linked-list-iterator and context operator $$ enhancement

linked-list-iterator.go

@@ -13,59 +13,23 @@ import (
 )
 
 type LinkedListIterator struct {
-	a     *kern.ListType
-	count int64
-	index int64
-	start int64
-	stop  int64
-	step  int64
+	a       *kern.LinkedList
+	count   int64
+	index   int64
+	current *kern.ListNode
 }
 
-func NewLinkedListIterator(list *kern.ListType, args []any) (it *LinkedListIterator) {
-	var argc int = 0
-	listLen := int64(len(([]any)(*list)))
-	if args != nil {
-		argc = len(args)
-	}
-	it = &LinkedListIterator{a: list, count: 0, index: -1, start: 0, stop: listLen - 1, step: 1}
-	if argc >= 1 {
-		if i, err := kern.ToGoInt64(args[0], "start index"); err == nil {
-			if i < 0 {
-				i = listLen + i
-			}
-			it.start = i
-		}
-		if argc >= 2 {
-			if i, err := kern.ToGoInt64(args[1], "stop index"); err == nil {
-				if i < 0 {
-					i = listLen + i
-				}
-				it.stop = i
-			}
-			if argc >= 3 {
-				if i, err := kern.ToGoInt64(args[2], "step"); err == nil {
-					if i < 0 {
-						i = -i
-					}
-					if it.start > it.stop {
-						it.step = -i
-					} else {
-						it.step = i
-					}
-				}
-			}
-		}
-	}
-	it.index = it.start - it.step
+func NewLinkedListIterator(list *kern.LinkedList, args []any) (it *LinkedListIterator) {
+	it = &LinkedListIterator{a: list, count: 0, index: -1, current: list.FirstNode()}
 	return
 }
 
 func (it *LinkedListIterator) String() string {
 	var l = int64(0)
 	if it.a != nil {
-		l = int64(len(*it.a))
+		l = int64(it.a.Len())
 	}
-	return fmt.Sprintf("$([#%d])", l)
+	return fmt.Sprintf("$([<#%d>])", l)
 }
 
 func (it *LinkedListIterator) TypeName() string {
@@ -73,7 +37,6 @@ func (it *LinkedListIterator) TypeName() string {
 }
 
 func (it *LinkedListIterator) HasOperation(name string) bool {
-	//yes := name == expr.NextName || name == expr.ResetName || name == expr.IndexName || name == expr.CountName || name == expr.CurrentName
 	yes := slices.Contains([]string{kern.NextName, kern.ResetName, kern.IndexName, kern.CountName, kern.CurrentName}, name)
 	return yes
 }
@@ -99,28 +62,22 @@ func (it *LinkedListIterator) CallOperation(name string, args map[string]any) (v
 }
 
 func (it *LinkedListIterator) Current() (item any, err error) {
-	a := *(it.a)
-	if it.start <= it.stop {
-		if it.stop < int64(len(a)) && it.index >= it.start && it.index <= it.stop {
-			item = a[it.index]
-		} else {
-			err = io.EOF
-		}
+	if it.current != nil {
+		item = it.current.Data()
 	} else {
-		if it.start < int64(len(a)) && it.index >= it.stop && it.index <= it.start {
-			item = a[it.index]
-		} else {
-			err = io.EOF
-		}
-
+		err = io.EOF
 	}
 	return
 }
 
 func (it *LinkedListIterator) Next() (item any, err error) {
-	it.index += it.step
-	if item, err = it.Current(); err != io.EOF {
+	if it.current != nil {
+		item = it.current.Data()
+		it.current = it.current.Next()
+		it.index++
 		it.count++
+	} else {
+		err = io.EOF
 	}
 	return
 }
@@ -134,7 +91,8 @@ func (it *LinkedListIterator) Count() int64 {
 }
 
 func (it *LinkedListIterator) Reset() error {
-	it.index = it.start - it.step
+	it.current = it.a.FirstNode()
+	it.index = -1
 	it.count = 0
 	return nil
 }