builtin-iterator.go: added supporto to automatic variables $_ (iterator index) and $__ (iterator item)

builtin-iterator.go

@@ -92,13 +92,23 @@ func runFunc(ctx kern.ExprContext, name string, args map[string]any) (result any
 			// params = map[string]any{kern.ParamIndex: it.Index(), kern.ParamItem: item}
 			params[kern.ParamIndex] = it.Index()
 			params[kern.ParamItem] = item
+
+			localCtx.UnsafeSetVar("_", it.Index())
+			localCtx.UnsafeSetVar("__", item)
+
+			abort := false
 			if _, err = op.InvokeNamed(localCtx, iterParamOperator, params); err != nil {
-				break
+				abort = true
 			} else if abortAny, exists := localCtx.GetVar(iterVarAbort); exists {
 				if abort, ok := boolean.ToBool(abortAny); ok && abort {
-					break
+					abort = true
 				}
 			}
+			localCtx.DeleteVar("__")
+			localCtx.DeleteVar("_")
+			if abort {
+				break
+			}
 		}
 	}