Files
react-native/Libraries/StyleSheet/splitLayoutProps.js
T
Tim Yung 54a067e61e RN: Refactor ScrollView Style Splitting
Summary:
Rewrites `splitLayoutProps`, which is only used by `ScrollView`.

- Improve type safety by avoiding `DangerouslyImpreciseStyle`.
- Avoid allocating objects when it is not necessary.
- Avoid allocating a object enumeratig layout props by using a switch statement.

Changelog:
[Internal]

Reviewed By: JoshuaGross, kacieb

Differential Revision: D25097226

fbshipit-source-id: 2050c03b681024212c06a48b7eb05f28c14415f9
2020-11-19 15:55:23 -08:00

69 lines
1.7 KiB
JavaScript

/**
* Copyright (c) Facebook, Inc. and its affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*
* @flow strict-local
* @format
*/
'use strict';
import type {____ViewStyle_Internal} from './StyleSheetTypes';
export default function splitLayoutProps(
props: ?____ViewStyle_Internal,
): {
outer: ?____ViewStyle_Internal,
inner: ?____ViewStyle_Internal,
} {
let outer: ?____ViewStyle_Internal = null;
let inner: ?____ViewStyle_Internal = null;
if (props != null) {
// $FlowIgnore[incompatible-exact] Will contain a subset of keys from `props`.
// $FlowIgnore[incompatible-type] Values are preserved within a key.
outer = {};
// $FlowIgnore[incompatible-exact] Will contain a subset of keys from `props`.
// $FlowIgnore[incompatible-type] Values are preserved within a key.
inner = {};
for (const prop of Object.keys(props)) {
switch (prop) {
case 'margin':
case 'marginHorizontal':
case 'marginVertical':
case 'marginBottom':
case 'marginTop':
case 'marginLeft':
case 'marginRight':
case 'flex':
case 'flexGrow':
case 'flexShrink':
case 'flexBasis':
case 'alignSelf':
case 'height':
case 'minHeight':
case 'maxHeight':
case 'width':
case 'minWidth':
case 'maxWidth':
case 'position':
case 'left':
case 'right':
case 'bottom':
case 'top':
case 'transform':
outer[prop] = props[prop];
break;
default:
inner[prop] = props[prop];
break;
}
}
}
return {outer, inner};
}