Iterator: new function Count()

data-cursor.go

@@ -10,30 +10,30 @@ import (
 )
 
 type dataCursor struct {
-	ds          map[string]Functor
-	ctx         ExprContext
-	index       int
-	current any
-	lastErr error
-	resource    any
-	nextFunc    Functor
-	cleanFunc   Functor
-	resetFunc   Functor
-//	currentFunc Functor
+	ds        map[string]Functor
+	ctx       ExprContext
+	index     int
+	count     int
+	current   any
+	lastErr   error
+	resource  any
+	nextFunc  Functor
+	cleanFunc Functor
+	resetFunc Functor
 }
 
 func NewDataCursor(ctx ExprContext, ds map[string]Functor, resource any) (dc *dataCursor) {
 	dc = &dataCursor{
-		ds:          ds,
-		index:       -1,
-		current: nil,
-		lastErr: nil,
-		resource:    resource,
-		ctx:         ctx.Clone(),
-		nextFunc:    ds[NextName],
-//		currentFunc: ds[CurrentName],
-		cleanFunc:   ds[CleanName],
-		resetFunc:   ds[ResetName],
+		ds:       ds,
+		index:    -1,
+		count:    0,
+		current:  nil,
+		lastErr:  nil,
+		resource: resource,
+		ctx:      ctx.Clone(),
+		nextFunc: ds[NextName],
+		cleanFunc: ds[CleanName],
+		resetFunc: ds[ResetName],
 	}
 	dc.Next()
 	return
@@ -109,6 +109,7 @@ func (dc *dataCursor) Reset() (success bool, err error) {
 			ctx := cloneContext(dc.ctx)
 			if _, err = dc.resetFunc.Invoke(ctx, ResetName, []any{dc.resource}); err == nil {
 				dc.index = -1
+				dc.count = 0
 			}
 			exportObjects(dc.ctx, ctx)
 			dc.Next()
@@ -167,7 +168,6 @@ func (dc *dataCursor) mapItem(mapper Functor, item any) (mappedItem any, err err
 }
 
 func (dc *dataCursor) Next() (current any, err error) { // must return io.EOF after the last item
-	var accepted bool
 	if err = dc.lastErr; err != nil {
 		return
 	}
@@ -179,15 +179,19 @@ func (dc *dataCursor) Next() (current any, err error) { // must return io.EOF af
 		for item == nil && dc.lastErr == nil {
 			ctx := cloneContext(dc.ctx)
 			dc.index++
-			if item, dc.lastErr  = dc.nextFunc.Invoke(ctx, NextName, []any{dc.resource, dc.index}); dc.lastErr == nil {
+			if item, dc.lastErr = dc.nextFunc.Invoke(ctx, NextName, []any{dc.resource, dc.index}); dc.lastErr == nil {
 				if item == nil {
 					dc.lastErr = io.EOF
 				} else {
+					accepted := true
 					if filter != nil {
 						if accepted, dc.lastErr = dc.checkFilter(filter, item); dc.lastErr != nil || !accepted {
 							item = nil
 						}
 					}
+					if accepted {
+						dc.count++
+					}
 					if item != nil && mapper != nil {
 						item, dc.lastErr = dc.mapItem(mapper, item)
 					}
@@ -197,6 +201,7 @@ func (dc *dataCursor) Next() (current any, err error) { // must return io.EOF af
 		}
 		dc.current = item
 		if dc.lastErr != nil {
+			dc.index--
 			dc.Clean()
 		}
 	} else {
@@ -206,5 +211,10 @@ func (dc *dataCursor) Next() (current any, err error) { // must return io.EOF af
 }
 
 func (dc *dataCursor) Index() int {
-	return dc.index-1
+	return dc.index - 1
+}
+
+
+func (dc *dataCursor) Count() int {
+	return dc.count
 }