new iter-iter iterator and kern.func-info module

iter-factory.go

@@ -5,10 +5,13 @@
 package expr
 
 import (
+	"fmt"
+	"slices"
+
 	"git.portale-stac.it/go-pkg/expr/kern"
 )
 
-func NewIterator(value any) (it kern.Iterator, err error) {
+func NewIterator(ctx kern.ExprContext, value any, args map[string]any) (it kern.Iterator, err error) {
 	if value == nil {
 		return NewArrayIterator([]any{}), nil
 	}
@@ -21,9 +24,24 @@ func NewIterator(value any) (it kern.Iterator, err error) {
 	case []any:
 		it = NewArrayIterator(v)
 	case kern.Iterator:
-		it = v
+		// it = v
+		var op kern.Functor
+		if len(args) >= 1 {
+			if opArg, ok := args["op"]; ok {
+				if op, ok = opArg.(kern.Functor); !ok {
+					err = fmt.Errorf("the 'op' argument must be a kern.Functor, got %T", opArg)
+				}
+			}
+		}
+		if err == nil {
+			it, err = NewIterIter(v, ctx, op, args)
+		}
 	default:
 		it = NewArrayIterator([]any{value})
 	}
 	return
 }
+
+func HasStandardOperation(name string) bool {
+	return slices.Contains([]string{kern.NextName, kern.ResetName, kern.IndexName, kern.CountName, kern.CurrentName, kern.CleanName}, name)
+}