X-Git-Url: https://git.piment-noir.org/?a=blobdiff_plain;f=src%2Fqueue.ts;h=dba55f1cc90467ab5d27e55a9b37e9004da983b4;hb=23a6c28d3cc6edb778653a4d9d9a4d36f9a961c3;hp=11766e4e9109dc4356be0a4b589ee5e5ed9b7bd3;hpb=4d8bf9e40e07bd233be4494fda4e4270fdd8a355;p=poolifier.git

diff --git a/src/queue.ts b/src/queue.ts
index 11766e4e..dba55f1c 100644
--- a/src/queue.ts
+++ b/src/queue.ts
@@ -1,37 +1,102 @@
+// Copyright Jerome Benoit. 2021-2023. All Rights Reserved.
+
 /**
  * Queue
+ *
+ * @typeParam T - Type of queue items.
  */
 export class Queue<T> {
-  private items: Record<number, T>
-  private head: number
-  private tail: number
+  private items!: T[]
+  private offset!: number
+  /** The size of the queue. */
+  public size!: number
+  /** The maximum size of the queue. */
+  public maxSize!: number
 
   public constructor () {
-    this.items = {}
-    this.head = 0
-    this.tail = 0
-  }
-
-  public get size (): number {
-    return this.tail - this.head
+    this.clear()
   }
 
+  /**
+   * Enqueue an item.
+   *
+   * @param item - Item to enqueue.
+   * @returns The new size of the queue.
+   */
   public enqueue (item: T): number {
-    this.items[this.tail] = item
-    this.tail++
+    this.items.push(item)
+    ++this.size
+    if (this.size > this.maxSize) {
+      this.maxSize = this.size
+    }
     return this.size
   }
 
+  /**
+   * Dequeue an item.
+   *
+   * @returns The dequeued item or `undefined` if the queue is empty.
+   */
   public dequeue (): T | undefined {
-    if (this.size <= 0) return undefined
-    const item = this.items[this.head]
-    // eslint-disable-next-line @typescript-eslint/no-dynamic-delete
-    delete this.items[this.head]
-    this.head++
-    if (this.head === this.tail) {
-      this.head = 0
-      this.tail = 0
+    if (this.size <= 0) {
+      return undefined
     }
+    const item = this.items[this.offset]
+    if (++this.offset * 2 >= this.items.length) {
+      this.items = this.items.slice(this.offset)
+      this.offset = 0
+    }
+    --this.size
     return item
   }
+
+  /**
+   * Peeks at the first item.
+   *
+   * @returns The first item or `undefined` if the queue is empty.
+   */
+  public peek (): T | undefined {
+    if (this.size <= 0) {
+      return undefined
+    }
+    return this.items[this.offset]
+  }
+
+  /**
+   * Clears the queue.
+   */
+  public clear (): void {
+    this.items = []
+    this.offset = 0
+    this.size = 0
+    this.maxSize = 0
+  }
+
+  /**
+   * Returns an iterator for the queue.
+   *
+   * @returns An iterator for the queue.
+   * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols
+   */
+  [Symbol.iterator] (): Iterator<T> {
+    const items = this.items
+    let i = this.offset
+
+    return {
+      next: () => {
+        if (i >= items.length) {
+          return {
+            value: undefined,
+            done: true
+          }
+        }
+        const value = items[i]
+        ++i
+        return {
+          value,
+          done: false
+        }
+      }
+    }
+  }
 }