79 lines
2.2 KiB
JavaScript
79 lines
2.2 KiB
JavaScript
/**
|
|
* @generated SignedSource<<6c1a82d2f5918f03f3f0e5825e1f32f3>>
|
|
*
|
|
* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
|
|
* !! This file is a check-in of a static_upstream project! !!
|
|
* !! !!
|
|
* !! You should not modify this file directly. Instead: !!
|
|
* !! 1) Use `fjs use-upstream` to temporarily replace this with !!
|
|
* !! the latest version from upstream. !!
|
|
* !! 2) Make your changes, test them, etc. !!
|
|
* !! 3) Use `fjs push-upstream` to copy your changes back to !!
|
|
* !! static_upstream. !!
|
|
* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
|
|
*
|
|
* Copyright 2013-2014 Facebook, Inc.
|
|
* @providesModule _shouldPolyfillES6Collection
|
|
* @preventMunge
|
|
* @typechecks
|
|
*/
|
|
|
|
/**
|
|
* Given a collection class name (Map or Set) return whether it's safe to use
|
|
* the native polyfill.
|
|
*
|
|
* @param {string} collectionName
|
|
*/
|
|
function shouldPolyfillES6Collection(collectionName) {
|
|
var Collection = global[collectionName];
|
|
if (Collection == null) {
|
|
return true;
|
|
}
|
|
|
|
var proto = Collection.prototype;
|
|
|
|
// These checks are adapted from es6-shim https://fburl.com/34437854
|
|
return Collection == null ||
|
|
typeof Collection !== 'function' ||
|
|
typeof proto.clear !== 'function' ||
|
|
new Collection().size !== 0 ||
|
|
typeof proto.keys !== 'function' ||
|
|
typeof proto.forEach !== 'function' ||
|
|
isCallableWithoutNew(Collection) ||
|
|
!supportsSubclassing(Collection);
|
|
}
|
|
|
|
/**
|
|
* Given a class can we subclass it?
|
|
*
|
|
* @param {function} Collection
|
|
*/
|
|
function supportsSubclassing(Collection) {
|
|
class SubCollection extends Collection {}
|
|
try {
|
|
var s = (new SubCollection([]));
|
|
// Firefox 32 will throw a type error when any operation is called on a
|
|
// subclass.
|
|
s.size;
|
|
return s instanceof Collection;
|
|
} catch (e) {
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Given a constructor can we call it without `new`?
|
|
*
|
|
* @param {function} Collection
|
|
*/
|
|
function isCallableWithoutNew(Collection) {
|
|
try {
|
|
Collection();
|
|
} catch (e) {
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
module.exports = shouldPolyfillES6Collection;
|