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mirror of https://github.com/robonen/tools.git synced 2026-03-20 10:54:44 +00:00

feat(core/stdlib): implement LinkedList, PriorityQueue, and Queue data structures

This commit is contained in:
2026-02-15 02:36:41 +07:00
parent 09fe8079c0
commit 7b5da22290
37 changed files with 4532 additions and 14 deletions

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import { describe, expect, it } from 'vitest';
import { BinaryHeap } from '.';
describe('BinaryHeap', () => {
describe('constructor', () => {
it('should create an empty heap', () => {
const heap = new BinaryHeap<number>();
expect(heap.length).toBe(0);
expect(heap.isEmpty).toBe(true);
});
it('should create a heap from single value', () => {
const heap = new BinaryHeap(42);
expect(heap.length).toBe(1);
expect(heap.peek()).toBe(42);
});
it('should create a heap from array (heapify)', () => {
const heap = new BinaryHeap([5, 3, 8, 1, 4]);
expect(heap.length).toBe(5);
expect(heap.peek()).toBe(1);
});
it('should accept a custom comparator for max-heap', () => {
const heap = new BinaryHeap([5, 3, 8, 1, 4], {
comparator: (a, b) => b - a,
});
expect(heap.peek()).toBe(8);
});
});
describe('push', () => {
it('should insert elements maintaining heap property', () => {
const heap = new BinaryHeap<number>();
heap.push(5);
heap.push(3);
heap.push(8);
heap.push(1);
expect(heap.peek()).toBe(1);
expect(heap.length).toBe(4);
});
it('should handle duplicate values', () => {
const heap = new BinaryHeap<number>();
heap.push(3);
heap.push(3);
heap.push(3);
expect(heap.length).toBe(3);
expect(heap.peek()).toBe(3);
});
});
describe('pop', () => {
it('should return undefined for empty heap', () => {
const heap = new BinaryHeap<number>();
expect(heap.pop()).toBeUndefined();
});
it('should extract elements in min-heap order', () => {
const heap = new BinaryHeap([5, 3, 8, 1, 4, 2, 7, 6]);
const sorted: number[] = [];
while (!heap.isEmpty) {
sorted.push(heap.pop()!);
}
expect(sorted).toEqual([1, 2, 3, 4, 5, 6, 7, 8]);
});
it('should extract elements in max-heap order with custom comparator', () => {
const heap = new BinaryHeap([5, 3, 8, 1, 4], {
comparator: (a, b) => b - a,
});
const sorted: number[] = [];
while (!heap.isEmpty) {
sorted.push(heap.pop()!);
}
expect(sorted).toEqual([8, 5, 4, 3, 1]);
});
it('should handle single element', () => {
const heap = new BinaryHeap(42);
expect(heap.pop()).toBe(42);
expect(heap.isEmpty).toBe(true);
});
});
describe('peek', () => {
it('should return undefined for empty heap', () => {
const heap = new BinaryHeap<number>();
expect(heap.peek()).toBeUndefined();
});
it('should return root without removing it', () => {
const heap = new BinaryHeap([5, 3, 1]);
expect(heap.peek()).toBe(1);
expect(heap.length).toBe(3);
});
});
describe('clear', () => {
it('should remove all elements', () => {
const heap = new BinaryHeap([1, 2, 3]);
const result = heap.clear();
expect(heap.length).toBe(0);
expect(heap.isEmpty).toBe(true);
expect(result).toBe(heap);
});
});
describe('toArray', () => {
it('should return empty array for empty heap', () => {
const heap = new BinaryHeap<number>();
expect(heap.toArray()).toEqual([]);
});
it('should return a shallow copy', () => {
const heap = new BinaryHeap([3, 1, 2]);
const arr = heap.toArray();
arr.push(99);
expect(heap.length).toBe(3);
});
});
describe('toString', () => {
it('should return formatted string', () => {
const heap = new BinaryHeap([1, 2, 3]);
expect(heap.toString()).toBe('BinaryHeap(3)');
});
});
describe('iterator', () => {
it('should iterate over heap elements', () => {
const heap = new BinaryHeap([5, 3, 8, 1]);
const elements = [...heap];
expect(elements.length).toBe(4);
expect(elements[0]).toBe(1);
});
});
describe('custom comparator', () => {
it('should work with string length comparator', () => {
const heap = new BinaryHeap(['banana', 'apple', 'kiwi', 'fig'], {
comparator: (a, b) => a.length - b.length,
});
expect(heap.pop()).toBe('fig');
expect(heap.pop()).toBe('kiwi');
});
it('should work with object comparator', () => {
interface Task {
priority: number;
name: string;
}
const heap = new BinaryHeap<Task>(
[
{ priority: 3, name: 'low' },
{ priority: 1, name: 'high' },
{ priority: 2, name: 'medium' },
],
{ comparator: (a, b) => a.priority - b.priority },
);
expect(heap.pop()?.name).toBe('high');
expect(heap.pop()?.name).toBe('medium');
expect(heap.pop()?.name).toBe('low');
});
});
describe('heapify', () => {
it('should correctly heapify large arrays', () => {
const values = Array.from({ length: 1000 }, () => Math.random() * 1000 | 0);
const heap = new BinaryHeap(values);
const sorted: number[] = [];
while (!heap.isEmpty) {
sorted.push(heap.pop()!);
}
const expected = [...values].sort((a, b) => a - b);
expect(sorted).toEqual(expected);
});
});
describe('interleaved operations', () => {
it('should maintain heap property with mixed push and pop', () => {
const heap = new BinaryHeap<number>();
heap.push(10);
heap.push(5);
expect(heap.pop()).toBe(5);
heap.push(3);
heap.push(7);
expect(heap.pop()).toBe(3);
heap.push(1);
expect(heap.pop()).toBe(1);
expect(heap.pop()).toBe(7);
expect(heap.pop()).toBe(10);
expect(heap.pop()).toBeUndefined();
});
});
});

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import { first } from '../../arrays';
import { isArray } from '../../types';
import type { BinaryHeapLike, Comparator } from './types';
export type { BinaryHeapLike, Comparator } from './types';
export interface BinaryHeapOptions<T> {
comparator?: Comparator<T>;
}
/**
* Default min-heap comparator for numeric values
*
* @param {number} a First element
* @param {number} b Second element
* @returns {number} Negative if a < b, positive if a > b, zero if equal
*/
const defaultComparator: Comparator<any> = (a: number, b: number) => a - b;
/**
* @name BinaryHeap
* @category Data Structures
* @description Binary heap backed by a flat array with configurable comparator
*
* @since 0.0.8
*
* @template T The type of elements stored in the heap
*/
export class BinaryHeap<T> implements BinaryHeapLike<T> {
/**
* The comparator function used to order elements
*
* @private
* @type {Comparator<T>}
*/
private readonly comparator: Comparator<T>;
/**
* Internal flat array backing the heap
*
* @private
* @type {T[]}
*/
private readonly heap: T[] = [];
/**
* Creates an instance of BinaryHeap
*
* @param {(T[] | T)} [initialValues] The initial values to heapify
* @param {BinaryHeapOptions<T>} [options] Heap configuration
*/
constructor(initialValues?: T[] | T, options?: BinaryHeapOptions<T>) {
this.comparator = options?.comparator ?? defaultComparator;
if (initialValues != null) {
const items = isArray(initialValues) ? initialValues : [initialValues];
this.heap.push(...items);
this.heapify();
}
}
/**
* Gets the number of elements in the heap
* @returns {number} The number of elements in the heap
*/
public get length(): number {
return this.heap.length;
}
/**
* Checks if the heap is empty
* @returns {boolean} `true` if the heap is empty, `false` otherwise
*/
public get isEmpty(): boolean {
return this.heap.length === 0;
}
/**
* Pushes an element into the heap
* @param {T} element The element to insert
*/
public push(element: T): void {
this.heap.push(element);
this.siftUp(this.heap.length - 1);
}
/**
* Removes and returns the root element (min or max depending on comparator)
* @returns {T | undefined} The root element, or `undefined` if the heap is empty
*/
public pop(): T | undefined {
if (this.heap.length === 0) return undefined;
const root = first(this.heap)!;
const last = this.heap.pop()!;
if (this.heap.length > 0) {
this.heap[0] = last;
this.siftDown(0);
}
return root;
}
/**
* Returns the root element without removing it
* @returns {T | undefined} The root element, or `undefined` if the heap is empty
*/
public peek(): T | undefined {
return first(this.heap);
}
/**
* Removes all elements from the heap
* @returns {this} The heap instance for chaining
*/
public clear(): this {
this.heap.length = 0;
return this;
}
/**
* Returns a shallow copy of the heap elements as an array (heap order, not sorted)
* @returns {T[]} Array of elements in heap order
*/
public toArray(): T[] {
return this.heap.slice();
}
/**
* Returns a string representation of the heap
* @returns {string} String representation
*/
public toString(): string {
return `BinaryHeap(${this.heap.length})`;
}
/**
* Iterator over heap elements in heap order
*/
public *[Symbol.iterator](): Iterator<T> {
yield* this.heap;
}
/**
* Async iterator over heap elements in heap order
*/
public async *[Symbol.asyncIterator](): AsyncIterator<T> {
for (const element of this.heap)
yield element;
}
/**
* Restores heap property by sifting an element up
*
* @private
* @param {number} index The index of the element to sift up
*/
private siftUp(index: number): void {
const heap = this.heap;
const cmp = this.comparator;
while (index > 0) {
const parent = (index - 1) >> 1;
if (cmp(heap[index]!, heap[parent]!) >= 0) break;
const temp = heap[index]!;
heap[index] = heap[parent]!;
heap[parent] = temp;
index = parent;
}
}
/**
* Restores heap property by sifting an element down
*
* @private
* @param {number} index The index of the element to sift down
*/
private siftDown(index: number): void {
const heap = this.heap;
const cmp = this.comparator;
const length = heap.length;
while (true) {
let smallest = index;
const left = 2 * index + 1;
const right = 2 * index + 2;
if (left < length && cmp(heap[left]!, heap[smallest]!) < 0) {
smallest = left;
}
if (right < length && cmp(heap[right]!, heap[smallest]!) < 0) {
smallest = right;
}
if (smallest === index) break;
const temp = heap[index]!;
heap[index] = heap[smallest]!;
heap[smallest] = temp;
index = smallest;
}
}
/**
* Builds heap from unordered array in O(n) using Floyd's algorithm
*
* @private
*/
private heapify(): void {
for (let i = (this.heap.length >> 1) - 1; i >= 0; i--) {
this.siftDown(i);
}
}
}

