int-iterator: fixed iterator's index value

int-iterator.go

@@ -15,11 +15,13 @@ import (
 )
 
 type IntIterator struct {
-	count int64
-	index int64
-	start int64
-	stop  int64
-	step  int64
+	count   int64
+	index   int64
+	next    int64
+	current any
+	start   int64
+	stop    int64
+	step    int64
 }
 
 func NewIntIteratorFromInterval(p *interval.IntervalType) (it *IntIterator, err error) {
@@ -110,26 +112,23 @@ func (it *IntIterator) CallOperation(name string, args map[string]any) (v any, e
 }
 
 func (it *IntIterator) Current() (item any, err error) {
-	if it.start <= it.stop {
-		if it.index >= it.start && it.index < it.stop {
-			item = it.index
-		} else {
-			err = io.EOF
-		}
-	} else {
-		if it.index > it.stop && it.index <= it.start {
-			item = it.index
-		} else {
-			err = io.EOF
-		}
-	}
-	return
+	return it.current, nil
 }
 
 func (it *IntIterator) Next() (item any, err error) {
-	it.index += it.step
-	if item, err = it.Current(); err != io.EOF {
+	item = it.next
+	if it.step > 0 {
+		if it.next+it.step > it.stop {
+			err = io.EOF
+		}
+	} else if it.next+it.step < it.stop {
+		err = io.EOF
+	}
+	if err == nil {
+		it.index++
 		it.count++
+		it.next += it.step
+		it.current = item
 	}
 	return
 }
@@ -143,7 +142,9 @@ func (it *IntIterator) Count() int64 {
 }
 
 func (it *IntIterator) Reset() error {
-	it.index = it.start - it.step
+	it.index = -1
+	it.next = it.start
+	it.current = nil
 	it.count = 0
 	return nil
 }