got rid of some arcane module names

lib/pure/collections/lists.nim

@@ -0,0 +1,155 @@
+#
+#
+#            Nimrod's Runtime Library
+#        (c) Copyright 2011 Andreas Rumpf
+#
+#    See the file "copying.txt", included in this
+#    distribution, for details about the copyright.
+#
+
+## Implementation of singly and doubly linked lists. Because it makes no sense
+## to do so, the 'next' and 'prev' pointers are not hidden from you and can
+## be manipulated directly for efficiency.
+
+type
+  TDoublyLinkedNode[T] {.pure, final.} = object
+    next*, prev*: ref TDoublyLinkedNode[T]
+    value*: T
+  PDoublyLinkedNode*[T] = ref TDoublyLinkedNode[T]
+
+  TSinglyLinkedNode[T] {.pure, final.} = object
+    next*: ref TSinglyLinkedNode[T]
+    value*: T
+  PSinglyLinkedNode*[T] = ref TSinglyLinkedNode[T]
+
+proc newDoublyLinkedNode*[T](value: T): PDoublyLinkedNode[T] =
+  ## creates a new doubly linked node with the given `value`.
+  new(result)
+  result.value = value
+
+proc newSinglyLinkedNode*[T](value: T): PSinglyLinkedNode[T] =
+  ## creates a new singly linked node with the given `value`.
+  new(result)
+  result.value = value
+
+iterator items*[T](n: PDoublyLinkedNode[T]): T = 
+  ## yields every value of `x`.
+  var it = n
+  while it != nil:
+    yield it.value
+    it = it.next
+
+iterator items*[T](n: PSinglyLinkedNode[T]): T = 
+  ## yields every value of `x`.
+  var it = n
+  while it != nil:
+    yield it.value
+    it = it.next
+
+iterator nodes*[T](n: PSinglyLinkedNode[T]): PSinglyLinkedNode[T] = 
+  ## iterates over every node of `x`. Removing the current node from the
+  ## list during traversal is supported.
+  var it = n
+  while it != nil:
+    var nxt = it.next
+    yield it
+    it = nxt
+
+iterator nodes*[T](n: PDoublyLinkedNode[T]): PDoublyLinkedNode[T] = 
+  ## iterates over every node of `x`. Removing the current node from the
+  ## list during traversal is supported.
+  var it = n
+  while it != nil:
+    var nxt = it.next
+    yield it
+    it = nxt
+
+proc `$`*[list: PSinglyLinkedNode|PDoublyLinkedNode](n: list): string = 
+  ## turns a list into its string representation.
+  result = "["
+  for x in nodes(n):
+    if result.len > 1: result.add(", ")
+    result.add($x.value)
+  result.add("]")
+
+proc find*[list: PSinglyLinkedNode|PDoublyLinkedNode, T](
+           n: list, value: T): list = 
+  ## searches in the list for a value. Returns nil if the value does not
+  ## exist.
+  for x in nodes(n):
+    if x.value == value: return x
+
+proc contains*[list: PSinglyLinkedNode|PDoublyLinkedNode, T](
+           n: list, value: T): list = 
+  ## searches in the list for a value. Returns false if the value does not
+  ## exist, true otherwise.
+  for x in nodes(n):
+    if x.value == value: return true
+
+proc prepend*[T](head: var PSinglyLinkedNode[T], 
+                 toAdd: PSinglyLinkedNode[T]) {.inline.} = 
+  ## prepends a node to `head`. Efficiency: O(1).
+  toAdd.next = head
+  head = toAdd
+
+proc prepend*[T](head: var PSinglyLinkedNode[T], x: T) {.inline.} = 
+  ## creates a new node with the value `x` and prepends that node to `head`.
+  ## Efficiency: O(1).
+  preprend(head, newSinglyLinkedNode(x))
+
+proc append*[T](head: var PSinglyLinkedNode[T], 
+                toAdd: PSinglyLinkedNode[T]) = 
+  ## appends a node to `head`. Efficiency: O(n).
+  if head == nil:
+    head = toAdd
+  else:
+    var it = head
+    while it.next != nil: it = it.next
+    it.next = toAdd
+
+proc append*[T](head: var PSinglyLinkedNode[T], x: T) {.inline.} = 
+  ## creates a new node with the value `x` and appends that node to `head`.
+  ## Efficiency: O(n).
+  append(head, newSinglyLinkedNode(x))
+
+
+proc prepend*[T](head: var PDoublyLinkedNode[T], 
+                 toAdd: PDoublyLinkedNode[T]) {.inline.} = 
+  ## prepends a node to `head`. Efficiency: O(1).
+  if head == nil:
+    head = toAdd
+    # head.prev stores the last node:
+    head.prev = toAdd
+  else:
+    toAdd.next = head
+    toAdd.prev = head.prev # copy pointer to last element
+    head.prev = toAdd
+    head = toAdd
+
+proc prepend*[T](head: var PDoublyLinkedNode[T], x: T) {.inline.} = 
+  ## creates a new node with the value `x` and prepends that node to `head`.
+  ## Efficiency: O(1).
+  preprend(head, newDoublyLinkedNode(x))
+
+proc append*[T](head: var PDoublyLinkedNode[T], 
+                toAdd: PDoublyLinkedNode[T]) {.inline.} = 
+  ## appends a node to `head`. Efficiency: O(1).
+  if head == nil:
+    head = toAdd
+    # head.prev stores the last node:
+    head.prev = toAdd
+  else:
+    var last = head.prev
+    assert last.next == nil
+    last.next = toAdd
+    toAdd.prev = last
+    head.prev = toAdd # new last element
+
+proc append*[T](head: var PDoublyLinkedNode[T], x: T) {.inline.} = 
+  ## creates a new node with the value `x` and appends that node to `head`.
+  ## Efficiency: O(1).
+  append(head, newDoublyLinkedNode(x))
+
+
+
+