diff --git a/src/container/list/list.go b/src/container/list/list.go index dc4260e131..b8b599aabb 100644 --- a/src/container/list/list.go +++ b/src/container/list/list.go @@ -116,6 +116,23 @@ func (l *List) remove(e *Element) *Element { return e } +// move moves e to next to at and returns e. +func (l *List) move(e, at *Element) *Element { + if e == at { + return e + } + e.prev.next = e.next + e.next.prev = e.prev + + n := at.next + at.next = e + e.prev = at + e.next = n + n.prev = e + + return e +} + // Remove removes e from l if e is an element of list l. // It returns the element value e.Value. // The element must not be nil. @@ -170,7 +187,7 @@ func (l *List) MoveToFront(e *Element) { return } // see comment in List.Remove about initialization of l - l.insert(l.remove(e), &l.root) + l.move(e, &l.root) } // MoveToBack moves element e to the back of list l. @@ -181,7 +198,7 @@ func (l *List) MoveToBack(e *Element) { return } // see comment in List.Remove about initialization of l - l.insert(l.remove(e), l.root.prev) + l.move(e, l.root.prev) } // MoveBefore moves element e to its new position before mark. @@ -191,7 +208,7 @@ func (l *List) MoveBefore(e, mark *Element) { if e.list != l || e == mark || mark.list != l { return } - l.insert(l.remove(e), mark.prev) + l.move(e, mark.prev) } // MoveAfter moves element e to its new position after mark. @@ -201,7 +218,7 @@ func (l *List) MoveAfter(e, mark *Element) { if e.list != l || e == mark || mark.list != l { return } - l.insert(l.remove(e), mark) + l.move(e, mark) } // PushBackList inserts a copy of an other list at the back of list l.