102 lines
3.2 KiB
JavaScript
102 lines
3.2 KiB
JavaScript
/**
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* Copyright 2013-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*
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*/
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'use strict';
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var flattenChildren = require('./flattenChildren');
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var ReactTransitionChildMapping = {
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/**
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* Given `this.props.children`, return an object mapping key to child. Just
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* simple syntactic sugar around flattenChildren().
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*
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* @param {*} children `this.props.children`
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* @param {number=} selfDebugID Optional debugID of the current internal instance.
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* @return {object} Mapping of key to child
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*/
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getChildMapping: function (children, selfDebugID) {
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if (!children) {
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return children;
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}
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if (process.env.NODE_ENV !== 'production') {
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return flattenChildren(children, selfDebugID);
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}
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return flattenChildren(children);
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},
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/**
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* When you're adding or removing children some may be added or removed in the
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* same render pass. We want to show *both* since we want to simultaneously
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* animate elements in and out. This function takes a previous set of keys
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* and a new set of keys and merges them with its best guess of the correct
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* ordering. In the future we may expose some of the utilities in
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* ReactMultiChild to make this easy, but for now React itself does not
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* directly have this concept of the union of prevChildren and nextChildren
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* so we implement it here.
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*
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* @param {object} prev prev children as returned from
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* `ReactTransitionChildMapping.getChildMapping()`.
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* @param {object} next next children as returned from
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* `ReactTransitionChildMapping.getChildMapping()`.
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* @return {object} a key set that contains all keys in `prev` and all keys
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* in `next` in a reasonable order.
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*/
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mergeChildMappings: function (prev, next) {
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prev = prev || {};
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next = next || {};
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function getValueForKey(key) {
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if (next.hasOwnProperty(key)) {
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return next[key];
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} else {
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return prev[key];
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}
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}
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// For each key of `next`, the list of keys to insert before that key in
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// the combined list
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var nextKeysPending = {};
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var pendingKeys = [];
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for (var prevKey in prev) {
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if (next.hasOwnProperty(prevKey)) {
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if (pendingKeys.length) {
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nextKeysPending[prevKey] = pendingKeys;
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pendingKeys = [];
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}
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} else {
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pendingKeys.push(prevKey);
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}
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}
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var i;
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var childMapping = {};
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for (var nextKey in next) {
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if (nextKeysPending.hasOwnProperty(nextKey)) {
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for (i = 0; i < nextKeysPending[nextKey].length; i++) {
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var pendingNextKey = nextKeysPending[nextKey][i];
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childMapping[nextKeysPending[nextKey][i]] = getValueForKey(pendingNextKey);
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}
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}
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childMapping[nextKey] = getValueForKey(nextKey);
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}
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// Finally, add the keys which didn't appear before any key in `next`
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for (i = 0; i < pendingKeys.length; i++) {
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childMapping[pendingKeys[i]] = getValueForKey(pendingKeys[i]);
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}
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return childMapping;
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}
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};
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module.exports = ReactTransitionChildMapping; |