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#
#
# Nim's Runtime Library
# (c) Copyright 2012 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.
when not defined(nimhygiene):
{.pragma: dirty.}
type
DoublyLinkedNodeObj*[T] = object ## a node a doubly linked list consists of
next*, prev*: ref DoublyLinkedNodeObj[T]
value*: T
DoublyLinkedNode*[T] = ref DoublyLinkedNodeObj[T]
SinglyLinkedNodeObj*[T] = object ## a node a singly linked list consists of
next*: ref SinglyLinkedNodeObj[T]
value*: T
SinglyLinkedNode*[T] = ref SinglyLinkedNodeObj[T]
SinglyLinkedList*[T] = object ## a singly linked list
head*, tail*: SinglyLinkedNode[T]
DoublyLinkedList*[T] = object ## a doubly linked list
head*, tail*: DoublyLinkedNode[T]
SinglyLinkedRing*[T] = object ## a singly linked ring
head*, tail*: SinglyLinkedNode[T]
DoublyLinkedRing*[T] = object ## a doubly linked ring
head*: DoublyLinkedNode[T]
{.deprecated: [TDoublyLinkedNode: DoublyLinkedNodeObj,
PDoublyLinkedNode: DoublyLinkedNode,
TSinglyLinkedNode: SinglyLinkedNodeObj,
PSinglyLinkedNode: SinglyLinkedNode,
TDoublyLinkedList: DoublyLinkedList,
TSinglyLinkedRing: SinglyLinkedRing,
TDoublyLinkedRing: DoublyLinkedRing,
TSinglyLinkedList: SinglyLinkedList].}
proc initSinglyLinkedList*[T](): SinglyLinkedList[T] =
## creates a new singly linked list that is empty.
discard
proc initDoublyLinkedList*[T](): DoublyLinkedList[T] =
## creates a new doubly linked list that is empty.
discard
proc initSinglyLinkedRing*[T](): SinglyLinkedRing[T] =
## creates a new singly linked ring that is empty.
discard
proc initDoublyLinkedRing*[T](): DoublyLinkedRing[T] =
## creates a new doubly linked ring that is empty.
discard
proc newDoublyLinkedNode*[T](value: T): DoublyLinkedNode[T] =
## creates a new doubly linked node with the given `value`.
new(result)
result.value = value
proc newSinglyLinkedNode*[T](value: T): SinglyLinkedNode[T] =
## creates a new singly linked node with the given `value`.
new(result)
result.value = value
template itemsListImpl() {.dirty.} =
var it = L.head
while it != nil:
yield it.value
it = it.next
template itemsRingImpl() {.dirty.} =
var it = L.head
if it != nil:
while true:
yield it.value
it = it.next
if it == L.head: break
template nodesListImpl() {.dirty.} =
var it = L.head
while it != nil:
var nxt = it.next
yield it
it = nxt
template nodesRingImpl() {.dirty.} =
var it = L.head
if it != nil:
while true:
var nxt = it.next
yield it
it = nxt
if it == L.head: break
template findImpl() {.dirty.} =
for x in nodes(L):
if x.value == value: return x
iterator items*[T](L: DoublyLinkedList[T]): T =
## yields every value of `L`.
itemsListImpl()
iterator items*[T](L: SinglyLinkedList[T]): T =
## yields every value of `L`.
itemsListImpl()
iterator items*[T](L: SinglyLinkedRing[T]): T =
## yields every value of `L`.
itemsRingImpl()
iterator items*[T](L: DoublyLinkedRing[T]): T =
## yields every value of `L`.
itemsRingImpl()
iterator mitems*[T](L: var DoublyLinkedList[T]): var T =
## yields every value of `L` so that you can modify it.
itemsListImpl()
iterator mitems*[T](L: var SinglyLinkedList[T]): var T =
## yields every value of `L` so that you can modify it.
itemsListImpl()
iterator mitems*[T](L: var SinglyLinkedRing[T]): var T =
## yields every value of `L` so that you can modify it.
itemsRingImpl()
iterator mitems*[T](L: var DoublyLinkedRing[T]): var T =
## yields every value of `L` so that you can modify it.
itemsRingImpl()
iterator nodes*[T](L: SinglyLinkedList[T]): SinglyLinkedNode[T] =
## iterates over every node of `x`. Removing the current node from the
## list during traversal is supported.
nodesListImpl()
iterator nodes*[T](L: DoublyLinkedList[T]): DoublyLinkedNode[T] =
## iterates over every node of `x`. Removing the current node from the
## list during traversal is supported.
nodesListImpl()
iterator nodes*[T](L: SinglyLinkedRing[T]): SinglyLinkedNode[T] =
## iterates over every node of `x`. Removing the current node from the
## list during traversal is supported.
nodesRingImpl()
iterator nodes*[T](L: DoublyLinkedRing[T]): DoublyLinkedNode[T] =
## iterates over every node of `x`. Removing the current node from the
## list during traversal is supported.
nodesRingImpl()
template dollarImpl() {.dirty.} =
result = "["
for x in nodes(L):
if result.len > 1: result.add(", ")
result.add($x.value)
result.add("]")
proc `$`*[T](L: SinglyLinkedList[T]): string =
## turns a list into its string representation.
dollarImpl()
proc `$`*[T](L: DoublyLinkedList[T]): string =
## turns a list into its string representation.
dollarImpl()