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export type Comparator<T> = (a: T, b: T) => number;
export interface BinaryHeapLike<T> extends Iterable<T>, AsyncIterable<T> {
readonly length: number;
readonly isEmpty: boolean;
push(element: T): void;
pop(): T | undefined;
peek(): T | undefined;
clear(): this;
toArray(): T[];
toString(): string;
}

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import { describe, it, expect } from 'vitest';
import { CircularBuffer } from '.';
describe('circularBuffer', () => {
describe('constructor', () => {
it('create an empty buffer', () => {
const buf = new CircularBuffer<number>();
expect(buf.length).toBe(0);
expect(buf.isEmpty).toBe(true);
expect(buf.capacity).toBeGreaterThanOrEqual(4);
});
it('create a buffer with initial array', () => {
const buf = new CircularBuffer([1, 2, 3]);
expect(buf.length).toBe(3);
expect(buf.peekFront()).toBe(1);
expect(buf.peekBack()).toBe(3);
});
it('create a buffer with a single value', () => {
const buf = new CircularBuffer(42);
expect(buf.length).toBe(1);
expect(buf.peekFront()).toBe(42);
});
it('create a buffer with initial capacity hint', () => {
const buf = new CircularBuffer<number>(undefined, 32);
expect(buf.capacity).toBe(32);
});
it('round capacity up to next power of two', () => {
const buf = new CircularBuffer<number>(undefined, 5);
expect(buf.capacity).toBe(8);
});
});
describe('pushBack / popFront', () => {
it('FIFO order', () => {
const buf = new CircularBuffer<number>();
buf.pushBack(1);
buf.pushBack(2);
buf.pushBack(3);
expect(buf.popFront()).toBe(1);
expect(buf.popFront()).toBe(2);
expect(buf.popFront()).toBe(3);
});
});
describe('pushFront / popBack', () => {
it('LIFO order', () => {
const buf = new CircularBuffer<number>();
buf.pushFront(1);
buf.pushFront(2);
buf.pushFront(3);
expect(buf.popBack()).toBe(1);
expect(buf.popBack()).toBe(2);
expect(buf.popBack()).toBe(3);
});
});
describe('popFront', () => {
it('return undefined if empty', () => {
const buf = new CircularBuffer<number>();
expect(buf.popFront()).toBeUndefined();
});
});
describe('popBack', () => {
it('return undefined if empty', () => {
const buf = new CircularBuffer<number>();
expect(buf.popBack()).toBeUndefined();
});
});
describe('peekFront / peekBack', () => {
it('return elements without removing', () => {
const buf = new CircularBuffer([1, 2, 3]);
expect(buf.peekFront()).toBe(1);
expect(buf.peekBack()).toBe(3);
expect(buf.length).toBe(3);
});
it('return undefined if empty', () => {
const buf = new CircularBuffer<number>();
expect(buf.peekFront()).toBeUndefined();
expect(buf.peekBack()).toBeUndefined();
});
});
describe('get', () => {
it('access element by logical index', () => {
const buf = new CircularBuffer([10, 20, 30]);
expect(buf.get(0)).toBe(10);
expect(buf.get(1)).toBe(20);
expect(buf.get(2)).toBe(30);
});
it('return undefined for out-of-bounds', () => {
const buf = new CircularBuffer([1, 2]);
expect(buf.get(-1)).toBeUndefined();
expect(buf.get(2)).toBeUndefined();
});
it('work correctly after wrap-around', () => {
const buf = new CircularBuffer<number>(undefined, 4);
buf.pushBack(1);
buf.pushBack(2);
buf.pushBack(3);
buf.pushBack(4);
buf.popFront();
buf.popFront();
buf.pushBack(5);
buf.pushBack(6);
expect(buf.get(0)).toBe(3);
expect(buf.get(1)).toBe(4);
expect(buf.get(2)).toBe(5);
expect(buf.get(3)).toBe(6);
});
});
describe('clear', () => {
it('clear the buffer', () => {
const buf = new CircularBuffer([1, 2, 3]);
buf.clear();
expect(buf.length).toBe(0);
expect(buf.isEmpty).toBe(true);
});
it('return this for chaining', () => {
const buf = new CircularBuffer([1]);
expect(buf.clear()).toBe(buf);
});
});
describe('auto-grow', () => {
it('grow when capacity is exceeded', () => {
const buf = new CircularBuffer<number>();
const initialCapacity = buf.capacity;
for (let i = 0; i < initialCapacity + 1; i++)
buf.pushBack(i);
expect(buf.length).toBe(initialCapacity + 1);
expect(buf.capacity).toBe(initialCapacity * 2);
});
it('preserve order after grow', () => {
const buf = new CircularBuffer<number>(undefined, 4);
buf.pushBack(1);
buf.pushBack(2);
buf.popFront();
buf.pushBack(3);
buf.pushBack(4);
buf.pushBack(5);
buf.pushBack(6);
expect(buf.toArray()).toEqual([2, 3, 4, 5, 6]);
});
});
describe('wrap-around', () => {
it('handle wrap-around correctly', () => {
const buf = new CircularBuffer<number>(undefined, 4);
buf.pushBack(1);
buf.pushBack(2);
buf.pushBack(3);
buf.pushBack(4);
buf.popFront();
buf.popFront();
buf.pushBack(5);
buf.pushBack(6);
expect(buf.toArray()).toEqual([3, 4, 5, 6]);
});
it('handle alternating front/back', () => {
const buf = new CircularBuffer<number>();
buf.pushFront(3);
buf.pushBack(4);
buf.pushFront(2);
buf.pushBack(5);
buf.pushFront(1);
expect(buf.toArray()).toEqual([1, 2, 3, 4, 5]);
});
});
describe('toArray', () => {
it('return elements front to back', () => {
const buf = new CircularBuffer([1, 2, 3]);
expect(buf.toArray()).toEqual([1, 2, 3]);
});
it('return empty array if empty', () => {
const buf = new CircularBuffer<number>();
expect(buf.toArray()).toEqual([]);
});
});
describe('toString', () => {
it('return comma-separated string', () => {
const buf = new CircularBuffer([1, 2, 3]);
expect(buf.toString()).toBe('1,2,3');
});
});
describe('iteration', () => {
it('iterate front to back', () => {
const buf = new CircularBuffer([1, 2, 3]);
expect([...buf]).toEqual([1, 2, 3]);
});
it('iterate asynchronously', async () => {
const buf = new CircularBuffer([1, 2, 3]);
const elements: number[] = [];
for await (const element of buf)
elements.push(element);
expect(elements).toEqual([1, 2, 3]);
});
});
});

