refactor (#24)

* refactor helpers

* refactor tests

* refactor Grammar

* change size

.eslintrc.json

@@ -1,12 +1,10 @@
 {
   "extends": "airbnb-base",
-  "globals": {
-    "define": true
-  },
   "rules": {
     "array-callback-return": "off",
     "consistent-return": "off",
+    "no-loop-func": "off",
     "no-underscore-dangle": "off",
-    "no-loop-func": "off"
+    "object-curly-newline": "off"
   }
 }

README.md

@@ -4,7 +4,7 @@
 [![GitHub release](https://img.shields.io/github/release/MikeDevice/first-follow.svg)](https://github.com/MikeDevice/first-follow/releases)
 [![Coverage Status](https://coveralls.io/repos/github/MikeDevice/first-follow/badge.svg?branch=master)](https://coveralls.io/github/MikeDevice/first-follow?branch=master)
 
-A small tool for calculating first, follow and predict sets for a grammar. Its size is only 804 bytes (minified and gzipped). No dependencies. [Size Limit](https://github.com/ai/size-limit) controls the size.
+A small tool for calculating first, follow and predict sets for a grammar. Its size is only 697 bytes (minified and gzipped). No dependencies. [Size Limit](https://github.com/ai/size-limit) controls the size.
 
 
 ## Installation

lib/helpers.js

@@ -1,29 +1,14 @@
-const { EMPTY_CHAIN } = require('./constants');
+exports.uniq = (arr) => arr.filter((item, index) => arr.indexOf(item) === index);
 
-exports.addToSet = (dest, src, { skipEmptyChain } = {}) => new Set([
-  ...dest,
-  ...skipEmptyChain
-    ? [...src].filter((item) => item !== EMPTY_CHAIN)
-    : src,
-]);
+exports.union = (arr1, arr2) => exports.uniq(arr1.concat(arr2));
 
-exports.mapSetsToArrays = (sets) => {
-  const result = {};
-
-  Object.keys(sets).map((key) => {
-    result[key] = [...sets[key]];
-  });
-
-  return result;
-};
+exports.compact = (arr) => arr.filter(Boolean);
 
-exports.indexBy = (arr, func) => {
-  const iteratee = func || ((a) => a);
+exports.indexBy = (arr) => {
   const result = {};
 
-  arr.forEach((item, index) => {
-    const key = iteratee(item, index);
-    result[key] = item;
+  arr.forEach((item) => {
+    result[item] = item;
   });
 
   return result;