source: imaps-frontend/node_modules/es-abstract/2018/WordCharacters.js

'use strict';

var $TypeError = require('es-errors/type');

var callBound = require('call-bind/callBound');
var $indexOf = callBound('String.prototype.indexOf', true);

var Canonicalize = require('./Canonicalize');

var caseFolding = require('../helpers/caseFolding.json');
var forEach = require('../helpers/forEach');
var OwnPropertyKeys = require('../helpers/OwnPropertyKeys');

var A = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_'; // step 1

// https://262.ecma-international.org/8.0/#sec-runtime-semantics-wordcharacters-abstract-operation

module.exports = function WordCharacters(IgnoreCase, Unicode) {
        if (typeof IgnoreCase !== 'boolean' || typeof Unicode !== 'boolean') {
                throw new $TypeError('Assertion failed: `IgnoreCase` and `Unicode` must be booleans');
        }

        var U = '';
        forEach(OwnPropertyKeys(caseFolding.C), function (c) {
                if (
                        $indexOf(A, c) === -1 // c not in A
                        && $indexOf(A, Canonicalize(c, IgnoreCase, Unicode)) > -1 // canonicalized c IS in A
                ) {
                        U += caseFolding.C[c]; // step 3
                }
        });
        forEach(OwnPropertyKeys(caseFolding.S), function (c) {
                if (
                        $indexOf(A, c) === -1 // c not in A
                        && $indexOf(A, Canonicalize(c, IgnoreCase, Unicode)) > -1 // canonicalized c IS in A
                ) {
                        U += caseFolding.S[c]; // step 3
                }
        });

        if ((!Unicode || !IgnoreCase) && U.length > 0) {
                throw new $TypeError('Assertion failed: `U` must be empty when `IgnoreCase` and `Unicode` are not both true'); // step 4
        }

        return A + U; // step 5, 6
};