SimpleJSPriorityArray

simple-priority-array.js

// 简单的顺序队列，只能添加和迭代，并且只能支持五位数以内，数组的长度最好不要超过四位数
// 利用的是js的对象，如果key是正整数，那么在添加时可以保持大小顺序
class SimpleJSPriorityArray {
  constructor() {
    this.valcountmap = {}
    this.posmap = {}
    this.negmap = {}
    this.size = 0
  }
  get length() {
    return this.size
  }
  push(key, value = key) {
    this.valcountmap[key] ??= 0
    const count = this.valcountmap[key]++
    if (key >= 0) {
      const mapkey = '1' + key.toString().padStart(5, '0') + count.toString().padStart(4, '0')
      this.posmap[mapkey] = value
    } else {
      const mapkey = '1' + (-key).toString().padStart(5, '0') + count.toString().padStart(4, '0')
      this.negmap[mapkey] = value
    }
    this.size++
  }
  [Symbol.iterator]() {
    let poslist = null
    const neglist = Object.values(this.negmap)
    let posindex = 0
    let negindex = neglist.length - 1
    return {
      next: () => {
        if (negindex >= 0) {
          return {
            value: neglist[negindex--],
            done: false,
          }
        }
        if (!poslist) {
          poslist = Object.values(this.posmap)
        }
        if (posindex < poslist.length) {
          return {
            value: poslist[posindex++],
            done: false,
          }
        }
        return {
          value: undefined,
          done: true,
        }
      },
    }
  }
}