public override IValue interpret(Context context)
{
IType sourceType = source.check(context);
if (!(sourceType is IterableType))
{
throw new InternalError("Illegal source type: " + sourceType.GetTypeName());
}
IType itemType = ((IterableType)sourceType).GetItemType();
IValue value = source.interpret(context);
if (value == null)
{
throw new NullReferenceError();
}
if (!(value is IFilterable))
{
throw new InternalError("Illegal fetch source: " + source);
}
IFilterable list = (IFilterable)value;
ArrowExpression arrow = predicate.ToArrowExpression();
Predicate <IValue> filter = arrow.GetFilter(context, itemType);
return(list.Filter(filter));
}
IValue interpretPredicate(Context context)
{
IValue lval = left.interpret(context);
if (lval is IContainer)
{
IType itemType = ((ContainerType)lval.GetIType()).GetItemType();
ArrowExpression arrow = ((PredicateExpression)right).ToArrowExpression();
Predicate <IValue> predicate = arrow.GetFilter(context, itemType);
return(interpretPredicate(context, (IContainer)lval, predicate));
}
else
{
throw new SyntaxError("Expecting collection");
}
}