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js/base/ObjectPool.js

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+/**
+ * ObjectPool.js
+ * Generic object pool for reusing frequently created/destroyed objects
+ * (bullets, explosions, etc.) to avoid GC pressure in WeChat mini game.
+ */
+
+class ObjectPool {
+  /**
+   * @param {Function} createFn - Factory function that returns a new object instance.
+   * @param {Function} [resetFn] - Optional function to reset an object before reuse.
+   * @param {number} [initialSize=0] - Number of objects to pre-allocate.
+   */
+  constructor(createFn, resetFn, initialSize = 0) {
+    this._createFn = createFn;
+    this._resetFn = resetFn || null;
+    this._pool = [];
+    this._activeCount = 0;
+
+    // Pre-allocate
+    for (let i = 0; i < initialSize; i++) {
+      this._pool.push(this._createFn());
+    }
+  }
+
+  /**
+   * Get an object from the pool. Creates a new one if pool is empty.
+   * @returns {*} A reusable object instance.
+   */
+  get() {
+    let obj;
+    if (this._pool.length > 0) {
+      obj = this._pool.pop();
+    } else {
+      obj = this._createFn();
+    }
+    if (this._resetFn) {
+      this._resetFn(obj);
+    }
+    this._activeCount++;
+    return obj;
+  }
+
+  /**
+   * Return an object back to the pool for future reuse.
+   * @param {*} obj - The object to recycle.
+   */
+  put(obj) {
+    if (obj) {
+      this._pool.push(obj);
+      this._activeCount = Math.max(0, this._activeCount - 1);
+    }
+  }
+
+  /**
+   * Pre-allocate a number of objects into the pool.
+   * @param {number} count
+   */
+  preAllocate(count) {
+    for (let i = 0; i < count; i++) {
+      this._pool.push(this._createFn());
+    }
+  }
+
+  /**
+   * Clear the pool entirely.
+   */
+  clear() {
+    this._pool.length = 0;
+    this._activeCount = 0;
+  }
+
+  /** Number of objects currently in the pool (idle). */
+  get size() {
+    return this._pool.length;
+  }
+
+  /** Number of objects currently in use. */
+  get activeCount() {
+    return this._activeCount;
+  }
+}
+
+module.exports = ObjectPool;