@gent-js/gent/dist/src/common/weightedItemFeeder.js

template-based data generator.

import { faker } from "@faker-js/faker";
const DEFAULT_WEIGHT = 1;
const MIN_WEIGHT = 0;
const MAX_WEIGHT = 2 ** 16;
export class WeightedItemFeeder {
    totalWeight = -1;
    normalizedWeightedItems;
    constructor(...weightedItems) {
        this.normalizedWeightedItems = weightedItems.map(normalizeWeightedItem);
        this.updateTotalWeight();
    }
    get size() {
        return this.normalizedWeightedItems.length;
    }
    addItem(item, weight = DEFAULT_WEIGHT) {
        const weightedItem = {
            content: item,
            weight: weight,
        };
        this.addWeightedItem(weightedItem);
    }
    addWeightedItem(weightedItem) {
        this.normalizedWeightedItems.push(normalizeWeightedItem(weightedItem));
        this.updateTotalWeight();
    }
    getItem() {
        const totalWeight = this.totalWeight;
        if (totalWeight < MIN_WEIGHT) {
            return undefined;
        }
        const targetAccumWeight = faker.number.float({
            min: MIN_WEIGHT,
            max: totalWeight,
        });
        let accumWeight = MIN_WEIGHT;
        const weightedItem = this.normalizedWeightedItems.find(({ weight }) => {
            accumWeight = accumWeight + weight;
            if (targetAccumWeight <= accumWeight) {
                return true;
            }
            return false;
        });
        return weightedItem?.content;
    }
    updateTotalWeight() {
        this.totalWeight = this.normalizedWeightedItems.reduce((sum, { weight }) => {
            return sum + weight;
        }, 0);
    }
}
function normalizeWeightedItem(weightedItem) {
    let weight;
    if (typeof weightedItem.weight === "number") {
        weight = weightedItem.weight;
    }
    else {
        weight = DEFAULT_WEIGHT;
    }
    return {
        content: weightedItem.content,
        weight: normalizeWeight(weight),
    };
}
export function normalizeWeight(value) {
    return Math.min(Math.max(value, MIN_WEIGHT), MAX_WEIGHT);
}