react-native/Libraries/ReactIOS/diffRawProperties.js

86 lines
3.1 KiB
JavaScript

/**
* Copyright 2004-present Facebook. All Rights Reserved.
*
* @providesModule diffRawProperties
*/
'use strict';
/**
* diffRawProperties takes two sets of props and a set of valid attributes
* and write to updatePayload the values that changed or were deleted
*
* @param {?object} updatePayload Overriden with the props that changed.
* @param {!object} prevProps Previous properties to diff against current
* properties. These properties are as supplied to component construction.
* @param {!object} prevProps Next "current" properties to diff against
* previous. These properties are as supplied to component construction.
* @return {?object}
*/
function diffRawProperties(updatePayload, prevProps, nextProps, validAttributes) {
var validAttributeConfig;
var nextProp;
var prevProp;
var isScalar;
var shouldUpdate;
for (var propKey in nextProps) {
validAttributeConfig = validAttributes[propKey];
if (!validAttributeConfig) {
continue; // not a valid native prop
}
prevProp = prevProps && prevProps[propKey];
nextProp = nextProps[propKey];
if (prevProp !== nextProp) {
// If you want a property's diff to be detected, you must configure it
// to be so - *or* it must be a scalar property. For now, we'll allow
// creation with any attribute that is not scalar, but we should
// eventually even reject those unless they are properly configured.
isScalar = typeof nextProp !== 'object' || nextProp === null;
shouldUpdate = isScalar ||
!prevProp ||
validAttributeConfig.diff &&
validAttributeConfig.diff(prevProp, nextProp);
if (shouldUpdate) {
updatePayload = updatePayload || {};
updatePayload[propKey] = nextProp;
}
}
}
// Also iterate through all the previous props to catch any that have been
// removed and make sure native gets the signal so it can reset them to the
// default.
for (var propKey in prevProps) {
validAttributeConfig = validAttributes[propKey];
if (!validAttributeConfig) {
continue; // not a valid native prop
}
if (updatePayload && updatePayload[propKey] !== undefined) {
continue; // Prop already specified
}
prevProp = prevProps[propKey];
nextProp = nextProps && nextProps[propKey];
if (prevProp !== nextProp) {
if (nextProp === undefined) {
nextProp = null; // null is a sentinel we explicitly send to native
}
// If you want a property's diff to be detected, you must configure it
// to be so - *or* it must be a scalar property. For now, we'll allow
// creation with any attribute that is not scalar, but we should
// eventually even reject those unless they are properly configured.
isScalar = typeof nextProp !== 'object' || nextProp === null;
shouldUpdate = isScalar && prevProp !== nextProp ||
validAttributeConfig.diff &&
validAttributeConfig.diff(prevProp, nextProp);
if (shouldUpdate) {
updatePayload = updatePayload || {};
updatePayload[propKey] = nextProp;
}
}
}
return updatePayload;
}
module.exports = diffRawProperties;