Merge pull request #9805 from pacien/181126-list-append

add SinglyLinkedList.append procs

lib/pure/collections/lists.nim

@@ -140,11 +140,26 @@ proc contains*[T](L: SomeLinkedCollection[T], value: T): bool {.inline.} =
   ## exist, true otherwise.
   result = find(L, value) != nil
 
+proc append*[T](L: var SinglyLinkedList[T],
+                n: SinglyLinkedNode[T]) {.inline.} =
+  ## appends a node `n` to `L`. Efficiency: O(1).
+  n.next = nil
+  if L.tail != nil:
+    assert(L.tail.next == nil)
+    L.tail.next = n
+  L.tail = n
+  if L.head == nil: L.head = n
+
+proc append*[T](L: var SinglyLinkedList[T], value: T) {.inline.} =
+  ## appends a value to `L`. Efficiency: O(1).
+  append(L, newSinglyLinkedNode(value))
+
 proc prepend*[T](L: var SinglyLinkedList[T],
                  n: SinglyLinkedNode[T]) {.inline.} =
   ## prepends a node to `L`. Efficiency: O(1).
   n.next = L.head
   L.head = n
+  if L.tail == nil: L.tail = n
 
 proc prepend*[T](L: var SinglyLinkedList[T], value: T) {.inline.} =
   ## prepends a node to `L`. Efficiency: O(1).

tests/stdlib/tlists.nim

@@ -10,7 +10,8 @@ const
 block SinglyLinkedListTest1:
   var L: SinglyLinkedList[int]
   for d in items(data): L.prepend(d)
-  assert($L == "[6, 5, 4, 3, 2, 1]")
+  for d in items(data): L.append(d)
+  assert($L == "[6, 5, 4, 3, 2, 1, 1, 2, 3, 4, 5, 6]")
 
   assert(4 in L)