iopa/src/util/freelist.ts

API-first, Internet of Things (IoT) stack for Typescript, official implementation of the Internet Open Protocols Alliance (IOPA) reference pattern

/**
 * Node 0.12.x - 4.0.x Freelist module
 *
 * Included without functional changes
 * just license notice added
 *
 * Simple function but has now been deprecated in Node.js but including here
 *
 * This license applies to this module only
 */

/**
 * Copyright Node.js contributors. All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

// This is a free list to avoid creating so many of the same object.
export default class FreeList<T> {
  public name: string

  public max: number

  private _constructor: (...args: any[]) => T

  public list: T[]

  public constructor(
    name: string,
    max: number,
    factory: (...args: any[]) => T
  ) {
    this.name = name
    this._constructor = factory
    this.max = max
    this.list = []
  }

  public alloc(...args: any[]): T {
    return this.list.length ? this.list.shift()! : this._constructor(...args)
  }

  public free(obj: T): boolean {
    if (this.list.length < this.max) {
      this.list.push(obj)
      return true
    }
    return false
  }
}