandArgument> args);
+    }
+
+    /// <summary>
+    /// 命令执行过程中可能发生的异常的基类
+    /// </summary>
+    /// <remarks>派生自此类的异常在 <see cref="CommandMap.Dispatch(ICommandSender, string)"/> 中将会被吃掉，不会传播到外部</remarks>
+    public class CommandException : Exception
+    {
+        public ICommand Command { get; }
+
+        public CommandException(ICommand command = null, string content = null, Exception innerException = null)
+            : base(content, innerException)
+        {
+            Command = command;
+        }
+    }
+
+    /// <summary>
+    /// 表示命令的使用方式错误的异常
+    /// </summary>
+    public class CommandWrongUsageException : CommandException
+    {
+        public CommandWrongUsageException(ICommand command, string content = null, Exception innerException = null)
+            : base(command, content, innerException)
+        {
+        }
+    }
+
+    /// <summary>
+    /// 可发送命令者接口
+    /// </summary>
+    public interface ICommandSender : IPermissible
+    {
+        /// <summary>
+        /// 向可发送命令者发送（一般为反馈）特定的信息
+        /// </summary>
+        /// <param name="msg">要发送的信息</param>
+        Task SendMessage(string msg);
+    }
+}

src/MineCase.Server.Interfaces/Game/SimpleCommand.cs → src/MineCase.Server.Interfaces/Game/Commands/SimpleCommand.cs

@@ -1,9 +1,12 @@
 using System;
 using System.Collections.Generic;
-using System.Text;
 
-namespace MineCase.Server.Game
+namespace MineCase.Server.Game.Commands
 {
+    /// <summary>
+    /// 简单指令
+    /// </summary>
+    /// <remarks>用于无复杂的名称、描述、权限及别名机制的指令</remarks>
     public abstract class SimpleCommand : ICommand
     {
         public string Name { get; }
@@ -27,6 +30,6 @@ protected SimpleCommand(string name, string description = null, Permission neede
             }
         }
 
-        public abstract bool Execute(ICommandSender commandSender, IEnumerable<string> args);
+        public abstract bool Execute(ICommandSender commandSender, IList<ICommandArgument> args);
     }
 }