frequency-set/index.js

A set that keeps the frequency of occurrences.

// Require Internal Dependencies
const {
  isIterable, isValidStringPrimitive, isKeyValueArray
} = require("./src/utils.js");

class FrequencySet {
  #data = new Map();

  constructor(iterable = []) {
    if (iterable === null || iterable === undefined) {
      return;
    }
    if (!isIterable(iterable)) {
      throw new TypeError("object is not iterable (cannot read property Symbol(Symbol.iterator))");
    }

    for (const value of iterable) {
      if (isKeyValueArray(value)) {
        this.add(...value);
      }
      else {
        this.add(value);
      }
    }
  }

  add(value, count = 1) {
    if (typeof count !== "number") {
      throw new TypeError("count must be a number");
    }

    if (this.#data.has(value)) {
      this.#data.get(value).count += count;
    }
    else {
      this.#data.set(value, { count });
    }

    return this;
  }

  clear() {
    this.#data.clear();
  }

  delete(value) {
    return this.#data.delete(value);
  }

  * entries() {
    for (const [value, { count }] of this.#data.entries()) {
      yield [value, count];
    }
  }

  * [Symbol.iterator]() {
    yield* this.entries();
  }

  forEach(callback, thisArg) {
    for (const [value, count] of this.entries()) {
      callback.call(thisArg, value, count, this);
    }
  }

  has(value) {
    return this.#data.has(value);
  }

  values() {
    return this.#data.keys();
  }

  toJSON() {
    const payload = [];
    for (const [value, count] of this.entries()) {
      if (isValidStringPrimitive(value)) {
        payload.push([String(value), count]);
      }
    }

    return payload;
  }
}

module.exports = FrequencySet;