'use strict';
/**
* An instance of `RandomDataGenerator` is exported as `engine/rnd`.
*
* @class RandomDataGenerator
*/
class RandomDataGenerator {
/**
* @constructor
* @param {Array|String} [seeds=[]] - An array of values to use as the seed, or a generator state (from {#state}).
*/
constructor(seeds = []) {
/**
* @type {number}
* @private
*/
this.c = 1;
/**
* @type {number}
* @private
*/
this.s0 = 0;
/**
* @type {number}
* @private
*/
this.s1 = 0;
/**
* @type {number}
* @private
*/
this.s2 = 0;
if (typeof(seeds) === 'string') {
this.state(seeds);
}
else {
this.sow(seeds);
}
}
/**
* Private random helper.
*
* @method RandomDataGenerator#rnd
* @private
* @return {number} Random number
*/
rnd() {
let t = 2091639 * this.s0 + this.c * 2.3283064365386963e-10; // 2^-32
this.c = t | 0;
this.s0 = this.s1;
this.s1 = this.s2;
this.s2 = t - this.c;
return this.s2;
}
/**
* Reset the seed of the random data generator.
*
* _Note_: the seed array is only processed up to the first `undefined` (or `null`) value, should such be present.
*
* @method RandomDataGenerator#sow
* @param {any[]} seeds - The array of seeds: the `toString()` of each value is used.
*/
sow(seeds) {
// Always reset to default seed
this.s0 = this.hash(' ');
this.s1 = this.hash(this.s0);
this.s2 = this.hash(this.s1);
this.c = 1;
if (!seeds) {
return;
}
// Apply any seeds
let i, seed;
for (i = 0; i < seeds.length && (seeds[i] != null); i++) {
seed = seeds[i];
this.s0 -= this.hash(seed);
this.s0 += ~~(this.s0 < 0);
this.s1 -= this.hash(seed);
this.s1 += ~~(this.s1 < 0);
this.s2 -= this.hash(seed);
this.s2 += ~~(this.s2 < 0);
}
}
/**
* Internal method that creates a seed hash.
*
* @method RandomDataGenerator#hash
* @private
* @param {any} data Data to create hash from
* @return {number} hashed value.
*/
hash(data) {
let h, i, n;
n = 0xefc8249d;
data = data.toString();
for (i = 0; i < data.length; i++) {
n += data.charCodeAt(i);
h = 0.02519603282416938 * n;
n = h >>> 0;
h -= n;
h *= n;
n = h >>> 0;
h -= n;
n += h * 0x100000000;// 2^32
}
return (n >>> 0) * 2.3283064365386963e-10;// 2^-32
}
/**
* Returns a random integer between 0 and 2^32.
*
* @method RandomDataGenerator#integer
* @return {number} A random integer between 0 and 2^32.
*/
integer() {
return this.rnd.apply(this) * 0x100000000;// 2^32
}
/**
* Returns a random real number between 0 and 1.
*
* @method RandomDataGenerator#frac
* @return {number} A random real number between 0 and 1.
*/
frac() {
return this.rnd.apply(this) + (this.rnd.apply(this) * 0x200000 | 0) * 1.1102230246251565e-16; // 2^-53
}
/**
* Returns a random real number between 0 and 2^32.
*
* @method RandomDataGenerator#real
* @return {number} A random real number between 0 and 2^32.
*/
real() {
return this.integer() + this.frac();
}
/**
* Returns a random integer between and including min and max.
*
* @method RandomDataGenerator#integerInRange
* @param {number} min - The minimum value in the range.
* @param {number} max - The maximum value in the range.
* @return {number} A random number between min and max.
*/
integerInRange(min, max) {
return Math.floor(this.realInRange(0, max - min + 1) + min);
}
/**
* Returns a random integer between and including min and max.
* This method is an alias for RandomDataGenerator.integerInRange.
*
* @method RandomDataGenerator#between
* @param {number} min - The minimum value in the range.
* @param {number} max - The maximum value in the range.
* @return {number} A random number between min and max.
*/
between(min, max) {
return this.integerInRange(min, max);
}
/**
* Returns a random real number between min and max.
*
* @method RandomDataGenerator#realInRange
* @param {number} min - The minimum value in the range.
* @param {number} max - The maximum value in the range.
* @return {number} A random number between min and max.
*/
realInRange(min, max) {
return this.frac() * (max - min) + min;
}
/**
* Returns a random real number between -1 and 1.
*
* @method RandomDataGenerator#normal
* @return {number} A random real number between -1 and 1.
*/
normal() {
return 1 - 2 * this.frac();
}
/**
* Returns a valid RFC4122 version4 ID hex string from https://gist.github.com/1308368
*
* @method RandomDataGenerator#uuid
* @return {string} A valid RFC4122 version4 ID hex string
*/
uuid() {
let a = '', b = '';
/* eslint no-empty:0*/
for (b = a = ''; a++ < 36; b += ~a % 5 | a * 3 & 4 ? (a ^ 15 ? 8 ^ this.frac() * (a ^ 20 ? 16 : 4) : 4).toString(16) : '-') {}
return b;
}
/**
* Returns a random member of `array`.
*
* @method RandomDataGenerator#pick
* @param {Array} ary - An Array to pick a random member of.
* @return {any} A random member of the array.
*/
pick(ary) {
return ary[this.integerInRange(0, ary.length - 1)];
}
/**
* Returns a random member of `array`, favoring the earlier entries.
*
* @method RandomDataGenerator#weightedPick
* @param {Array} ary - An Array to pick a random member of.
* @return {any} A random member of the array.
*/
weightedPick(ary) {
return ary[~~(Math.pow(this.frac(), 2) * (ary.length - 1) + 0.5)];
}
/**
* Gets or Sets the state of the generator. This allows you to retain the values
* that the generator is using between games, i.e. in a game save file.
*
* To seed this generator with a previously saved state you can pass it as the
* `seed` value in your game config, or call this method directly after Phaser has booted.
*
* Call this method with no parameters to return the current state.
*
* If providing a state it should match the same format that this method
* returns, which is a string with a header `!rnd` followed by the `c`,
* `s0`, `s1` and `s2` values respectively, each comma-delimited.
*
* @method RandomDataGenerator#state
* @param {string} [state] - Generator state to be set.
* @return {string} The current state of the generator.
*/
state(state) {
if (typeof state === 'string' && state.match(/^!rnd/)) {
state = state.split(',');
this.c = parseFloat(state[1]);
this.s0 = parseFloat(state[2]);
this.s1 = parseFloat(state[3]);
this.s2 = parseFloat(state[4]);
}
return ['!rnd', this.c, this.s0, this.s1, this.s2].join(',');
}
}
/**
* An extremely useful repeatable random data generator.
*
* Based on RandomDataGenerator of Phaser engine, by Richard Davey <rich@photonstorm.com>
*
* The random number genererator is based on the Alea PRNG, but is modified.
* - https://github.com/coverslide/node-alea
* - https://github.com/nquinlan/better-random-numbers-for-javascript-mirror
* - http://baagoe.org/en/wiki/Better_random_numbers_for_javascript (original, perm. 404)
*
* @see RandomDataGenerator
*
* @exports engine/rnd
*/
module.exports = new RandomDataGenerator([(Date.now() * Math.random()).toString()]);
module.exports.RandomDataGenerator = RandomDataGenerator;