@mousepox/math/dist-es/Random.js

Math-related objects and utilities

const M = 0x80000000;
const A = 1103515245;
const C = 12345;
const DiceNotationPattern = /([0-9]+)?d([0-9]+)([+-]{1}[0-9]+)?/;
function parseDiceNotation(notation) {
    const matches = notation.match(DiceNotationPattern);
    if (matches === null) {
        throw new Error(`Invalid dice notation: ${notation}`);
    }
    return {
        bonus: Number(matches[3]),
        count: Number(matches[1]),
        sides: Number(matches[2]),
    };
}
export class Random {
    static getDiceNotationRange(notation) {
        const { count, sides, bonus } = parseDiceNotation(notation);
        return {
            max: count * sides + bonus,
            min: count * 1 + bonus,
        };
    }
    state = 0;
    constructor(seed) {
        this.reset(seed);
    }
    reset(seed) {
        if (seed !== undefined) {
            this.state = seed;
        }
        else {
            this.state = Math.floor(Math.random() * (M - 1));
        }
    }
    next() {
        this.state = (A * this.state + C) % M;
        return this.state / M;
    }
    integer(min, max) {
        return Math.floor(this.next() * (max - min + 1)) + min;
    }
    chance(probability) {
        return this.next() <= probability;
    }
    choice(items, remove = false) {
        const index = this.integer(0, items.length - 1);
        const pick = items[index];
        if (remove) {
            items.splice(index, 1);
        }
        return pick;
    }
    shuffle(items) {
        const len = items.length;
        if (len < 2) {
            return;
        }
        for (let i = 0; i < len; ++i) {
            const j = this.integer(i, len - 1);
            const swap = items[i];
            items[i] = items[j];
            items[j] = swap;
        }
    }
    rollDiceNotation(notation) {
        const { count, sides, bonus } = parseDiceNotation(notation);
        let result = bonus;
        for (let i = 0; i < count; ++i) {
            result += this.integer(1, sides);
        }
        return result;
    }
}