stickyants-bitset-js/src/ObservableBitSet.ts

A Bit vector library that mirrors Java's BitSet class

import { observable, action } from 'mobx'; 
const numberLength = 31;

export class ObservableBitSet {
  @observable.ref vector: number[] = [];

  @action.bound
  update(idx: number, val: boolean) {
    var vectorIndex = Math.floor(idx / numberLength);
    this.expand(idx); 
    if (val) {
      this.vector[vectorIndex] |= 1 << (idx % numberLength);
    } else {
      this.vector[vectorIndex] &= ~(1 << (idx % numberLength));
    }
  }

  @action.bound
  expand(idx:number){
    var updated = false; 
    var vectorIndex = Math.floor(idx / numberLength);
    if (vectorIndex >= this.vector.length) {
      var len = this.vector.length - vectorIndex;
      if (len > 0){
        updated = true; 
      }
      for (var i = 0; i < len; i++) {
        this.vector.push(0); 
      }
    }
    if (updated){
      this.vector = this.vector.slice(0); 
    }
  }

  getBit(idx: number) {
    var vectorIndex = Math.floor(idx / numberLength);
    if (vectorIndex >= this.vector.length){
      return 0; 
    }
    var val = this.vector[vectorIndex];
    return (val >> (idx % numberLength)) & 0x1;
  }

  @action.bound
  toggle(idx: number) {
    if (this.isClear(idx)) {
      this.set(idx);
    } else {
      this.clear(idx);
    }
  }

  @action.bound
  set(idx: number) {
    this.update(idx, true);
  }

  @action.bound
  clear(idx: number) {
    this.update(idx, false);
  }

  isSet(idx: number) {
    return this.getBit(idx) === 1;
  }

  isClear(idx: number) {
    return this.getBit(idx) === 0;
  }

  getValue() {
    return this.vector;
  }

  toString() {
    return this.vector.map(e => e.toString(2)).join('');
  }
}