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import { isArray } from '../../types';
import type { CircularBufferLike } from './types';
export type { CircularBufferLike } from './types';
const MIN_CAPACITY = 4;
/**
* @name CircularBuffer
* @category Data Structures
* @description A circular (ring) buffer with automatic growth, O(1) push/pop on both ends
*
* @since 0.0.8
*
* @template T The type of elements stored in the buffer
*/
export class CircularBuffer<T> implements CircularBufferLike<T> {
/**
* The internal storage
*
* @private
* @type {(T | undefined)[]}
*/
private buffer: (T | undefined)[];
/**
* The index of the front element
*
* @private
* @type {number}
*/
private head: number;
/**
* The number of elements in the buffer
*
* @private
* @type {number}
*/
private count: number;
/**
* Creates an instance of CircularBuffer
*
* @param {(T[] | T)} [initialValues] The initial values to add to the buffer
* @param {number} [initialCapacity] The initial capacity hint (rounded up to next power of two)
*/
constructor(initialValues?: T[] | T, initialCapacity?: number) {
this.head = 0;
this.count = 0;
const items = isArray(initialValues) ? initialValues : initialValues !== undefined ? [initialValues] : [];
const requested = Math.max(items.length, initialCapacity ?? 0);
const cap = Math.max(MIN_CAPACITY, nextPowerOfTwo(requested));
this.buffer = new Array(cap);
for (const item of items)
this.pushBack(item);
}
/**
* Gets the number of elements in the buffer
* @returns {number}
*/
get length() {
return this.count;
}
/**
* Gets the current capacity of the buffer
* @returns {number}
*/
get capacity() {
return this.buffer.length;
}
/**
* Checks if the buffer is empty
* @returns {boolean}
*/
get isEmpty() {
return this.count === 0;
}
/**
* Checks if the buffer is at capacity (before auto-grow)
* @returns {boolean}
*/
get isFull() {
return this.count === this.buffer.length;
}
/**
* Adds an element to the back of the buffer
* @param {T} element The element to add
*/
pushBack(element: T) {
if (this.count === this.buffer.length)
this.grow();
this.buffer[(this.head + this.count) & (this.buffer.length - 1)] = element;
this.count++;
}
/**
* Adds an element to the front of the buffer
* @param {T} element The element to add
*/
pushFront(element: T) {
if (this.count === this.buffer.length)
this.grow();
this.head = (this.head - 1 + this.buffer.length) & (this.buffer.length - 1);
this.buffer[this.head] = element;
this.count++;
}
/**
* Removes and returns the back element
* @returns {T | undefined} The back element, or undefined if empty
*/
popBack() {
if (this.isEmpty)
return undefined;
const index = (this.head + this.count - 1) & (this.buffer.length - 1);
const element = this.buffer[index];
this.buffer[index] = undefined;
this.count--;
return element;
}
/**
* Removes and returns the front element
* @returns {T | undefined} The front element, or undefined if empty
*/
popFront() {
if (this.isEmpty)
return undefined;
const element = this.buffer[this.head];
this.buffer[this.head] = undefined;
this.head = (this.head + 1) & (this.buffer.length - 1);
this.count--;
return element;
}
/**
* Returns the back element without removing it
* @returns {T | undefined}
*/
peekBack() {
if (this.isEmpty)
return undefined;
return this.buffer[(this.head + this.count - 1) & (this.buffer.length - 1)];
}
/**
* Returns the front element without removing it
* @returns {T | undefined}
*/
peekFront() {
if (this.isEmpty)
return undefined;
return this.buffer[this.head];
}
/**
* Gets element at logical index (0 = front)
* @param {number} index The logical index
* @returns {T | undefined}
*/
get(index: number) {
if (index < 0 || index >= this.count)
return undefined;
return this.buffer[(this.head + index) & (this.buffer.length - 1)];
}
/**
* Clears the buffer
*
* @returns {this}
*/
clear() {
this.buffer = new Array(MIN_CAPACITY);
this.head = 0;
this.count = 0;
return this;
}
/**
* Converts the buffer to an array from front to back
*
* @returns {T[]}
*/
toArray() {
const result = new Array<T>(this.count);
for (let i = 0; i < this.count; i++)
result[i] = this.buffer[(this.head + i) & (this.buffer.length - 1)] as T;
return result;
}
/**
* Returns a string representation
*
* @returns {string}
*/
toString() {
return this.toArray().toString();
}
/**
* Returns an iterator (front to back)
*
* @returns {IterableIterator<T>}
*/
[Symbol.iterator]() {
return this.toArray()[Symbol.iterator]();
}
/**
* Returns an async iterator (front to back)
*
* @returns {AsyncIterableIterator<T>}
*/
async *[Symbol.asyncIterator]() {
for (const element of this)
yield element;
}
/**
* Doubles the buffer capacity and linearizes elements
*
* @private
*/
private grow() {
const newCapacity = this.buffer.length << 1;
const newBuffer = new Array<T | undefined>(newCapacity);
for (let i = 0; i < this.count; i++)
newBuffer[i] = this.buffer[(this.head + i) & (this.buffer.length - 1)];
this.buffer = newBuffer;
this.head = 0;
}
}
/**
* Returns the next power of two >= n
*
* @param {number} n
* @returns {number}
*/
function nextPowerOfTwo(n: number): number {
if (n <= 0)
return 1;
n--;
n |= n >> 1;
n |= n >> 2;
n |= n >> 4;
n |= n >> 8;
n |= n >> 16;
return n + 1;
}

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export interface CircularBufferLike<T> extends Iterable<T>, AsyncIterable<T> {
readonly length: number;
readonly capacity: number;
readonly isEmpty: boolean;
readonly isFull: boolean;
pushBack(element: T): void;
pushFront(element: T): void;
popBack(): T | undefined;
popFront(): T | undefined;
peekBack(): T | undefined;
peekFront(): T | undefined;
get(index: number): T | undefined;
clear(): this;
toArray(): T[];
toString(): string;
}

