public object Eval(SExpr sexpr, ExternEvaluate customEval)
{
if (customEval == null)
{
customEval = defaultEval;
}
sexpr.ThrowIfError();
if (sexpr.Kind == SExprKind.ScopedIdentifier)
{
// Try to resolve the identifier:
var identExpr = (ScopedIdentifierExpr)sexpr;
NamedStorage variable = TryResolve(identExpr);
if (variable == null)
{
throw new Exception("Cannot find variable named '{0}' in scope".F(identExpr.Name));
}
return(variable.Value);
}
else if (sexpr.Kind == SExprKind.Invocation)
{
return(Invoke((InvocationExpr)sexpr));
}
else if (sexpr.Kind == SExprKind.List)
{
var le = (ListExpr)sexpr;
var items = new object[le.Count];
for (int i = 0; i < items.Length; ++i)
{
items[i] = customEval(this, le[i], customEval);
}
return(items);
}
else if (sexpr.Kind == SExprKind.Quote)
{
return(sexpr);
}
else if (sexpr.Kind == SExprKind.Integer)
{
return(((IntegerExpr)sexpr).Value);
}
else if (sexpr.Kind == SExprKind.Boolean)
{
return(((BooleanExpr)sexpr).Value);
}
else if (sexpr.Kind == SExprKind.Null)
{
return(null);
}
else if (sexpr.Kind == SExprKind.String)
{
return(sexpr.StartToken.Text);
}
else if (sexpr.Kind == SExprKind.Decimal)
{
return(((DecimalExpr)sexpr).Value);
}
else if (sexpr.Kind == SExprKind.Double)
{
return(((DoubleExpr)sexpr).Value);
}
else if (sexpr.Kind == SExprKind.Float)
{
return(((FloatExpr)sexpr).Value);
}
throw new Exception("Unknown expression kind: '{0}'".F(sexpr.Kind));
}
