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."));
}