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import { describe, it, expect } from 'vitest';
import { Deque } from '.';
describe('deque', () => {
describe('constructor', () => {
it('create an empty deque if no initial values are provided', () => {
const deque = new Deque<number>();
expect(deque.length).toBe(0);
expect(deque.isEmpty).toBe(true);
});
it('create a deque with the provided initial values', () => {
const deque = new Deque([1, 2, 3]);
expect(deque.length).toBe(3);
expect(deque.peekFront()).toBe(1);
expect(deque.peekBack()).toBe(3);
});
it('create a deque with a single initial value', () => {
const deque = new Deque(42);
expect(deque.length).toBe(1);
expect(deque.peekFront()).toBe(42);
});
it('create a deque with the provided options', () => {
const deque = new Deque<number>(undefined, { maxSize: 5 });
expect(deque.length).toBe(0);
expect(deque.isFull).toBe(false);
});
});
describe('pushBack', () => {
it('add an element to the back', () => {
const deque = new Deque<number>();
deque.pushBack(1).pushBack(2);
expect(deque.peekFront()).toBe(1);
expect(deque.peekBack()).toBe(2);
expect(deque.length).toBe(2);
});
it('throw an error if the deque is full', () => {
const deque = new Deque<number>(undefined, { maxSize: 1 });
deque.pushBack(1);
expect(() => deque.pushBack(2)).toThrow(new RangeError('Deque is full'));
});
it('return this for chaining', () => {
const deque = new Deque<number>();
expect(deque.pushBack(1)).toBe(deque);
});
});
describe('pushFront', () => {
it('add an element to the front', () => {
const deque = new Deque<number>();
deque.pushFront(1).pushFront(2);
expect(deque.peekFront()).toBe(2);
expect(deque.peekBack()).toBe(1);
expect(deque.length).toBe(2);
});
it('throw an error if the deque is full', () => {
const deque = new Deque<number>(undefined, { maxSize: 1 });
deque.pushFront(1);
expect(() => deque.pushFront(2)).toThrow(new RangeError('Deque is full'));
});
it('return this for chaining', () => {
const deque = new Deque<number>();
expect(deque.pushFront(1)).toBe(deque);
});
});
describe('popBack', () => {
it('remove and return the back element', () => {
const deque = new Deque([1, 2, 3]);
expect(deque.popBack()).toBe(3);
expect(deque.length).toBe(2);
});
it('return undefined if the deque is empty', () => {
const deque = new Deque<number>();
expect(deque.popBack()).toBeUndefined();
});
});
describe('popFront', () => {
it('remove and return the front element', () => {
const deque = new Deque([1, 2, 3]);
expect(deque.popFront()).toBe(1);
expect(deque.length).toBe(2);
});
it('return undefined if the deque is empty', () => {
const deque = new Deque<number>();
expect(deque.popFront()).toBeUndefined();
});
});
describe('peekBack', () => {
it('return the back element without removing it', () => {
const deque = new Deque([1, 2, 3]);
expect(deque.peekBack()).toBe(3);
expect(deque.length).toBe(3);
});
it('return undefined if the deque is empty', () => {
const deque = new Deque<number>();
expect(deque.peekBack()).toBeUndefined();
});
});
describe('peekFront', () => {
it('return the front element without removing it', () => {
const deque = new Deque([1, 2, 3]);
expect(deque.peekFront()).toBe(1);
expect(deque.length).toBe(3);
});
it('return undefined if the deque is empty', () => {
const deque = new Deque<number>();
expect(deque.peekFront()).toBeUndefined();
});
});
describe('clear', () => {
it('clear the deque', () => {
const deque = new Deque([1, 2, 3]);
deque.clear();
expect(deque.length).toBe(0);
expect(deque.isEmpty).toBe(true);
});
it('return this for chaining', () => {
const deque = new Deque([1, 2, 3]);
expect(deque.clear()).toBe(deque);
});
});
describe('toArray', () => {
it('return elements from front to back', () => {
const deque = new Deque([1, 2, 3]);
expect(deque.toArray()).toEqual([1, 2, 3]);
});
it('return correct order after mixed operations', () => {
const deque = new Deque<number>();
deque.pushBack(2);
deque.pushBack(3);
deque.pushFront(1);
deque.pushFront(0);
expect(deque.toArray()).toEqual([0, 1, 2, 3]);
});
});
describe('toString', () => {
it('return comma-separated string', () => {
const deque = new Deque([1, 2, 3]);
expect(deque.toString()).toBe('1,2,3');
});
});
describe('iteration', () => {
it('iterate in front-to-back order', () => {
const deque = new Deque([1, 2, 3]);
expect([...deque]).toEqual([1, 2, 3]);
});
it('iterate asynchronously', async () => {
const deque = new Deque([1, 2, 3]);
const elements: number[] = [];
for await (const element of deque)
elements.push(element);
expect(elements).toEqual([1, 2, 3]);
});
});
describe('circular buffer behavior', () => {
it('handle wrap-around correctly', () => {
const deque = new Deque<number>();
for (let i = 0; i < 4; i++)
deque.pushBack(i);
deque.popFront();
deque.popFront();
deque.pushBack(4);
deque.pushBack(5);
expect(deque.toArray()).toEqual([2, 3, 4, 5]);
});
it('grow the buffer when needed', () => {
const deque = new Deque<number>();
for (let i = 0; i < 100; i++)
deque.pushBack(i);
expect(deque.length).toBe(100);
expect(deque.peekFront()).toBe(0);
expect(deque.peekBack()).toBe(99);
});
it('handle alternating front/back operations', () => {
const deque = new Deque<number>();
deque.pushFront(3);
deque.pushBack(4);
deque.pushFront(2);
deque.pushBack(5);
deque.pushFront(1);
expect(deque.toArray()).toEqual([1, 2, 3, 4, 5]);
expect(deque.popFront()).toBe(1);
expect(deque.popBack()).toBe(5);
expect(deque.toArray()).toEqual([2, 3, 4]);
});
});
describe('mixed operations', () => {
it('use as a stack (LIFO)', () => {
const deque = new Deque<number>();
deque.pushBack(1).pushBack(2).pushBack(3);
expect(deque.popBack()).toBe(3);
expect(deque.popBack()).toBe(2);
expect(deque.popBack()).toBe(1);
});
it('use as a queue (FIFO)', () => {
const deque = new Deque<number>();
deque.pushBack(1).pushBack(2).pushBack(3);
expect(deque.popFront()).toBe(1);
expect(deque.popFront()).toBe(2);
expect(deque.popFront()).toBe(3);
});
it('reuse deque after clear', () => {
const deque = new Deque([1, 2, 3]);
deque.clear();
deque.pushBack(4);
expect(deque.length).toBe(1);
expect(deque.peekFront()).toBe(4);
});
it('maxSize limits capacity', () => {
const deque = new Deque<number>(undefined, { maxSize: 3 });
deque.pushBack(1).pushBack(2).pushBack(3);
expect(deque.isFull).toBe(true);
expect(() => deque.pushFront(0)).toThrow(new RangeError('Deque is full'));
deque.popFront();
deque.pushFront(0);
expect(deque.toArray()).toEqual([0, 2, 3]);
});
});
});

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import { CircularBuffer } from '../CircularBuffer';
import type { DequeLike } from './types';
export type { DequeLike } from './types';
export interface DequeOptions {
maxSize?: number;
}
/**
* @name Deque
* @category Data Structures
* @description Represents a double-ended queue backed by a circular buffer
*
* @since 0.0.8
*
* @template T The type of elements stored in the deque
*/
export class Deque<T> implements DequeLike<T> {
/**
* The maximum number of elements that the deque can hold
*
* @private
* @type {number}
*/
private readonly maxSize: number;
/**
* The underlying circular buffer
*
* @private
* @type {CircularBuffer<T>}
*/
private readonly buffer: CircularBuffer<T>;
/**
* Creates an instance of Deque
*
* @param {(T[] | T)} [initialValues] The initial values to add to the deque
* @param {DequeOptions} [options] The options for the deque
*/
constructor(initialValues?: T[] | T, options?: DequeOptions) {
this.maxSize = options?.maxSize ?? Infinity;
this.buffer = new CircularBuffer(initialValues);
}
/**
* Gets the number of elements in the deque
* @returns {number} The number of elements in the deque
*/
get length() {
return this.buffer.length;
}
/**
* Checks if the deque is empty
* @returns {boolean} `true` if the deque is empty, `false` otherwise
*/
get isEmpty() {
return this.buffer.isEmpty;
}
/**
* Checks if the deque is full
* @returns {boolean} `true` if the deque is full, `false` otherwise
*/
get isFull() {
return this.buffer.length === this.maxSize;
}
/**
* Adds an element to the back of the deque
* @param {T} element The element to add
* @returns {this}
* @throws {RangeError} If the deque is full
*/
pushBack(element: T) {
if (this.isFull)
throw new RangeError('Deque is full');
this.buffer.pushBack(element);
return this;
}
/**
* Adds an element to the front of the deque
* @param {T} element The element to add
* @returns {this}
* @throws {RangeError} If the deque is full
*/
pushFront(element: T) {
if (this.isFull)
throw new RangeError('Deque is full');
this.buffer.pushFront(element);
return this;
}
/**
* Removes and returns the back element of the deque
* @returns {T | undefined} The back element, or undefined if empty
*/
popBack() {
return this.buffer.popBack();
}
/**
* Removes and returns the front element of the deque
* @returns {T | undefined} The front element, or undefined if empty
*/
popFront() {
return this.buffer.popFront();
}
/**
* Returns the back element without removing it
* @returns {T | undefined} The back element, or undefined if empty
*/
peekBack() {
return this.buffer.peekBack();
}
/**
* Returns the front element without removing it
* @returns {T | undefined} The front element, or undefined if empty
*/
peekFront() {
return this.buffer.peekFront();
}
/**
* Clears the deque
*
* @returns {this}
*/
clear() {
this.buffer.clear();
return this;
}
/**
* Converts the deque to an array from front to back
*
* @returns {T[]}
*/
toArray() {
return this.buffer.toArray();
}
/**
* Returns a string representation of the deque
*
* @returns {string}
*/
toString() {
return this.buffer.toString();
}
/**
* Returns an iterator for the deque (front to back)
*
* @returns {IterableIterator<T>}
*/
[Symbol.iterator]() {
return this.buffer[Symbol.iterator]();
}
/**
* Returns an async iterator for the deque (front to back)
*
* @returns {AsyncIterableIterator<T>}
*/
async *[Symbol.asyncIterator]() {
for (const element of this.buffer)
yield element;
}
}

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export interface DequeLike<T> extends Iterable<T>, AsyncIterable<T> {
readonly length: number;
readonly isEmpty: boolean;
readonly isFull: boolean;
pushBack(element: T): this;
pushFront(element: T): this;
popBack(): T | undefined;
popFront(): T | undefined;
peekBack(): T | undefined;
peekFront(): T | undefined;
clear(): this;
toArray(): T[];
toString(): string;
}

