public Continuation Perform(Continuation c)
{
var args = new Datum[argCount];
for (var i = 0; i < argCount; ++i)
{
args[i] = c.Result;
c = c.PopResult();
}
return(function.Evaluate(c, DatumHelpers.compound(args)));
}
public override Continuation Evaluate(Continuation c, Datum args)
{
var argArray = args.ToArray();
if (argArray.Length != 2)
{
throw DatumHelpers.error("Invalid syntax. ArgCount ({0}) != 2. Usage: (execute-with-error-handler <error-function> <fn>)", argArray.Length);
}
var errorHandler = makeErrorHandler(c.ErrorHandler, (StackFunction)argArray[0]);
var fn = (StackFunction)argArray[1];
return(fn.Evaluate(c.NewErrorHandler(errorHandler), DatumHelpers.compound()));
}
public override Continuation Evaluate(Continuation c, Datum args)
{
var argArray = args.ToArray();
if (argArray.Length != 1)
{
throw DatumHelpers.error("call/cc: expect a single function as an argument. Got {0}", argArray.Length);
}
var arg = argArray[0];
var function = arg as StackFunction;
if (function == null)
{
throw DatumHelpers.error("call/cc: {0} must be a function", arg);
}
return(function.Evaluate(c, DatumHelpers.compound(new ContinuationFunction(c))));
}
private static ErrorHandler makeErrorHandler(ErrorHandler oldErrorHandler, StackFunction f)
{
// Report the "message" from the exception to the Lisp
// error handling function.
// Ensure that the original error handler is in scope before evaluating the error function -
// otherwise we end up in an infinite loop if there's an error in the error function itself.
return((c, ex) => f.Evaluate(c.PopTask().SetErrorHandler(oldErrorHandler), DatumHelpers.compound(ex.Message.ToAtom(), CallCC.MakeContinuationFunction(c))));
}