531 lines
16 KiB
Zig
531 lines
16 KiB
Zig
const std = @import("std.zig");
|
|
const debug = std.debug;
|
|
const assert = debug.assert;
|
|
const testing = std.testing;
|
|
const mem = std.mem;
|
|
const Allocator = mem.Allocator;
|
|
|
|
/// A singly-linked list is headed by a single forward pointer. The elements
|
|
/// are singly linked for minimum space and pointer manipulation overhead at
|
|
/// the expense of O(n) removal for arbitrary elements. New elements can be
|
|
/// added to the list after an existing element or at the head of the list.
|
|
/// A singly-linked list may only be traversed in the forward direction.
|
|
/// Singly-linked lists are ideal for applications with large datasets and
|
|
/// few or no removals or for implementing a LIFO queue.
|
|
pub fn SinglyLinkedList(comptime T: type) type {
|
|
return struct {
|
|
const Self = @This();
|
|
|
|
/// Node inside the linked list wrapping the actual data.
|
|
pub const Node = struct {
|
|
next: ?*Node,
|
|
data: T,
|
|
|
|
pub fn init(data: T) Node {
|
|
return Node{
|
|
.next = null,
|
|
.data = data,
|
|
};
|
|
}
|
|
|
|
/// Insert a new node after the current one.
|
|
///
|
|
/// Arguments:
|
|
/// new_node: Pointer to the new node to insert.
|
|
pub fn insertAfter(node: *Node, new_node: *Node) void {
|
|
new_node.next = node.next;
|
|
node.next = new_node;
|
|
}
|
|
|
|
/// Remove a node from the list.
|
|
///
|
|
/// Arguments:
|
|
/// node: Pointer to the node to be removed.
|
|
/// Returns:
|
|
/// node removed
|
|
pub fn removeNext(node: *Node) ?*Node {
|
|
const next_node = node.next orelse return null;
|
|
node.next = next_node.next;
|
|
return next_node;
|
|
}
|
|
};
|
|
|
|
first: ?*Node,
|
|
|
|
/// Initialize a linked list.
|
|
///
|
|
/// Returns:
|
|
/// An empty linked list.
|
|
pub fn init() Self {
|
|
return Self{
|
|
.first = null,
|
|
};
|
|
}
|
|
|
|
/// Insert a new node after an existing one.
|
|
///
|
|
/// Arguments:
|
|
/// node: Pointer to a node in the list.
|
|
/// new_node: Pointer to the new node to insert.
|
|
pub fn insertAfter(list: *Self, node: *Node, new_node: *Node) void {
|
|
node.insertAfter(new_node);
|
|
}
|
|
|
|
/// Insert a new node at the head.
|
|
///
|
|
/// Arguments:
|
|
/// new_node: Pointer to the new node to insert.
|
|
pub fn prepend(list: *Self, new_node: *Node) void {
|
|
new_node.next = list.first;
|
|
list.first = new_node;
|
|
}
|
|
|
|
/// Remove a node from the list.
|
|
///
|
|
/// Arguments:
|
|
/// node: Pointer to the node to be removed.
|
|
pub fn remove(list: *Self, node: *Node) void {
|
|
if (list.first == node) {
|
|
list.first = node.next;
|
|
} else {
|
|
var current_elm = list.first.?;
|
|
while (current_elm.next != node) {
|
|
current_elm = current_elm.next.?;
|
|
}
|
|
current_elm.next = node.next;
|
|
}
|
|
}
|
|
|
|
/// Remove and return the first node in the list.
|
|
///
|
|
/// Returns:
|
|
/// A pointer to the first node in the list.
|
|
pub fn popFirst(list: *Self) ?*Node {
|
|
const first = list.first orelse return null;
|
|
list.first = first.next;
|
|
return first;
|
|
}
|
|
|
|
/// Allocate a new node.
|
|
///
|
|
/// Arguments:
|
|
/// allocator: Dynamic memory allocator.
|
|
///
|
|
/// Returns:
|
|
/// A pointer to the new node.
|
|
pub fn allocateNode(list: *Self, allocator: *Allocator) !*Node {
|
|
return allocator.create(Node);
|
|
}
|
|
|
|
/// Deallocate a node.
|
|
///
|
|
/// Arguments:
|
|
/// node: Pointer to the node to deallocate.
|
|
/// allocator: Dynamic memory allocator.
|
|
pub fn destroyNode(list: *Self, node: *Node, allocator: *Allocator) void {
|
|
allocator.destroy(node);
|
|
}
|
|
|
|
/// Allocate and initialize a node and its data.
|
|
///
|
|
/// Arguments:
|
|
/// data: The data to put inside the node.
