labyrinth-game-logic/src/Cyrb64.ts

A libary that implements the boardgame labyrinth and exposes the functionality to create and interact with games

// cyrb53 (c) 2018 bryc (github.com/bryc). License: Public domain. Attribution appreciated.
// A fast and simple 64-bit (or 53-bit) string hash function with decent collision resistance.
// Largely inspired by MurmurHash2/3, but with a focus on speed/simplicity.
// See https://stackoverflow.com/questions/7616461/generate-a-hash-from-string-in-javascript/52171480#52171480
// https://github.com/bryc/code/blob/master/jshash/experimental/cyrb53.js

/**
 * Immutable Cyrb64 Hash class using the
 */
export class Cyrb64 {
  private readonly a: number;
  private readonly b: number;

  public constructor(a: number, b: number) {
    this.a = a;
    this.b = b;
  }

  public static hashString(str: string, seed: number): Cyrb64 {
    let h1 = 0xdeadbeef ^ seed,
      h2 = 0x41c6ce57 ^ seed;
    for (let i = 0, ch; i < str.length; i++) {
      ch = str.charCodeAt(i);
      h1 = Math.imul(h1 ^ ch, 2654435761);
      h2 = Math.imul(h2 ^ ch, 1597334677);
    }
    h1 = Math.imul(h1 ^ (h1 >>> 16), 2246822507);
    h1 ^= Math.imul(h2 ^ (h2 >>> 13), 3266489909);
    h2 = Math.imul(h2 ^ (h2 >>> 16), 2246822507);
    h2 ^= Math.imul(h1 ^ (h1 >>> 13), 3266489909);
    // For a single 53-bit numeric return value we could return
    // 4294967296 * (2097151 & h2) + (h1 >>> 0);
    // but we instead return the full 64-bit value:
    return new Cyrb64(h2 >>> 0, h1 >>> 0);
  }

  public equals(other: Cyrb64): boolean {
    return this.a === other.a && this.b === other.b;
  }
}