source: imaps-frontend/node_modules/is-regex/index.js

'use strict';

var callBound = require('call-bind/callBound');
var hasToStringTag = require('has-tostringtag/shams')();
var has;
var $exec;
var isRegexMarker;
var badStringifier;

if (hasToStringTag) {
        has = callBound('Object.prototype.hasOwnProperty');
        $exec = callBound('RegExp.prototype.exec');
        isRegexMarker = {};

        var throwRegexMarker = function () {
                throw isRegexMarker;
        };
        badStringifier = {
                toString: throwRegexMarker,
                valueOf: throwRegexMarker
        };

        if (typeof Symbol.toPrimitive === 'symbol') {
                badStringifier[Symbol.toPrimitive] = throwRegexMarker;
        }
}

var $toString = callBound('Object.prototype.toString');
var gOPD = Object.getOwnPropertyDescriptor;
var regexClass = '[object RegExp]';

module.exports = hasToStringTag
        // eslint-disable-next-line consistent-return
        ? function isRegex(value) {
                if (!value || typeof value !== 'object') {
                        return false;
                }

                var descriptor = gOPD(value, 'lastIndex');
                var hasLastIndexDataProperty = descriptor && has(descriptor, 'value');
                if (!hasLastIndexDataProperty) {
                        return false;
                }

                try {
                        $exec(value, badStringifier);
                } catch (e) {
                        return e === isRegexMarker;
                }
        }
        : function isRegex(value) {
                // In older browsers, typeof regex incorrectly returns 'function'
                if (!value || (typeof value !== 'object' && typeof value !== 'function')) {
                        return false;
                }

                return $toString(value) === regexClass;
        };