Doubly Linked List in Powershell

linked-list-cli.ps1

param($ArrayIn)

class Node {
	$Value
	[Node]$Next
	[Node]$Previous
	
	Node($value, [Node]$next, [Node]$previous) {
		$this.Value = $value
		$this.Next = $next
		$this.Previous = $previous
	}
	
	[Node]Traverse([int]$offset) {
		$ListPointer = $this
		
		if ($offset -eq -1) {
			# Traverse to end
			while($ListPointer.Next -ne $null) {
				$ListPointer = $ListPointer.Next
			}
			
			return $ListPointer
		} elseif ($offset -lt 0) {
			return $null
		} elseif ($offset -eq 0) {
			return $this
		}
		
		for ($i = 0; $i -lt $offset; $i++) {
			if ($ListPointer.Next -ne $null) {
				$ListPointer = $ListPointer.Next
			} else {
				break
			}
		}
		
		return $ListPointer
	}
	
	[Node]TraverseBackwards([int]$offset) {
		$ListPointer = $this
		
		if ($offset -eq -1) {
			# Traverse Backwards to end
			while($ListPointer.Previous -ne $null) {
				$ListPointer = $ListPointer.Previous
			}
			
			return $ListPointer
		} elseif ($offset -lt 0) {
			return $null
		} elseif ($offset -eq 0) {
			return $this
		}
		
		for ($i = 0; $i -lt $offset; $i++) {
			if ($ListPointer.Previous -ne $null) {
				$ListPointer = $ListPointer.Previous
			} else {
				break
			}
		}
		
		return $ListPointer
	}
	
	[Node]Append($value) {
		$NextNode = $this.Next
		$this.Next = [Node]::new($value, $NextNode, $this)
		
		if ($NextNode -ne $null) {
			$NextNode.Previous = $this.Next
		}
		
		return $this.Next
	}
	
	[Node]AppendToEnd($value) {
		return $this.Traverse(-1).Append($value)
	}
	
	[Node]AppendToHead($value) {
		return $this.TraverseBackwards(-1).Append($value)
	}
	
	[Node]Insert([int]$offset, $value) {
		if ($offset -eq 0) {
			$this.Append($value)
		} elseif ($offset -lt 0) {
			return $this.TraverseBackwards(-$offset).Append($value)
		}
		
		return $this.Traverse($offset).Append($value)
	}
	
	DeleteThis() {
		$this.Previous.Next = $this.Next
	}
	
	Delete([int]$offset) {
		if ($offset -eq 0) {
			$this.DeleteThis()
		} elseif ($offset -lt 0) {
			$this.TraverseBackwards(-$offset).DeleteThis()
			return
		}
		
		$this.Traverse($offset).DeleteThis()
	}
}

function Print-List {
	param(
		[Node]$Head
	)
	
	$i = 0
	for ($current = $Head; $current -ne $null; $current = $current.Next) {
		$i++
		Write-Host ("Node {0}: {1}" -f $i, $current.Value)
	}
}

$Head = [Node]::new($ArrayIn[0], $null, $null)

for ($i = 1; $i -lt $ArrayIn.Length; $i++) {
   [void]$Head.AppendToEnd($ArrayIn[$i])
}

Print-List $Head

linked-list.ps1

class Node {
	[int]$Value
	[Node]$Next
	[Node]$Previous
	
	Node([int]$value, [Node]$next, [Node]$previous) {
		$this.Value = $value
		$this.Next = $next
		$this.Previous = $previous
	}
	
	[Node]Traverse([int]$offset) {
		$ListPointer = $this
		
		if ($offset -eq -1) {
			# Traverse to end
			while($ListPointer.Next -ne $null) {
				$ListPointer = $ListPointer.Next
			}
			
			return $ListPointer
		} elseif ($offset -lt 0) {
			return $null
		} elseif ($offset -eq 0) {
			return $this
		}
		
		for ($i = 0; $i -lt $offset; $i++) {
			if ($ListPointer.Next -ne $null) {
				$ListPointer = $ListPointer.Next
			} else {
				break
			}
		}
		
		return $ListPointer
	}
	
	[Node]TraverseBackwards([int]$offset) {
		$ListPointer = $this
		
		if ($offset -eq -1) {
			# Traverse Backwards to end
			while($ListPointer.Previous -ne $null) {
				$ListPointer = $ListPointer.Previous
			}
			
			return $ListPointer
		} elseif ($offset -lt 0) {
			return $null
		} elseif ($offset -eq 0) {
			return $this
		}
		
		for ($i = 0; $i -lt $offset; $i++) {
			if ($ListPointer.Previous -ne $null) {
				$ListPointer = $ListPointer.Previous
			} else {
				break
			}
		}
		
		return $ListPointer
	}
	
	[Node]Append([int]$value) {
		$NextNode = $this.Next
		$this.Next = [Node]::new($value, $NextNode, $this)
		
		if ($NextNode -ne $null) {
			$NextNode.Previous = $this.Next
		}
		
		return $this.Next
	}
	
	[Node]AppendToEnd([int]$value) {
		return $this.Traverse(-1).Append($value)
	}
	
	[Node]AppendToHead([int]$value) {
		return $this.TraverseBackwards(-1).Append($value)
	}
	
	[Node]Insert([int]$offset, [int]$value) {
		if ($offset -eq 0) {
			$this.Append($value)
		} elseif ($offset -lt 0) {
			return $this.TraverseBackwards(-$offset).Append($value)
		}
		
		return $this.Traverse($offset).Append($value)
	}
	
	DeleteThis() {
		$this.Previous.Next = $this.Next
	}
	
	Delete([int]$offset) {
		if ($offset -eq 0) {
			$this.DeleteThis()
		} elseif ($offset -lt 0) {
			$this.TraverseBackwards(-$offset).DeleteThis()
			return
		}
		
		$this.Traverse($offset).DeleteThis()
	}
}

function Print-List {
	param(
		[Node]$Head
	)
	
	$i = 0
	for ($current = $Head; $current -ne $null; $current = $current.Next) {
		$i++
		Write-Host ("Node {0}: {1}" -f $i, $current.Value)
	}
}

$Head = [Node]::new(10, $null, $null)
$n1 = $Head.AppendToEnd(11)
$n2 = $Head.AppendToEnd(12)
[void]$Head.AppendToEnd(15)
$n1.DeleteThis()
[void]$Head.Insert(1,50)
$n2.Delete(2)
[void]$n2.AppendToHead(16)
[void]$n2.AppendToHead(18)
$n2.Delete(-2)

Print-List $Head
$Head.Traverse(2)
$n2.TraverseBackwards(-1)