private static IExpression QuotationSpecialFormParser <T> (IExpression expression, Func <IExpression, T> creator)
where T : IExpression
{
var combination = expression as ScmCombination;
if (!combination.Operands.IsSingle())
{
throw new ParserException(UserMessages.MustContainOneExpressionAsArgument, combination);
}
var datum = ParseExpression(combination.Operands.First());
if (datum is ScmCombination)
{
var datumAsCombination = datum as ScmCombination;
if (datumAsCombination.Expressions.IsEmpty())
{
datum = ScmEmptyList.Instance;
}
else
{
datum = new ScmPair(datumAsCombination.Expressions);
}
}
var quoteSpecialForm = creator(datum);
return(quoteSpecialForm);
}
private Bounce ApplyClosureProcedure(ScmCombination combination, Environment env, Cont cont)
{
//((lambda (b . a) a) 1)
var closure = combination.Procedure as ScmClosure;
var numberOfArguments = closure.ArgumentList.Count;
var operands = new List <IExpression> (combination.Operands);
if (!closure.Dotted && numberOfArguments != operands.Count)
{
throw new EvaluatorException(String.Format("Expecting {0} argument{1}", numberOfArguments, numberOfArguments > 1 ? "s" : ""), combination);
}
else if (closure.Dotted)
{
var numberOfArgumentsButLast = numberOfArguments - 1;
if (numberOfArgumentsButLast > operands.Count)
{
throw new EvaluatorException(String.Format("Expecting at least {0} argument{1}", numberOfArgumentsButLast, numberOfArgumentsButLast > 1 ? "s" : ""), combination);
}
else if (numberOfArgumentsButLast == operands.Count)
{
operands.Add(ScmEmptyList.Instance);
}
else
{
var lastArgument = new ScmPair(operands.TailFrom(numberOfArgumentsButLast));
operands = new List <IExpression> (operands.GetRange(0, numberOfArgumentsButLast));
operands.Add(lastArgument);
}
}
return(() => EvalList(operands, env, evalResults =>
{
var environmentFrame = new EnvironmentFrame();
var evalResultsAsList = evalResults as List <IExpression>;
for (int i = 0; i < closure.ArgumentList.Count; ++i)
{
var argumentName = closure.ArgumentList[i];
var argumentValue = evalResultsAsList[i];
environmentFrame.Set(argumentName, argumentValue);
}
var newEnvironment = (new Environment(closure.Env)).Extend(environmentFrame);
return EvalList(closure.Body.AllButLast(), newEnvironment, bodyEvalResults =>
{
return Eval(closure.Body.Last(), newEnvironment, cont);
});
}));
}
public ScmPair(List <IExpression> list)
{
System.Diagnostics.Debug.Assert(list != null && list.Count > 0);
ScmPair currPair = this;
for (int i = 0; i < list.Count; ++i)
{
currPair.Car = list[i];
if (i < list.Count - 1)
{
currPair.Cdr = new ScmPair();
currPair = (ScmPair)currPair.Cdr;
}
else
{
currPair.Cdr = ScmEmptyList.Instance;
}
}
}