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import { describe, expect, it } from 'vitest';
import { LinkedList } from '.';
describe('LinkedList', () => {
describe('constructor', () => {
it('should create an empty list', () => {
const list = new LinkedList<number>();
expect(list.length).toBe(0);
expect(list.isEmpty).toBe(true);
expect(list.head).toBeUndefined();
expect(list.tail).toBeUndefined();
});
it('should create a list from single value', () => {
const list = new LinkedList(42);
expect(list.length).toBe(1);
expect(list.peekFront()).toBe(42);
expect(list.peekBack()).toBe(42);
});
it('should create a list from array', () => {
const list = new LinkedList([1, 2, 3]);
expect(list.length).toBe(3);
expect(list.peekFront()).toBe(1);
expect(list.peekBack()).toBe(3);
});
});
describe('pushBack', () => {
it('should append to empty list', () => {
const list = new LinkedList<number>();
const node = list.pushBack(1);
expect(list.length).toBe(1);
expect(node.value).toBe(1);
expect(list.head).toBe(node);
expect(list.tail).toBe(node);
});
it('should append to non-empty list', () => {
const list = new LinkedList([1, 2]);
list.pushBack(3);
expect(list.length).toBe(3);
expect(list.peekBack()).toBe(3);
expect(list.peekFront()).toBe(1);
});
it('should return the created node', () => {
const list = new LinkedList<number>();
const node = list.pushBack(5);
expect(node.value).toBe(5);
expect(node.prev).toBeUndefined();
expect(node.next).toBeUndefined();
});
});
describe('pushFront', () => {
it('should prepend to empty list', () => {
const list = new LinkedList<number>();
const node = list.pushFront(1);
expect(list.length).toBe(1);
expect(list.head).toBe(node);
expect(list.tail).toBe(node);
});
it('should prepend to non-empty list', () => {
const list = new LinkedList([2, 3]);
list.pushFront(1);
expect(list.length).toBe(3);
expect(list.peekFront()).toBe(1);
expect(list.peekBack()).toBe(3);
});
});
describe('popBack', () => {
it('should return undefined for empty list', () => {
const list = new LinkedList<number>();
expect(list.popBack()).toBeUndefined();
});
it('should remove and return last value', () => {
const list = new LinkedList([1, 2, 3]);
expect(list.popBack()).toBe(3);
expect(list.length).toBe(2);
expect(list.peekBack()).toBe(2);
});
it('should handle single element', () => {
const list = new LinkedList(1);
expect(list.popBack()).toBe(1);
expect(list.isEmpty).toBe(true);
expect(list.head).toBeUndefined();
expect(list.tail).toBeUndefined();
});
});
describe('popFront', () => {
it('should return undefined for empty list', () => {
const list = new LinkedList<number>();
expect(list.popFront()).toBeUndefined();
});
it('should remove and return first value', () => {
const list = new LinkedList([1, 2, 3]);
expect(list.popFront()).toBe(1);
expect(list.length).toBe(2);
expect(list.peekFront()).toBe(2);
});
it('should handle single element', () => {
const list = new LinkedList(1);
expect(list.popFront()).toBe(1);
expect(list.isEmpty).toBe(true);
expect(list.head).toBeUndefined();
expect(list.tail).toBeUndefined();
});
});
describe('peekBack', () => {
it('should return undefined for empty list', () => {
const list = new LinkedList<number>();
expect(list.peekBack()).toBeUndefined();
});
it('should return last value without removing', () => {
const list = new LinkedList([1, 2, 3]);
expect(list.peekBack()).toBe(3);
expect(list.length).toBe(3);
});
});
describe('peekFront', () => {
it('should return undefined for empty list', () => {
const list = new LinkedList<number>();
expect(list.peekFront()).toBeUndefined();
});
it('should return first value without removing', () => {
const list = new LinkedList([1, 2, 3]);
expect(list.peekFront()).toBe(1);
expect(list.length).toBe(3);
});
});
describe('insertBefore', () => {
it('should insert before head', () => {
const list = new LinkedList<number>();
const node = list.pushBack(2);
list.insertBefore(node, 1);
expect(list.peekFront()).toBe(1);
expect(list.peekBack()).toBe(2);
expect(list.length).toBe(2);
});
it('should insert before middle node', () => {
const list = new LinkedList([1, 3]);
const tail = list.tail!;
list.insertBefore(tail, 2);
expect(list.toArray()).toEqual([1, 2, 3]);
});
it('should return the created node', () => {
const list = new LinkedList<number>();
const existing = list.pushBack(2);
const newNode = list.insertBefore(existing, 1);
expect(newNode.value).toBe(1);
expect(newNode.next).toBe(existing);
});
});
describe('insertAfter', () => {
it('should insert after tail', () => {
const list = new LinkedList<number>();
const node = list.pushBack(1);
list.insertAfter(node, 2);
expect(list.peekFront()).toBe(1);
expect(list.peekBack()).toBe(2);
expect(list.length).toBe(2);
});
it('should insert after middle node', () => {
const list = new LinkedList([1, 3]);
const head = list.head!;
list.insertAfter(head, 2);
expect(list.toArray()).toEqual([1, 2, 3]);
});
it('should return the created node', () => {
const list = new LinkedList<number>();
const existing = list.pushBack(1);
const newNode = list.insertAfter(existing, 2);
expect(newNode.value).toBe(2);
expect(newNode.prev).toBe(existing);
});
});
describe('remove', () => {
it('should remove head node', () => {
const list = new LinkedList([1, 2, 3]);
const head = list.head!;
const value = list.remove(head);
expect(value).toBe(1);
expect(list.length).toBe(2);
expect(list.peekFront()).toBe(2);
});
it('should remove tail node', () => {
const list = new LinkedList([1, 2, 3]);
const tail = list.tail!;
const value = list.remove(tail);
expect(value).toBe(3);
expect(list.length).toBe(2);
expect(list.peekBack()).toBe(2);
});
it('should remove middle node', () => {
const list = new LinkedList([1, 2, 3]);
const middle = list.head!.next!;
const value = list.remove(middle);
expect(value).toBe(2);
expect(list.toArray()).toEqual([1, 3]);
});
it('should remove single element', () => {
const list = new LinkedList<number>();
const node = list.pushBack(1);
list.remove(node);
expect(list.isEmpty).toBe(true);
expect(list.head).toBeUndefined();
expect(list.tail).toBeUndefined();
});
it('should detach the removed node', () => {
const list = new LinkedList([1, 2, 3]);
const middle = list.head!.next!;
list.remove(middle);
expect(middle.prev).toBeUndefined();
expect(middle.next).toBeUndefined();
});
});
describe('clear', () => {
it('should remove all elements', () => {
const list = new LinkedList([1, 2, 3]);
const result = list.clear();
expect(list.length).toBe(0);
expect(list.isEmpty).toBe(true);
expect(list.head).toBeUndefined();
expect(list.tail).toBeUndefined();
expect(result).toBe(list);
});
});
describe('toArray', () => {
it('should return empty array for empty list', () => {
const list = new LinkedList<number>();
expect(list.toArray()).toEqual([]);
});
it('should return values from head to tail', () => {
const list = new LinkedList([1, 2, 3]);
expect(list.toArray()).toEqual([1, 2, 3]);
});
});
describe('toString', () => {
it('should return comma-separated values', () => {
const list = new LinkedList([1, 2, 3]);
expect(list.toString()).toBe('1,2,3');
});
});
describe('iterator', () => {
it('should iterate from head to tail', () => {
const list = new LinkedList([1, 2, 3]);
expect([...list]).toEqual([1, 2, 3]);
});
it('should yield nothing for empty list', () => {
const list = new LinkedList<number>();
expect([...list]).toEqual([]);
});
});
describe('async iterator', () => {
it('should async iterate from head to tail', async () => {
const list = new LinkedList([1, 2, 3]);
const result: number[] = [];
for await (const value of list)
result.push(value);
expect(result).toEqual([1, 2, 3]);
});
});
describe('node linking', () => {
it('should maintain correct prev/next references', () => {
const list = new LinkedList<number>();
const a = list.pushBack(1);
const b = list.pushBack(2);
const c = list.pushBack(3);
expect(a.next).toBe(b);
expect(b.prev).toBe(a);
expect(b.next).toBe(c);
expect(c.prev).toBe(b);
expect(a.prev).toBeUndefined();
expect(c.next).toBeUndefined();
});
it('should update links after removal', () => {
const list = new LinkedList<number>();
const a = list.pushBack(1);
const b = list.pushBack(2);
const c = list.pushBack(3);
list.remove(b);
expect(a.next).toBe(c);
expect(c.prev).toBe(a);
});
});
describe('interleaved operations', () => {
it('should handle mixed push/pop from both ends', () => {
const list = new LinkedList<number>();
list.pushBack(1);
list.pushBack(2);
list.pushFront(0);
expect(list.popFront()).toBe(0);
expect(list.popBack()).toBe(2);
expect(list.popFront()).toBe(1);
expect(list.isEmpty).toBe(true);
});
it('should handle insert and remove by node reference', () => {
const list = new LinkedList<number>();
const a = list.pushBack(1);
const c = list.pushBack(3);
const b = list.insertAfter(a, 2);
const d = list.insertBefore(c, 2.5);
expect(list.toArray()).toEqual([1, 2, 2.5, 3]);
list.remove(b);
list.remove(d);
expect(list.toArray()).toEqual([1, 3]);
});
});
});