|
|
/// allocator: Dynamic memory allocator.
|
|
///
|
|
/// Returns:
|
|
/// A pointer to the new node.
|
|
pub fn createNode(list: *Self, data: T, allocator: *Allocator) !*Node {
|
|
var node = try list.allocateNode(allocator);
|
|
node.* = Node.init(data);
|
|
return node;
|
|
}
|
|
};
|
|
}
|
|
|
|
test "basic SinglyLinkedList test" {
|
|
const allocator = debug.global_allocator;
|
|
var list = SinglyLinkedList(u32).init();
|
|
|
|
var one = try list.createNode(1, allocator);
|
|
var two = try list.createNode(2, allocator);
|
|
var three = try list.createNode(3, allocator);
|
|
var four = try list.createNode(4, allocator);
|
|
var five = try list.createNode(5, allocator);
|
|
defer {
|
|
list.destroyNode(one, allocator);
|
|
list.destroyNode(two, allocator);
|
|
list.destroyNode(three, allocator);
|
|
list.destroyNode(four, allocator);
|
|
list.destroyNode(five, allocator);
|
|
}
|
|
|
|
list.prepend(two); // {2}
|
|
list.insertAfter(two, five); // {2, 5}
|
|
list.prepend(one); // {1, 2, 5}
|
|
list.insertAfter(two, three); // {1, 2, 3, 5}
|
|
list.insertAfter(three, four); // {1, 2, 3, 4, 5}
|
|
|
|
// Traverse forwards.
|
|
{
|
|
var it = list.first;
|
|
var index: u32 = 1;
|
|
while (it) |node| : (it = node.next) {
|
|
testing.expect(node.data == index);
|
|
index += 1;
|
|
}
|
|
}
|
|
|
|
_ = list.popFirst(); // {2, 3, 4, 5}
|
|
_ = list.remove(five); // {2, 3, 4}
|
|
_ = two.removeNext(); // {2, 4}
|
|
|
|
testing.expect(list.first.?.data == 2);
|
|
testing.expect(list.first.?.next.?.data == 4);
|
|
testing.expect(list.first.?.next.?.next == null);
|
|
}
|
|
|
|
/// A tail queue is headed by a pair of pointers, one to the head of the
|
|
/// list and the other to the tail of the list. The elements are doubly
|
|
/// linked so that an arbitrary element can be removed without a need to
|
|
/// traverse the list. New elements can be added to the list before or
|
|
/// after an existing element, at the head of the list, or at the end of
|
|
/// the list. A tail queue may be traversed in either direction.
|
|
pub fn TailQueue(comptime T: type) type {
|
|
return struct {
|
|
const Self = @This();
|
|
|
|
/// Node inside the linked list wrapping the actual data.
|
|
pub const Node = struct {
|
|
prev: ?*Node,
|
|
next: ?*Node,
|
|
data: T,
|
|
|
|
pub fn init(data: T) Node {
|
|
return Node{
|
|
.prev = null,
|
|
.next = null,
|
|
.data = data,
|
|
};
|
|
}
|
|
};
|
|
|
|
first: ?*Node,
|
|
last: ?*Node,
|
|
len: usize,
|
|
|
|
/// Initialize a linked list.
|
|
///
|
|
/// Returns:
|
|
/// An empty linked list.
|
|
pub fn init() Self {
|
|
return Self{
|
|
.first = null,
|
|
.last = null,
|
|
.len = 0,
|
|
};
|
|
}
|
|
|
|
/// Insert a new node after an existing one.
|
|
///
|
|
/// Arguments:
|
|
/// node: Pointer to a node in the list.
|
|
/// new_node: Pointer to the new node to insert.
|
|
pub fn insertAfter(list: *Self, node: *Node, new_node: *Node) void {
|
|
new_node.prev = node;
|
|
if (node.next) |next_node| {
|
|
// Intermediate node.
|
|
new_node.next = next_node;
|
|
next_node.prev = new_node;
|
|
} else {
|
|
// Last element of the list.
|
|
new_node.next = null;
|
|
list.last = new_node;
|
|
}
|
|
node.next = new_node;
|
|
|
|
list.len += 1;
|
|
}
|
|
|
|
/// Insert a new node before an existing one.
|
|
///
|
|
/// Arguments:
|
|
/// node: Pointer to a node in the list.
|
|
/// new_node: Pointer to the new node to insert.
|
|
pub fn insertBefore(list: *Self, node: *Node, new_node: *Node) void {
|
|
new_node.next = node;
|
|
if (node.prev) |prev_node| {
|
|
// Intermediate node.
|
|
new_node.prev = prev_node;
|
|
prev_node.next = new_node;
|
|
} else {
|
|
// First element of the list.
