private static void Run()
{
while (true)
{
var consoleInput = ReadFromConsole();
if (string.IsNullOrWhiteSpace(consoleInput)) continue;
if (consoleInput.ToLower() == "exit") break;
try
{
// Create a ConsoleCommand instance:
var cmd = new ConsoleCommand(consoleInput);
// Execute the command:
string result = Execute(cmd);
// Write out the result:
WriteToConsole(result);
}
catch (Exception ex)
{
// OOPS! Something went wrong - Write out the problem:
WriteToConsole(ex.Message);
}
}
}
private static string Execute(ConsoleCommand command)
{
// Validate the class name and command name:
// +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
string badCommandMessage = string.Format("Unrecognized command \'{0}.{1}\'. Please type a valid command.", command.LibraryClassName, command.Name);
// Validate the command name:
if (!Library.Commands.ContainsKey(command.LibraryClassName))
{
return badCommandMessage;
}
var methodDictionary = Library.Commands[command.LibraryClassName];
if (!methodDictionary.ContainsKey(command.Name))
{
return badCommandMessage;
}
// 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);
var requiredCount = requiredParams.Count();
var optionalCount = optionalParams.Count();
var providedCount = command.Arguments.Count();
if (requiredCount > providedCount)
{
return string.Format(
"Missing required argument. {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.Any())
{
// 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 (var i = 0; i < command.Arguments.Count(); i++)
{
var methodParam = paramInfoList.ElementAt(i);
var typeRequired = methodParam.ParameterType;
try
{
// Coming from the Console, all of our arguments are passed in as
// strings. Coerce to the type to match the method paramter:
var value = CoerceArgument(typeRequired, command.Arguments.ElementAt(i));
methodParameterValueList.RemoveAt(i);
methodParameterValueList.Insert(i, value);
}
catch (ArgumentException)
{
var argumentName = methodParam.Name;
var argumentTypeName = typeRequired.Name;
var 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:
// +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
var current = typeof (Program).Assembly;
// Need the full Namespace for this:
var commandLibaryClass = current.GetType(Library.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);
return result.ToString();
}
catch (TargetInvocationException ex)
{
throw ex.InnerException;
}
}