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import { isArray } from '../../types';
import type { LinkedListLike, LinkedListNode } from './types';
export type { LinkedListLike, LinkedListNode } from './types';
/**
* Creates a new doubly linked list node
*
* @template T The type of the value
* @param {T} value The value to store
* @returns {LinkedListNode<T>} The created node
*/
function createNode<T>(value: T): LinkedListNode<T> {
return { value, prev: undefined, next: undefined };
}
/**
* @name LinkedList
* @category Data Structures
* @description Doubly linked list with O(1) push/pop on both ends and O(1) insert/remove by node reference
*
* @since 0.0.8
*
* @template T The type of elements stored in the list
*/
export class LinkedList<T> implements LinkedListLike<T> {
/**
* The number of elements in the list
*
* @private
* @type {number}
*/
private count: number = 0;
/**
* The first node in the list
*
* @private
* @type {LinkedListNode<T> | undefined}
*/
private first: LinkedListNode<T> | undefined;
/**
* The last node in the list
*
* @private
* @type {LinkedListNode<T> | undefined}
*/
private last: LinkedListNode<T> | undefined;
/**
* Creates an instance of LinkedList
*
* @param {(T[] | T)} [initialValues] The initial values to add to the list
*/
constructor(initialValues?: T[] | T) {
if (initialValues != null) {
const items = isArray(initialValues) ? initialValues : [initialValues];
for (const item of items)
this.pushBack(item);
}
}
/**
* Gets the number of elements in the list
* @returns {number} The number of elements in the list
*/
public get length(): number {
return this.count;
}
/**
* Checks if the list is empty
* @returns {boolean} `true` if the list is empty, `false` otherwise
*/
public get isEmpty(): boolean {
return this.count === 0;
}
/**
* Gets the first node
* @returns {LinkedListNode<T> | undefined} The first node, or `undefined` if the list is empty
*/
public get head(): LinkedListNode<T> | undefined {
return this.first;
}
/**
* Gets the last node
* @returns {LinkedListNode<T> | undefined} The last node, or `undefined` if the list is empty
*/
public get tail(): LinkedListNode<T> | undefined {
return this.last;
}
/**
* Appends a value to the end of the list
* @param {T} value The value to append
* @returns {LinkedListNode<T>} The created node
*/
public pushBack(value: T): LinkedListNode<T> {
const node = createNode(value);
if (this.last) {
node.prev = this.last;
this.last.next = node;
this.last = node;
} else {
this.first = node;
this.last = node;
}
this.count++;
return node;
}
/**
* Prepends a value to the beginning of the list
* @param {T} value The value to prepend
* @returns {LinkedListNode<T>} The created node
*/
public pushFront(value: T): LinkedListNode<T> {
const node = createNode(value);
if (this.first) {
node.next = this.first;
this.first.prev = node;
this.first = node;
} else {
this.first = node;
this.last = node;
}
this.count++;
return node;
}
/**
* Removes and returns the last value
* @returns {T | undefined} The last value, or `undefined` if the list is empty
*/
public popBack(): T | undefined {
if (!this.last) return undefined;
const node = this.last;
this.detach(node);
return node.value;
}
/**
* Removes and returns the first value
* @returns {T | undefined} The first value, or `undefined` if the list is empty
*/
public popFront(): T | undefined {
if (!this.first) return undefined;
const node = this.first;
this.detach(node);
return node.value;
}
/**
* Returns the last value without removing it
* @returns {T | undefined} The last value, or `undefined` if the list is empty
*/
public peekBack(): T | undefined {
return this.last?.value;
}
/**
* Returns the first value without removing it
* @returns {T | undefined} The first value, or `undefined` if the list is empty
*/
public peekFront(): T | undefined {
return this.first?.value;
}
/**
* Inserts a value before the given node
* @param {LinkedListNode<T>} node The reference node
* @param {T} value The value to insert
* @returns {LinkedListNode<T>} The created node
*/
public insertBefore(node: LinkedListNode<T>, value: T): LinkedListNode<T> {
const newNode = createNode(value);
newNode.next = node;
newNode.prev = node.prev;
if (node.prev) {
node.prev.next = newNode;
} else {
this.first = newNode;
}
node.prev = newNode;
this.count++;
return newNode;
}
/**
* Inserts a value after the given node
* @param {LinkedListNode<T>} node The reference node
* @param {T} value The value to insert
* @returns {LinkedListNode<T>} The created node
*/
public insertAfter(node: LinkedListNode<T>, value: T): LinkedListNode<T> {
const newNode = createNode(value);
newNode.prev = node;
newNode.next = node.next;
if (node.next) {
node.next.prev = newNode;
} else {
this.last = newNode;
}
node.next = newNode;
this.count++;
return newNode;
}
/**
* Removes a node from the list by reference in O(1)
* @param {LinkedListNode<T>} node The node to remove
* @returns {T} The value of the removed node
*/
public remove(node: LinkedListNode<T>): T {
this.detach(node);
return node.value;
}
/**
* Removes all elements from the list
* @returns {this} The list instance for chaining
*/
public clear(): this {
this.first = undefined;
this.last = undefined;
this.count = 0;
return this;
}
/**
* Returns a shallow copy of the list values as an array
* @returns {T[]} Array of values from head to tail
*/
public toArray(): T[] {
const result = new Array<T>(this.count);
let current = this.first;
let i = 0;
while (current) {
result[i++] = current.value;
current = current.next;
}
return result;
}
/**
* Returns a string representation of the list
* @returns {string} String representation
*/
public toString(): string {
return this.toArray().toString();
}
/**
* Iterator over list values from head to tail
*/
public *[Symbol.iterator](): Iterator<T> {
let current = this.first;
while (current) {
yield current.value;
current = current.next;
}
}
/**
* Async iterator over list values from head to tail
*/
public async *[Symbol.asyncIterator](): AsyncIterator<T> {
for (const value of this)
yield value;
}
/**
* Detaches a node from the list, updating head/tail and count
*
* @private
* @param {LinkedListNode<T>} node The node to detach
*/
private detach(node: LinkedListNode<T>): void {
if (node.prev) {
node.prev.next = node.next;
} else {
this.first = node.next;
}
if (node.next) {
node.next.prev = node.prev;
} else {
this.last = node.prev;
}
node.prev = undefined;
node.next = undefined;
this.count--;
}
}

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@@ -0,0 +1,28 @@
export interface LinkedListNode<T> {
value: T;
prev: LinkedListNode<T> | undefined;
next: LinkedListNode<T> | undefined;
}
export interface LinkedListLike<T> extends Iterable<T>, AsyncIterable<T> {
readonly length: number;
readonly isEmpty: boolean;
readonly head: LinkedListNode<T> | undefined;
readonly tail: LinkedListNode<T> | undefined;
pushBack(value: T): LinkedListNode<T>;
pushFront(value: T): LinkedListNode<T>;
popBack(): T | undefined;
popFront(): T | undefined;
peekBack(): T | undefined;
peekFront(): T | undefined;
insertBefore(node: LinkedListNode<T>, value: T): LinkedListNode<T>;
insertAfter(node: LinkedListNode<T>, value: T): LinkedListNode<T>;
remove(node: LinkedListNode<T>): T;
clear(): this;
toArray(): T[];
toString(): string;
}