|
|
new_node.prev = null;
|
|
list.first = new_node;
|
|
}
|
|
node.prev = new_node;
|
|
|
|
list.len += 1;
|
|
}
|
|
|
|
/// Concatenate list2 onto the end of list1, removing all entries from the former.
|
|
///
|
|
/// Arguments:
|
|
/// list1: the list to concatenate onto
|
|
/// list2: the list to be concatenated
|
|
pub fn concatByMoving(list1: *Self, list2: *Self) void {
|
|
const l2_first = list2.first orelse return;
|
|
if (list1.last) |l1_last| {
|
|
l1_last.next = list2.first;
|
|
l2_first.prev = list1.last;
|
|
list1.len += list2.len;
|
|
} else {
|
|
// list1 was empty
|
|
list1.first = list2.first;
|
|
list1.len = list2.len;
|
|
}
|
|
list1.last = list2.last;
|
|
list2.first = null;
|
|
list2.last = null;
|
|
list2.len = 0;
|
|
}
|
|
|
|
/// Insert a new node at the end of the list.
|
|
///
|
|
/// Arguments:
|
|
/// new_node: Pointer to the new node to insert.
|
|
pub fn append(list: *Self, new_node: *Node) void {
|
|
if (list.last) |last| {
|
|
// Insert after last.
|
|
list.insertAfter(last, new_node);
|
|
} else {
|
|
// Empty list.
|
|
list.prepend(new_node);
|
|
}
|
|
}
|
|
|
|
/// Insert a new node at the beginning of the list.
|
|
///
|
|
/// Arguments:
|
|
/// new_node: Pointer to the new node to insert.
|
|
pub fn prepend(list: *Self, new_node: *Node) void {
|
|
if (list.first) |first| {
|
|
// Insert before first.
|
|
list.insertBefore(first, new_node);
|
|
} else {
|
|
// Empty list.
|
|
list.first = new_node;
|
|
list.last = new_node;
|
|
new_node.prev = null;
|
|
new_node.next = null;
|
|
|
|
list.len = 1;
|
|
}
|
|
}
|
|
|
|
/// Remove a node from the list.
|
|
///
|
|
/// Arguments:
|
|
/// node: Pointer to the node to be removed.
|
|
pub fn remove(list: *Self, node: *Node) void {
|
|
if (node.prev) |prev_node| {
|
|
// Intermediate node.
|
|
prev_node.next = node.next;
|
|
} else {
|
|
// First element of the list.
|
|
list.first = node.next;
|
|
}
|
|
|
|
if (node.next) |next_node| {
|
|
// Intermediate node.
|
|
next_node.prev = node.prev;
|
|
} else {
|
|
// Last element of the list.
|
|
list.last = node.prev;
|
|
}
|
|
|
|
list.len -= 1;
|
|
assert(list.len == 0 or (list.first != null and list.last != null));
|
|
}
|
|
|
|
/// Remove and return the last node in the list.
|
|
///
|
|
/// Returns:
|
|
/// A pointer to the last node in the list.
|
|
pub fn pop(list: *Self) ?*Node {
|
|
const last = list.last orelse return null;
|
|
list.remove(last);
|
|
return last;
|
|
}
|
|
|
|
/// Remove and return the first node in the list.
|
|
///
|
|
/// Returns:
|
|
/// A pointer to the first node in the list.
|
|
pub fn popFirst(list: *Self) ?*Node {
|
|
const first = list.first orelse return null;
|
|
list.remove(first);
|
|
return first;
|
|
}
|
|
|
|
/// Allocate a new node.
|
|
///
|
|
/// Arguments:
|
|
/// allocator: Dynamic memory allocator.
|
|
///
|
|
/// Returns:
|
|
/// A pointer to the new node.
|
|
pub fn allocateNode(list: *Self, allocator: *Allocator) !*Node {
|
|
return allocator.create(Node);
|
|
}
|
|
|
|
/// Deallocate a node.
|
|
///
|
|
/// Arguments:
|
|
/// node: Pointer to the node to deallocate.
|
|
/// allocator: Dynamic memory allocator.
|
|
pub fn destroyNode(list: *Self, node: *Node, allocator: *Allocator) void {
|
|
allocator.destroy(node);
|
|
}
|
|
|
|
/// Allocate and initialize a node and its data.
|
|
///
|
|
/// Arguments:
|
|
/// data: The data to put inside the node.
|
|
/// allocator: Dynamic memory allocator.
|
|
///
|
|
/// Returns:
|
|
/// A pointer to the new node.
