public object Apply(ProcedureNode procedure, IList<object> arguments, Environment environment)
{
if (arguments.Count != procedure.Parameters.Count() && !procedure.Parameters.Select(x => x.Name).Contains("&"))
{
throw new ArgumentException("Wrong number of arguments given to procedure! Expected: " + procedure.Parameters.Count());
}
var localEnv = procedure.Environment.CreateChildEnvironment();
for (int i = 0; i < procedure.Parameters.Count(); ++i)
{
object evaluatedArgument;
bool finished = false;
var parameterSymbol = procedure.Parameters.ElementAt(i);
if (parameterSymbol.Name == "&")
{
parameterSymbol = procedure.Parameters.ElementAt(i + 1);
evaluatedArgument =
procedure.IsMacro ? arguments.Skip(i).ToList()
: arguments.Skip(i).Select(arg => evaluator.Evaluate(arg, environment)).ToList();
localEnv.DefineSymbol(parameterSymbol, evaluatedArgument);
finished = true;
}
else
{
evaluatedArgument =
procedure.IsMacro
? arguments.ElementAt(i)
: evaluator.Evaluate(arguments.ElementAt(i), environment);
}
localEnv.DefineSymbol(parameterSymbol, evaluatedArgument);
if (finished)
{
break;
}
}
var res = evaluator.Evaluate(procedure.Body, localEnv);
if (procedure.IsMacro)
{
return evaluator.Evaluate(res, environment);
}
return res;
}
private void PrettyPrintSub(ProcedureNode node)
{
stringWriter.Write("<procedure: " + node.Symbol + ">");
}
public object ApplyDefMacro(IList<object> arguments, Environment environment)
{
if (arguments.Count != 3)
{
throw new ArgumentException("Wrong number of arguments given to defmacro! Expected: " + 3);
}
var symbol = arguments.ElementAt(0) as SymbolNode;
if (symbol == null)
{
throw new ArgumentException("First argument to defmacro not a symbol!");
}
var parameterList = arguments.ElementAt(1) as IList<object>;
if (parameterList == null)
{
throw new ArgumentException("Second argument to defmacro not a parameterlist!");
}
var body = arguments.ElementAt(2);
var macro = new ProcedureNode(parameterList.Cast<SymbolNode>(), new[] { body }, environment.CreateChildEnvironment(), true);
environment.DefineSymbol(symbol, macro);
return symbol;
}
