update golang linkedlist

Author: nange

go/linkedlist/linkedlist.go

@@ -0,0 +1,144 @@
+package linkedlist
+
+type Lister interface {
+	Clear()
+	Len() int
+	Front() *Element
+	Back() *Element
+	Remove(e *Element) interface{}
+	PushFront(v interface{}) *Element
+	PushBack(v interface{}) *Element
+	InsertBefore(v interface{}, mark *Element) *Element
+	InsertAfter(v interface{}, mark *Element) *Element
+	MoveBefore(e, mark *Element)
+	MoveAfter(e, mark *Element)
+}
+
+type Element struct {
+	prev, next *Element
+	list       *List
+	Value      interface{}
+}
+
+func (e *Element) Next() *Element {
+	if n := e.next; n != nil && n != &e.list.root {
+		return n
+	}
+	return nil
+}
+
+func (e *Element) Prev() *Element {
+	if p := e.prev; p != nil && p != &e.list.root {
+		return p
+	}
+	return nil
+}
+
+type List struct {
+	root Element
+	len  int
+}
+
+func New() *List {
+	l := new(List)
+	l.Clear()
+	return l
+}
+
+func (l *List) Clear() {
+	if firstElem := l.root.next; firstElem != nil && firstElem.list == l {
+		firstElem.prev = nil
+	}
+	if lastElem := l.root.prev; lastElem != nil && lastElem.list == l {
+		lastElem.next = nil
+	}
+	l.root.next = &l.root
+	l.root.prev = &l.root
+	l.len = 0
+}
+
+func (l *List) Len() int {
+	return l.len
+}
+
+func (l *List) Front() *Element {
+	if l.len == 0 {
+		return nil
+	}
+	return l.root.next
+}
+
+func (l *List) Back() *Element {
+	if l.len == 0 {
+		return nil
+	}
+	return l.root.prev
+}
+
+func (l *List) remove(e *Element) *Element {
+	e.prev.next = e.next
+	e.next.prev = e.prev
+	e.prev = nil
+	e.next = nil
+	e.list = nil
+	l.len--
+	return e
+}
+
+func (l *List) Remove(e *Element) interface{} {
+	if e.list == l {
+		l.remove(e)
+	}
+	return e.Value
+}
+
+func (l *List) insert(e, at *Element) *Element {
+	n := at.next
+	at.next = e
+	e.prev = at
+	e.next = n
+	n.prev = e
+	e.list = l
+	l.len++
+	return e
+}
+
+func (l *List) insertValue(v interface{}, at *Element) *Element {
+	return l.insert(&Element{Value: v}, at)
+}
+
+func (l *List) PushFront(v interface{}) *Element {
+	return l.insertValue(v, &l.root)
+}
+
+func (l *List) PushBack(v interface{}) *Element {
+	return l.insertValue(v, l.root.prev)
+}
+
+func (l *List) InsertBefore(v interface{}, mark *Element) *Element {
+	if mark.list != l {
+		return nil
+	}
+	return l.insertValue(v, mark.prev)
+}
+
+func (l *List) InsertAfter(v interface{}, mark *Element) *Element {
+	if mark.list != l {
+		return nil
+	}
+	return l.insertValue(v, mark)
+}
+
+func (l *List) MoveBefore(e, mark *Element) {
+	if e.list != l || mark.list != l || e == mark {
+		return
+	}
+	l.insert(l.remove(e), mark.prev)
+}
+
+func (l *List) MoveAfter(e, mark *Element) {
+	if e.list != l || mark.list != l || e == mark {
+		return
+	}
+	l.insert(l.remove(e), mark)
+}