|
|
pub fn createNode(list: *Self, data: T, allocator: *Allocator) !*Node {
|
|
var node = try list.allocateNode(allocator);
|
|
node.* = Node.init(data);
|
|
return node;
|
|
}
|
|
};
|
|
}
|
|
|
|
test "basic TailQueue test" {
|
|
const allocator = debug.global_allocator;
|
|
var list = TailQueue(u32).init();
|
|
|
|
var one = try list.createNode(1, allocator);
|
|
var two = try list.createNode(2, allocator);
|
|
var three = try list.createNode(3, allocator);
|
|
var four = try list.createNode(4, allocator);
|
|
var five = try list.createNode(5, allocator);
|
|
defer {
|
|
list.destroyNode(one, allocator);
|
|
list.destroyNode(two, allocator);
|
|
list.destroyNode(three, allocator);
|
|
list.destroyNode(four, allocator);
|
|
list.destroyNode(five, allocator);
|
|
}
|
|
|
|
list.append(two); // {2}
|
|
list.append(five); // {2, 5}
|
|
list.prepend(one); // {1, 2, 5}
|
|
list.insertBefore(five, four); // {1, 2, 4, 5}
|
|
list.insertAfter(two, three); // {1, 2, 3, 4, 5}
|
|
|
|
// Traverse forwards.
|
|
{
|
|
var it = list.first;
|
|
var index: u32 = 1;
|
|
while (it) |node| : (it = node.next) {
|
|
testing.expect(node.data == index);
|
|
index += 1;
|
|
}
|
|
}
|
|
|
|
// Traverse backwards.
|
|
{
|
|
var it = list.last;
|
|
var index: u32 = 1;
|
|
while (it) |node| : (it = node.prev) {
|
|
testing.expect(node.data == (6 - index));
|
|
index += 1;
|
|
}
|
|
}
|
|
|
|
var first = list.popFirst(); // {2, 3, 4, 5}
|
|
var last = list.pop(); // {2, 3, 4}
|
|
list.remove(three); // {2, 4}
|
|
|
|
testing.expect(list.first.?.data == 2);
|
|
testing.expect(list.last.?.data == 4);
|
|
testing.expect(list.len == 2);
|
|
}
|
|
|
|
test "TailQueue concatenation" {
|
|
const allocator = debug.global_allocator;
|
|
var list1 = TailQueue(u32).init();
|
|
var list2 = TailQueue(u32).init();
|
|
|
|
var one = try list1.createNode(1, allocator);
|
|
defer list1.destroyNode(one, allocator);
|
|
var two = try list1.createNode(2, allocator);
|
|
defer list1.destroyNode(two, allocator);
|
|
var three = try list1.createNode(3, allocator);
|
|
defer list1.destroyNode(three, allocator);
|
|
var four = try list1.createNode(4, allocator);
|
|
defer list1.destroyNode(four, allocator);
|
|
var five = try list1.createNode(5, allocator);
|
|
defer list1.destroyNode(five, allocator);
|
|
|
|
list1.append(one);
|
|
list1.append(two);
|
|
list2.append(three);
|
|
list2.append(four);
|
|
list2.append(five);
|
|
|
|
list1.concatByMoving(&list2);
|
|
|
|
testing.expect(list1.last == five);
|
|
testing.expect(list1.len == 5);
|
|
testing.expect(list2.first == null);
|
|
testing.expect(list2.last == null);
|
|
testing.expect(list2.len == 0);
|
|
|
|
// Traverse forwards.
|
|
{
|
|
var it = list1.first;
|
|
var index: u32 = 1;
|
|
while (it) |node| : (it = node.next) {
|
|
testing.expect(node.data == index);
|
|
index += 1;
|
|
}
|
|
}
|
|
|
|
// Traverse backwards.
|
|
{
|
|
var it = list1.last;
|
|
var index: u32 = 1;
|
|
while (it) |node| : (it = node.prev) {
|
|
testing.expect(node.data == (6 - index));
|
|
index += 1;
|
|
}
|
|
}
|
|
|
|
// Swap them back, this verifies that concating to an empty list works.
|
|
list2.concatByMoving(&list1);
|
|
|
|
// Traverse forwards.
|
|
{
|
|
var it = list2.first;
|
|
var index: u32 = 1;
|
|
while (it) |node| : (it = node.next) {
|
|
testing.expect(node.data == index);
|
|
index += 1;
|
|
}
|
|
}
|
|
|
|
// Traverse backwards.
|
|
{
|
|
var it = list2.last;
|
|
var index: u32 = 1;
|
|
while (it) |node| : (it = node.prev) {
|
|
testing.expect(node.data == (6 - index));
|
|
index += 1;
|
|
}
|
|
}
|
|
}
|