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@@ -0,0 +1,213 @@
import { describe, expect, it } from 'vitest';
import { PriorityQueue } from '.';
describe('PriorityQueue', () => {
describe('constructor', () => {
it('should create an empty queue', () => {
const pq = new PriorityQueue<number>();
expect(pq.length).toBe(0);
expect(pq.isEmpty).toBe(true);
expect(pq.isFull).toBe(false);
});
it('should create a queue from single value', () => {
const pq = new PriorityQueue(42);
expect(pq.length).toBe(1);
expect(pq.peek()).toBe(42);
});
it('should create a queue from array', () => {
const pq = new PriorityQueue([5, 3, 8, 1, 4]);
expect(pq.length).toBe(5);
expect(pq.peek()).toBe(1);
});
it('should throw if initial values exceed maxSize', () => {
expect(() => new PriorityQueue([1, 2, 3], { maxSize: 2 }))
.toThrow('Initial values exceed maxSize');
});
});
describe('enqueue', () => {
it('should enqueue elements by priority', () => {
const pq = new PriorityQueue<number>();
pq.enqueue(5);
pq.enqueue(1);
pq.enqueue(3);
expect(pq.peek()).toBe(1);
expect(pq.length).toBe(3);
});
it('should throw when queue is full', () => {
const pq = new PriorityQueue<number>(undefined, { maxSize: 2 });
pq.enqueue(1);
pq.enqueue(2);
expect(() => pq.enqueue(3)).toThrow('PriorityQueue is full');
});
});
describe('dequeue', () => {
it('should return undefined for empty queue', () => {
const pq = new PriorityQueue<number>();
expect(pq.dequeue()).toBeUndefined();
});
it('should dequeue elements in priority order (min-heap)', () => {
const pq = new PriorityQueue([5, 3, 8, 1, 4]);
const result: number[] = [];
while (!pq.isEmpty) {
result.push(pq.dequeue()!);
}
expect(result).toEqual([1, 3, 4, 5, 8]);
});
it('should dequeue elements in priority order (max-heap)', () => {
const pq = new PriorityQueue([5, 3, 8, 1, 4], {
comparator: (a, b) => b - a,
});
const result: number[] = [];
while (!pq.isEmpty) {
result.push(pq.dequeue()!);
}
expect(result).toEqual([8, 5, 4, 3, 1]);
});
});
describe('peek', () => {
it('should return undefined for empty queue', () => {
const pq = new PriorityQueue<number>();
expect(pq.peek()).toBeUndefined();
});
it('should return highest-priority element without removing', () => {
const pq = new PriorityQueue([5, 1, 3]);
expect(pq.peek()).toBe(1);
expect(pq.length).toBe(3);
});
});
describe('isFull', () => {
it('should be false when no maxSize', () => {
const pq = new PriorityQueue([1, 2, 3]);
expect(pq.isFull).toBe(false);
});
it('should be true when at maxSize', () => {
const pq = new PriorityQueue([1, 2], { maxSize: 2 });
expect(pq.isFull).toBe(true);
});
it('should become false after dequeue', () => {
const pq = new PriorityQueue([1, 2], { maxSize: 2 });
pq.dequeue();
expect(pq.isFull).toBe(false);
});
});
describe('clear', () => {
it('should remove all elements', () => {
const pq = new PriorityQueue([1, 2, 3]);
const result = pq.clear();
expect(pq.length).toBe(0);
expect(pq.isEmpty).toBe(true);
expect(result).toBe(pq);
});
});
describe('toArray', () => {
it('should return empty array for empty queue', () => {
const pq = new PriorityQueue<number>();
expect(pq.toArray()).toEqual([]);
});
it('should return a shallow copy', () => {
const pq = new PriorityQueue([3, 1, 2]);
const arr = pq.toArray();
arr.push(99);
expect(pq.length).toBe(3);
});
});
describe('toString', () => {
it('should return formatted string', () => {
const pq = new PriorityQueue([1, 2, 3]);
expect(pq.toString()).toBe('PriorityQueue(3)');
});
});
describe('iterator', () => {
it('should iterate over elements', () => {
const pq = new PriorityQueue([5, 3, 1]);
const elements = [...pq];
expect(elements.length).toBe(3);
});
});
describe('custom comparator', () => {
it('should work with object priority', () => {
interface Job {
priority: number;
name: string;
}
const pq = new PriorityQueue<Job>(
[
{ priority: 3, name: 'low' },
{ priority: 1, name: 'critical' },
{ priority: 2, name: 'normal' },
],
{ comparator: (a, b) => a.priority - b.priority },
);
expect(pq.dequeue()?.name).toBe('critical');
expect(pq.dequeue()?.name).toBe('normal');
expect(pq.dequeue()?.name).toBe('low');
});
});
describe('interleaved operations', () => {
it('should maintain priority with mixed enqueue and dequeue', () => {
const pq = new PriorityQueue<number>();
pq.enqueue(10);
pq.enqueue(5);
expect(pq.dequeue()).toBe(5);
pq.enqueue(3);
pq.enqueue(7);
expect(pq.dequeue()).toBe(3);
pq.enqueue(1);
expect(pq.dequeue()).toBe(1);
expect(pq.dequeue()).toBe(7);
expect(pq.dequeue()).toBe(10);
expect(pq.dequeue()).toBeUndefined();
});
});
});

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@@ -0,0 +1,144 @@
import { BinaryHeap } from '../BinaryHeap';
import type { Comparator, PriorityQueueLike } from './types';
export type { PriorityQueueLike } from './types';
export type { Comparator } from './types';
export interface PriorityQueueOptions<T> {
comparator?: Comparator<T>;
maxSize?: number;
}
/**
* @name PriorityQueue
* @category Data Structures
* @description Priority queue backed by a binary heap with configurable comparator and optional max size
*
* @since 0.0.8
*
* @template T The type of elements stored in the queue
*/
export class PriorityQueue<T> implements PriorityQueueLike<T> {
/**
* The maximum number of elements the queue can hold
*
* @private
* @type {number}
*/
private readonly maxSize: number;
/**
* Internal binary heap backing the queue
*
* @private
* @type {BinaryHeap<T>}
*/
private readonly heap: BinaryHeap<T>;
/**
* Creates an instance of PriorityQueue
*
* @param {(T[] | T)} [initialValues] The initial values to add to the queue
* @param {PriorityQueueOptions<T>} [options] Queue configuration
*/
constructor(initialValues?: T[] | T, options?: PriorityQueueOptions<T>) {
this.maxSize = options?.maxSize ?? Infinity;
this.heap = new BinaryHeap(initialValues, { comparator: options?.comparator });
if (this.heap.length > this.maxSize) {
throw new RangeError('Initial values exceed maxSize');
}
}
/**
* Gets the number of elements in the queue
* @returns {number} The number of elements in the queue
*/
public get length(): number {
return this.heap.length;
}
/**
* Checks if the queue is empty
* @returns {boolean} `true` if the queue is empty, `false` otherwise
*/
public get isEmpty(): boolean {
return this.heap.isEmpty;
}
/**
* Checks if the queue is full
* @returns {boolean} `true` if the queue has reached maxSize, `false` otherwise
*/
public get isFull(): boolean {
return this.heap.length >= this.maxSize;
}
/**
* Enqueues an element by priority
* @param {T} element The element to enqueue
* @throws {RangeError} If the queue is full
*/
public enqueue(element: T): void {
if (this.isFull)
throw new RangeError('PriorityQueue is full');
this.heap.push(element);
}
/**
* Dequeues the highest-priority element
* @returns {T | undefined} The highest-priority element, or `undefined` if empty
*/
public dequeue(): T | undefined {
return this.heap.pop();
}
/**
* Returns the highest-priority element without removing it
* @returns {T | undefined} The highest-priority element, or `undefined` if empty
*/
public peek(): T | undefined {
return this.heap.peek();
}
/**
* Removes all elements from the queue
* @returns {this} The queue instance for chaining
*/
public clear(): this {
this.heap.clear();
return this;
}
/**
* Returns a shallow copy of elements in heap order
* @returns {T[]} Array of elements
*/
public toArray(): T[] {
return this.heap.toArray();
}
/**
* Returns a string representation of the queue
* @returns {string} String representation
*/
public toString(): string {
return `PriorityQueue(${this.heap.length})`;
}
/**
* Iterator over queue elements in heap order
*/
public *[Symbol.iterator](): Iterator<T> {
yield* this.heap;
}
/**
* Async iterator over queue elements in heap order
*/
public async *[Symbol.asyncIterator](): AsyncIterator<T> {
for (const element of this.heap)
yield element;
}
}

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@@ -0,0 +1,16 @@
import type { Comparator } from '../BinaryHeap';
export interface PriorityQueueLike<T> extends Iterable<T>, AsyncIterable<T> {
readonly length: number;
readonly isEmpty: boolean;
readonly isFull: boolean;
enqueue(element: T): void;
dequeue(): T | undefined;
peek(): T | undefined;
clear(): this;
toArray(): T[];
toString(): string;
}
export type { Comparator };

