static void Run() { while (true) { // Take user input string _input = ReadLine(); // Ignore if input is empty if (string.IsNullOrWhiteSpace(_input)) { continue; } // Attempt to parse input try { ShellCommand command = new ShellCommand(_input); string result = Execute(command); WriteLine(result); } catch (Exception ex) { WriteLine("EXCEPTION: " + ex); } } }
static string Execute(ShellCommand command) { // Validate the command name: if (!_commandLibraries.ContainsKey(command.LibraryClassName)) { return(BadCommandMessage(command)); } var methodDictionary = _commandLibraries[command.LibraryClassName]; if (!methodDictionary.ContainsKey(command.Name)) { return(BadCommandMessage(command)); } // Make sure the corret number of required arguments are provided: // +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ var methodParameterValueList = new List <object>(); IEnumerable <ParameterInfo> paramInfoList = methodDictionary[command.Name].ToList(); // Validate proper # of required arguments provided. Some may be optional: var requiredParams = paramInfoList.Where(p => p.IsOptional == false); var optionalParams = paramInfoList.Where(p => p.IsOptional == true); int requiredCount = requiredParams.Count(); int optionalCount = optionalParams.Count(); int providedCount = command.Arguments.Count(); if (requiredCount > providedCount) { return(string.Format( "Missing required argument. {0} required, {1} optional, {2} provided", requiredCount, optionalCount, providedCount)); } if (providedCount > (requiredCount + optionalCount)) { return(string.Format( "Too many arguments provided. {0} required, {1} optional, {2} provided", requiredCount, optionalCount, providedCount)); } // Make sure all arguments are coerced to the proper type, and that there is a // value for every emthod parameter. The InvokeMember method fails if the number // of arguments provided does not match the number of parameters in the // method signature, even if some are optional: // +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ if (paramInfoList.Count() > 0) { // Populate the list with default values: foreach (var param in paramInfoList) { // This will either add a null object reference if the param is required // by the method, or will set a default value for optional parameters. in // any case, there will be a value or null for each method argument // in the method signature: methodParameterValueList.Add(param.DefaultValue); } // Now walk through all the arguments passed from the console and assign // accordingly. Any optional arguments not provided have already been set to // the default specified by the method signature: for (int i = 0; i < command.Arguments.Count(); i++) { var methodParam = paramInfoList.ElementAt(i); var typeRequired = methodParam.ParameterType; object value = null; try { // Coming from the Console, all of our arguments are passed in as // strings. Coerce to the type to match the method paramter: value = CoerceArgument(typeRequired, command.Arguments.ElementAt(i)); methodParameterValueList.RemoveAt(i); methodParameterValueList.Insert(i, value); } catch (ArgumentException) { string argumentName = methodParam.Name; string argumentTypeName = typeRequired.Name; string message = string.Format("" + "The value passed for argument '{0}' cannot be parsed to type '{1}'", argumentName, argumentTypeName); throw new ArgumentException(message); } } } // Set up to invoke the method using reflection: // +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Assembly current = typeof(Program).Assembly; // Need the full Namespace for this: Type commandLibaryClass = current.GetType(_commandNamespace + "." + command.LibraryClassName); object[] inputArgs = null; if (methodParameterValueList.Count > 0) { inputArgs = methodParameterValueList.ToArray(); } var typeInfo = commandLibaryClass; // This will throw if the number of arguments provided does not match the number // required by the method signature, even if some are optional: try { var result = typeInfo.InvokeMember( command.Name, BindingFlags.InvokeMethod | BindingFlags.Static | BindingFlags.Public, null, null, inputArgs); try { return(result.ToString()); } catch (NullReferenceException) { // Return an empty string on null response from function return(""); } } catch (TargetInvocationException ex) { throw ex.InnerException; } }
static string BadCommandMessage(ShellCommand command = null) { // TODO: Update message to include command return(string.Format("Command does not exist.")); }