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"use strict";
Object.defineProperty(exports, "__esModule", {
value: true
});
exports.default = safeArrayFrom;
var _symbols = require("../polyfills/symbols.js");
function _typeof(obj) { "@babel/helpers - typeof"; if (typeof Symbol === "function" && typeof Symbol.iterator === "symbol") { _typeof = function _typeof(obj) { return typeof obj; }; } else { _typeof = function _typeof(obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; }; } return _typeof(obj); }
/**
* Safer version of `Array.from` that return `null` if value isn't convertible to array.
* Also protects against Array-like objects without items.
*
* @example
*
* safeArrayFrom([ 1, 2, 3 ]) // [1, 2, 3]
* safeArrayFrom('ABC') // null
* safeArrayFrom({ length: 1 }) // null
* safeArrayFrom({ length: 1, 0: 'Alpha' }) // ['Alpha']
* safeArrayFrom({ key: 'value' }) // null
* safeArrayFrom(new Map()) // []
*
*/
function safeArrayFrom(collection) {
var mapFn = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : function (item) {
return item;
};
if (collection == null || _typeof(collection) !== 'object') {
return null;
}
if (Array.isArray(collection)) {
return collection.map(mapFn);
} // Is Iterable?
var iteratorMethod = collection[_symbols.SYMBOL_ITERATOR];
if (typeof iteratorMethod === 'function') {
// $FlowFixMe[incompatible-use]
var iterator = iteratorMethod.call(collection);
var result = [];
var step;
for (var i = 0; !(step = iterator.next()).done; ++i) {
result.push(mapFn(step.value, i));
}
return result;
} // Is Array like?
var length = collection.length;
if (typeof length === 'number' && length >= 0 && length % 1 === 0) {
var _result = [];
for (var _i = 0; _i < length; ++_i) {
if (!Object.prototype.hasOwnProperty.call(collection, _i)) {
return null;
}
_result.push(mapFn(collection[String(_i)], _i));
}
return _result;
}
return null;
}
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