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@@ -0,0 +1,207 @@
import { describe, it, expect } from 'vitest';
import { Queue } from '.';
describe('queue', () => {
describe('constructor', () => {
it('create an empty queue if no initial values are provided', () => {
const queue = new Queue<number>();
expect(queue.length).toBe(0);
expect(queue.isEmpty).toBe(true);
});
it('create a queue with the provided initial values', () => {
const queue = new Queue([1, 2, 3]);
expect(queue.length).toBe(3);
expect(queue.peek()).toBe(1);
});
it('create a queue with a single initial value', () => {
const queue = new Queue(42);
expect(queue.length).toBe(1);
expect(queue.peek()).toBe(42);
});
it('create a queue with the provided options', () => {
const queue = new Queue<number>(undefined, { maxSize: 5 });
expect(queue.length).toBe(0);
expect(queue.isFull).toBe(false);
});
});
describe('enqueue', () => {
it('add an element to the back of the queue', () => {
const queue = new Queue<number>();
queue.enqueue(1);
expect(queue.length).toBe(1);
expect(queue.peek()).toBe(1);
});
it('maintain FIFO order', () => {
const queue = new Queue<number>();
queue.enqueue(1).enqueue(2).enqueue(3);
expect(queue.peek()).toBe(1);
});
it('throw an error if the queue is full', () => {
const queue = new Queue<number>(undefined, { maxSize: 1 });
queue.enqueue(1);
expect(() => queue.enqueue(2)).toThrow(new RangeError('Queue is full'));
});
it('return this for chaining', () => {
const queue = new Queue<number>();
const result = queue.enqueue(1);
expect(result).toBe(queue);
});
});
describe('dequeue', () => {
it('remove and return the front element', () => {
const queue = new Queue([1, 2, 3]);
const element = queue.dequeue();
expect(element).toBe(1);
expect(queue.length).toBe(2);
});
it('return undefined if the queue is empty', () => {
const queue = new Queue<number>();
expect(queue.dequeue()).toBeUndefined();
});
it('maintain FIFO order across multiple dequeues', () => {
const queue = new Queue([1, 2, 3]);
expect(queue.dequeue()).toBe(1);
expect(queue.dequeue()).toBe(2);
expect(queue.dequeue()).toBe(3);
expect(queue.dequeue()).toBeUndefined();
});
it('compact internal storage after many dequeues', () => {
const queue = new Queue<number>();
for (let i = 0; i < 100; i++)
queue.enqueue(i);
for (let i = 0; i < 80; i++)
queue.dequeue();
expect(queue.length).toBe(20);
expect(queue.peek()).toBe(80);
});
});
describe('peek', () => {
it('return the front element without removing it', () => {
const queue = new Queue([1, 2, 3]);
expect(queue.peek()).toBe(1);
expect(queue.length).toBe(3);
});
it('return undefined if the queue is empty', () => {
const queue = new Queue<number>();
expect(queue.peek()).toBeUndefined();
});
});
describe('clear', () => {
it('clear the queue', () => {
const queue = new Queue([1, 2, 3]);
queue.clear();
expect(queue.length).toBe(0);
expect(queue.isEmpty).toBe(true);
});
it('return this for chaining', () => {
const queue = new Queue([1, 2, 3]);
expect(queue.clear()).toBe(queue);
});
});
describe('toArray', () => {
it('return elements in FIFO order', () => {
const queue = new Queue([1, 2, 3]);
expect(queue.toArray()).toEqual([1, 2, 3]);
});
it('return correct array after dequeues', () => {
const queue = new Queue([1, 2, 3, 4, 5]);
queue.dequeue();
queue.dequeue();
expect(queue.toArray()).toEqual([3, 4, 5]);
});
});
describe('toString', () => {
it('return comma-separated string', () => {
const queue = new Queue([1, 2, 3]);
expect(queue.toString()).toBe('1,2,3');
});
});
describe('iteration', () => {
it('iterate over the queue in FIFO order', () => {
const queue = new Queue([1, 2, 3]);
expect([...queue]).toEqual([1, 2, 3]);
});
it('iterate correctly after dequeues', () => {
const queue = new Queue([1, 2, 3, 4]);
queue.dequeue();
expect([...queue]).toEqual([2, 3, 4]);
});
it('iterate over the queue asynchronously in FIFO order', async () => {
const queue = new Queue([1, 2, 3]);
const elements: number[] = [];
for await (const element of queue)
elements.push(element);
expect(elements).toEqual([1, 2, 3]);
});
});
describe('mixed operations', () => {
it('interleave enqueue and dequeue', () => {
const queue = new Queue<number>();
queue.enqueue(1);
queue.enqueue(2);
expect(queue.dequeue()).toBe(1);
queue.enqueue(3);
expect(queue.dequeue()).toBe(2);
expect(queue.dequeue()).toBe(3);
expect(queue.isEmpty).toBe(true);
});
it('reuse queue after clear', () => {
const queue = new Queue([1, 2, 3]);
queue.clear();
queue.enqueue(4);
expect(queue.length).toBe(1);
expect(queue.peek()).toBe(4);
});
});
});

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@@ -0,0 +1,140 @@
import { Deque } from '../Deque';
import type { QueueLike } from './types';
export type { QueueLike } from './types';
export interface QueueOptions {
maxSize?: number;
}
/**
* @name Queue
* @category Data Structures
* @description Represents a queue data structure (FIFO) backed by a Deque
*
* @since 0.0.8
*
* @template T The type of elements stored in the queue
*/
export class Queue<T> implements QueueLike<T> {
/**
* The underlying deque
*
* @private
* @type {Deque<T>}
*/
private readonly deque: Deque<T>;
/**
* Creates an instance of Queue
*
* @param {(T[] | T)} [initialValues] The initial values to add to the queue
* @param {QueueOptions} [options] The options for the queue
*/
constructor(initialValues?: T[] | T, options?: QueueOptions) {
this.deque = new Deque(initialValues, options);
}
/**
* Gets the number of elements in the queue
* @returns {number} The number of elements in the queue
*/
get length() {
return this.deque.length;
}
/**
* Checks if the queue is empty
* @returns {boolean} `true` if the queue is empty, `false` otherwise
*/
get isEmpty() {
return this.deque.isEmpty;
}
/**
* Checks if the queue is full
* @returns {boolean} `true` if the queue is full, `false` otherwise
*/
get isFull() {
return this.deque.isFull;
}
/**
* Adds an element to the back of the queue
* @param {T} element The element to enqueue
* @returns {this}
* @throws {RangeError} If the queue is full
*/
enqueue(element: T) {
if (this.deque.isFull)
throw new RangeError('Queue is full');
this.deque.pushBack(element);
return this;
}
/**
* Removes and returns the front element of the queue
* @returns {T | undefined} The front element, or undefined if the queue is empty
*/
dequeue() {
return this.deque.popFront();
}
/**
* Returns the front element without removing it
* @returns {T | undefined} The front element, or undefined if the queue is empty
*/
peek() {
return this.deque.peekFront();
}
/**
* Clears the queue
*
* @returns {this}
*/
clear() {
this.deque.clear();
return this;
}
/**
* Converts the queue to an array in FIFO order
*
* @returns {T[]}
*/
toArray() {
return this.deque.toArray();
}
/**
* Returns a string representation of the queue
*
* @returns {string}
*/
toString() {
return this.deque.toString();
}
/**
* Returns an iterator for the queue
*
* @returns {IterableIterator<T>}
*/
[Symbol.iterator]() {
return this.deque[Symbol.iterator]();
}
/**
* Returns an async iterator for the queue
*
* @returns {AsyncIterableIterator<T>}
*/
async *[Symbol.asyncIterator]() {
for (const element of this.deque)
yield element;
}
}

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@@ -0,0 +1,12 @@
export interface QueueLike<T> extends Iterable<T>, AsyncIterable<T> {
readonly length: number;
readonly isEmpty: boolean;
readonly isFull: boolean;
enqueue(element: T): this;
dequeue(): T | undefined;
peek(): T | undefined;
clear(): this;
toArray(): T[];
toString(): string;
}

View File

@@ -1 +1,7 @@
export * from './stack';
export * from './BinaryHeap';
export * from './CircularBuffer';
export * from './Deque';
export * from './LinkedList';
export * from './PriorityQueue';
export * from './Queue';
export * from './Stack';

View File

@@ -1,5 +1,8 @@
import { last } from '../../arrays';
import { isArray } from '../../types';
import type { StackLike } from './types';
export type { StackLike } from './types';
export interface StackOptions {
maxSize?: number;
@@ -14,7 +17,7 @@ export interface StackOptions {
*
* @template T The type of elements stored in the stack
*/
export class Stack<T> implements Iterable<T>, AsyncIterable<T> {
export class Stack<T> implements StackLike<T> {
/**
* The maximum number of elements that the stack can hold
*

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@@ -0,0 +1,12 @@
export interface StackLike<T> extends Iterable<T>, AsyncIterable<T> {
readonly length: number;
readonly isEmpty: boolean;
readonly isFull: boolean;
push(element: T): this;
pop(): T | undefined;
peek(): T | undefined;
clear(): this;
toArray(): T[];
toString(): string;
}