proc `$`*[T](L: SinglyLinkedRing[T]): string =
## turns a list into its string representation.
dollarImpl()
proc `$`*[T](L: DoublyLinkedRing[T]): string =
## turns a list into its string representation.
dollarImpl()
proc find*[T](L: SinglyLinkedList[T], value: T): SinglyLinkedNode[T] =
## searches in the list for a value. Returns nil if the value does not
## exist.
findImpl()
proc find*[T](L: DoublyLinkedList[T], value: T): DoublyLinkedNode[T] =
## searches in the list for a value. Returns nil if the value does not
## exist.
findImpl()
proc find*[T](L: SinglyLinkedRing[T], value: T): SinglyLinkedNode[T] =
## searches in the list for a value. Returns nil if the value does not
## exist.
findImpl()
proc find*[T](L: DoublyLinkedRing[T], value: T): DoublyLinkedNode[T] =
## searches in the list for a value. Returns nil if the value does not
## exist.
findImpl()
proc contains*[T](L: SinglyLinkedList[T], value: T): bool {.inline.} =
## searches in the list for a value. Returns false if the value does not
## exist, true otherwise.
result = find(L, value) != nil
proc contains*[T](L: DoublyLinkedList[T], value: T): bool {.inline.} =
## searches in the list for a value. Returns false if the value does not
## exist, true otherwise.
result = find(L, value) != nil
proc contains*[T](L: SinglyLinkedRing[T], value: T): bool {.inline.} =
## searches in the list for a value. Returns false if the value does not
## exist, true otherwise.
result = find(L, value) != nil
proc contains*[T](L: DoublyLinkedRing[T], value: T): bool {.inline.} =
## searches in the list for a value. Returns false if the value does not
## exist, true otherwise.
result = find(L, value) != nil
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
proc prepend*[T](L: var SinglyLinkedList[T], value: T) {.inline.} =
## prepends a node to `L`. Efficiency: O(1).
prepend(L, newSinglyLinkedNode(value))
proc append*[T](L: var DoublyLinkedList[T], n: DoublyLinkedNode[T]) =
## appends a node `n` to `L`. Efficiency: O(1).
n.next = nil
n.prev = L.tail
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 DoublyLinkedList[T], value: T) =
## appends a value to `L`. Efficiency: O(1).
append(L, newDoublyLinkedNode(value))
proc prepend*[T](L: var DoublyLinkedList[T], n: DoublyLinkedNode[T]) =
## prepends a node `n` to `L`. Efficiency: O(1).
n.prev = nil
n.next = L.head
if L.head != nil:
assert(L.head.prev == nil)
L.head.prev = n
L.head = n
if L.tail == nil: L.tail = n
proc prepend*[T](L: var DoublyLinkedList[T], value: T) =
## prepends a value to `L`. Efficiency: O(1).
prepend(L, newDoublyLinkedNode(value))
proc remove*[T](L: var DoublyLinkedList[T], n: DoublyLinkedNode[T]) =
## removes `n` from `L`. Efficiency: O(1).
if n == L.tail: L.tail = n.prev
if n == L.head: L.head = n.next
if n.next != nil: n.next.prev = n.prev
if n.prev != nil: n.prev.next = n.next
proc append*[T](L: var SinglyLinkedRing[T], n: SinglyLinkedNode[T]) =
## appends a node `n` to `L`. Efficiency: O(1).
if L.head != nil:
n.next = L.head
assert(L.tail != nil)
L.tail.next = n
L.tail = n
else:
n.next = n
L.head = n
L.tail = n
proc append*[T](L: var SinglyLinkedRing[T], value: T) =
## appends a value to `L`. Efficiency: O(1).
append(L, newSinglyLinkedNode(value))
proc prepend*[T](L: var SinglyLinkedRing[T], n: SinglyLinkedNode[T]) =
## prepends a node `n` to `L`. Efficiency: O(1).
if L.head != nil:
n.next = L.head
assert(L.tail != nil)
L.tail.next = n
else:
n.next = n
L.tail = n
L.head = n
proc prepend*[T](L: var SinglyLinkedRing[T], value: T) =
## prepends a value to `L`. Efficiency: O(1).
prepend(L, newSinglyLinkedNode(value))
proc append*[T](L: var DoublyLinkedRing[T], n: DoublyLinkedNode[T]) =
## appends a node `n` to `L`. Efficiency: O(1).
if L.head != nil:
n.next = L.head
n.prev = L.head.prev
L.head.prev.next = n
L.head.prev = n
else:
n.prev = n
n.next = n
L.head = n
proc append*[T](L: var DoublyLinkedRing[T], value: T) =
## appends a value to `L`. Efficiency: O(1).
append(L, newDoublyLinkedNode(value))
proc prepend*[T](L: var DoublyLinkedRing[T], n: DoublyLinkedNode[T]) =
## prepends a node `n` to `L`. Efficiency: O(1).
if L.head != nil:
n.next = L.head
n.prev = L.head.prev
L.head.prev.next = n
L.head.prev = n
else:
n.prev = n
n.next = n
L.head = n
proc prepend*[T](L: var DoublyLinkedRing[T], value: T) =
## prepends a value to `L`. Efficiency: O(1).
prepend(L, newDoublyLinkedNode(value))
proc remove*[T](L: var DoublyLinkedRing[T], n: DoublyLinkedNode[T]) =
## removes `n` from `L`. Efficiency: O(1).
n.next.prev = n.prev
n.prev.next = n.next
if n == L.head:
var p = L.head.prev
if p == L.head:
# only one element left:
L.head = nil
else:
L.head = L.head.prev
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