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JS: Remove Throwing Collection Checks (rFBOBJC)

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Reviewed By: sebmarkbage

Differential Revision: D2650824

fb-gh-sync-id: eb944a2086f1efff05215c9f6bd332d0a832606e
This commit is contained in:
Tim Yung 2015-11-12 19:35:13 -08:00 committed by facebook-github-bot-6
parent 5041171b78
commit c47116273d
1 changed files with 19 additions and 44 deletions
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63
Libraries/vendor/core/_shouldPolyfillES6Collection.js vendored
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@ -1,5 +1,5 @@
/**
* @generated SignedSource<<6c1a82d2f5918f03f3f0e5825e1f32f3>>
* @generated SignedSource<<bf0749e529897a7c9687fff37310d4d2>>
*
* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
* !! This file is a check-in of a static_upstream project! !!
@ -12,67 +12,42 @@
* !! static_upstream. !!
* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
*
* Copyright 2013-2014 Facebook, Inc.
* Copyright 2004-present Facebook. All Rights Reserved.
*
* @providesModule _shouldPolyfillES6Collection
* @preventMunge
* @typechecks
* @flow
*/
/**
* Given a collection class name (Map or Set) return whether it's safe to use
* the native polyfill.
*
* @param {string} collectionName
* Checks whether a collection name (e.g. "Map" or "Set") has a native polyfill
* that is safe to be used.
*/
function shouldPolyfillES6Collection(collectionName) {
function shouldPolyfillES6Collection(collectionName: string): boolean {
var Collection = global[collectionName];
if (Collection == null) {
return true;
}
// The iterator protocol depends on `Symbol.iterator`. If a collection is
// implemented, but `Symbol` is not, it's going to break iteration because
// we'll be using custom "@@iterator" instead, which is not implemented on
// native collections.
if (typeof global.Symbol !== 'function') {
return true;
}
var proto = Collection.prototype;
// These checks are adapted from es6-shim https://fburl.com/34437854
// These checks are adapted from es6-shim: https://fburl.com/34437854
// NOTE: `isCallableWithoutNew` and `!supportsSubclassing` are not checked
// because they make debugging with "break on exceptions" difficult.
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;
typeof proto.forEach !== 'function';
}
module.exports = shouldPolyfillES6Collection;