From 770bfb1f2eec42d1c0430f0da02df83a4827df47 Mon Sep 17 00:00:00 2001
From: Lyss <shaitan.lyssm@gmail.com>
Date: Sat, 20 Jul 2024 15:10:56 +0200
Subject: [PATCH] Add queue

---
 package.json                  |  2 +-
 src/lib/datastructure.test.ts | 50 +++++++++++++++++++++++++++++++++++
 src/lib/datastructure.ts      | 42 +++++++++++++++++++++++++++++
 src/lib/index.ts              |  4 ++-
 4 files changed, 96 insertions(+), 2 deletions(-)
 create mode 100644 src/lib/datastructure.test.ts
 create mode 100644 src/lib/datastructure.ts

diff --git a/package.json b/package.json
index 4f0c0ba..229eaf1 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@selenite/commons",
-  "version": "0.8.5",
+  "version": "0.9.0",
   "scripts": {
     "dev": "npm run wasm && vite dev",
     "wasm": "wasm-pack build ./selenite-commons-rs --target web",
diff --git a/src/lib/datastructure.test.ts b/src/lib/datastructure.test.ts
new file mode 100644
index 0000000..85e341a
--- /dev/null
+++ b/src/lib/datastructure.test.ts
@@ -0,0 +1,50 @@
+import { describe, test, expect } from 'vitest';
+import { Queue } from './datastructure';
+
+describe('datastructures', () => {
+	describe('queue', () => {
+        test('queue sizes should be valid', () => {
+            const queue = new Queue<number>()
+            expect(queue.size).toBe(0)
+            queue.add(1)
+            expect(queue.size).toBe(1)
+            queue.add(2)
+            expect(queue.size).toBe(2)
+            queue.remove()
+            expect(queue.size).toBe(1)
+            queue.remove()
+            expect(queue.size).toBe(0)
+        })
+		test('should be FIFO', () => {
+			const queue = new Queue([1, 2, 3]);
+			let res: number[] = [];
+            let c = 0
+			while (queue.size > 0) {
+                c++
+                if (c > 3) {
+                    throw new Error("Too many iterations.")
+                }
+				res.push(queue.remove());
+			}
+			expect(res).toEqual([1, 2, 3]);
+		});
+		test('should error on peek empty queue', () => {
+			const queue = new Queue();
+			expect(() => queue.peek()).toThrowError("Can't peek, queue is empty.");
+		});
+        test('should error on remove empty queue', () => {
+			const queue = new Queue();
+			expect(() => queue.remove()).toThrowError("Can't remove an element, queue is empty.");
+		})
+		test('peek should return first element without changing queue', () => {
+			const queue = new Queue([1, 2, 3]);
+			expect(queue.peek()).toBe(1);
+			expect(queue.size).toBe(3);
+		});
+		test('pop should remove first element and return it', () => {
+			const queue = new Queue([1, 2, 3]);
+			expect(queue.remove()).toBe(1);
+			expect(queue.size).toBe(2);
+		});
+	});
+});
diff --git a/src/lib/datastructure.ts b/src/lib/datastructure.ts
new file mode 100644
index 0000000..63c76af
--- /dev/null
+++ b/src/lib/datastructure.ts
@@ -0,0 +1,42 @@
+export class Queue<T> {
+	#inStack: T[] = [];
+	#outStack: T[] = [];
+
+	constructor(iterable?: Iterable<T>) {
+		if (iterable) this.#inStack.push(...iterable);
+	}
+
+	add(e: T) {
+		this.#inStack.push(e);
+	}
+
+	peek(): T {
+		this.handleEmptyOut("Can't peek, queue is empty.")
+		return this.#outStack.at(-1)!;
+	}
+
+	remove(): T {
+        this.handleEmptyOut("Can't remove an element, queue is empty.");
+		return this.#outStack.pop()!;
+	}
+
+	private handleEmptyOut(errMsg: string) {
+		if (this.#outStack.length === 0) {
+			this.swapStacks();
+		}
+		if (this.#outStack.length === 0) {
+			throw new Error(errMsg);
+		}
+	}
+
+	get size() {
+		return this.#inStack.length + this.#outStack.length;
+	}
+
+	private swapStacks() {
+		let mem = this.#outStack;
+		this.#outStack = this.#inStack;
+		this.#inStack = mem;
+		this.#outStack.reverse();
+	}
+}
diff --git a/src/lib/index.ts b/src/lib/index.ts
index 026a1c3..26615a3 100644
--- a/src/lib/index.ts
+++ b/src/lib/index.ts
@@ -25,4 +25,6 @@ export * from './actions/index.js'
 export * as Utils from './utils'
 export * from './utils/index.js'
 export * as Types from './type'
-export * from './type'
\ No newline at end of file
+export * from './type'
+export * as DataStructure from './datastructure'
+export * from './datastructure'
\ No newline at end of file