114 lines
4.0 KiB
JavaScript
114 lines
4.0 KiB
JavaScript
/**
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* Copyright (c) 2015-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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* @providesModule ReactNativeTagHandles
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* @flow
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*/
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'use strict';
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var invariant = require('invariant');
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var warning = require('warning');
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/**
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* Keeps track of allocating and associating native "tags" which are numeric,
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* unique view IDs. All the native tags are negative numbers, to avoid
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* collisions, but in the JS we keep track of them as positive integers to store
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* them effectively in Arrays. So we must refer to them as "inverses" of the
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* native tags (that are * normally negative).
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*
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* It *must* be the case that every `rootNodeID` always maps to the exact same
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* `tag` forever. The easiest way to accomplish this is to never delete
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* anything from this table.
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* Why: Because `dangerouslyReplaceNodeWithMarkupByID` relies on being able to
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* unmount a component with a `rootNodeID`, then mount a new one in its place,
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*/
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var INITIAL_TAG_COUNT = 1;
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var NATIVE_TOP_ROOT_ID_SEPARATOR = '{TOP_LEVEL}';
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var ReactNativeTagHandles = {
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tagsStartAt: INITIAL_TAG_COUNT,
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tagCount: INITIAL_TAG_COUNT,
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allocateTag: function(): number {
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// Skip over root IDs as those are reserved for native
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while (this.reactTagIsNativeTopRootID(ReactNativeTagHandles.tagCount)) {
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ReactNativeTagHandles.tagCount++;
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}
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var tag = ReactNativeTagHandles.tagCount;
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ReactNativeTagHandles.tagCount++;
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return tag;
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},
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/**
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* This associates the *last* observed *native* mounting between `rootNodeID`
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* and some `tag`. This association doesn't imply that `rootNodeID` is still
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* natively mounted as `tag`. The only reason why we don't clear the
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* association when the `rootNodeID` is unmounted, is that we don't have a
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* convenient time to disassociate them (otherwise we would).
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* `unmountComponent` isn't the correct time because that doesn't imply that
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* the native node has been natively unmounted.
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*/
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associateRootNodeIDWithMountedNodeHandle: function(
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rootNodeID: ?string,
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tag: ?number
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) {
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warning(rootNodeID && tag, 'Root node or tag is null when associating');
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if (rootNodeID && tag) {
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ReactNativeTagHandles.tagToRootNodeID[tag] = rootNodeID;
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ReactNativeTagHandles.rootNodeIDToTag[rootNodeID] = tag;
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}
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},
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allocateRootNodeIDForTag: function(tag: number): string {
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invariant(
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this.reactTagIsNativeTopRootID(tag),
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'Expect a native root tag, instead got ', tag
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);
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return '.r[' + tag + ']' + NATIVE_TOP_ROOT_ID_SEPARATOR;
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},
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reactTagIsNativeTopRootID: function(reactTag: number): bool {
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// We reserve all tags that are 1 mod 10 for native root views
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return reactTag % 10 === 1;
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},
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getNativeTopRootIDFromNodeID: function(nodeID: ?string): ?string {
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if (!nodeID) {
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return null;
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}
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var index = nodeID.indexOf(NATIVE_TOP_ROOT_ID_SEPARATOR);
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if (index === -1) {
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return null;
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}
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return nodeID.substr(0, index + NATIVE_TOP_ROOT_ID_SEPARATOR.length);
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},
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/**
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* Returns the native `nodeHandle` (`tag`) that was most recently *natively*
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* mounted at the `rootNodeID`. Just because a React component has been
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* mounted, that doesn't mean that its native node has been mounted. The
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* native node is mounted when we actually make the call to insert the
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* `nodeHandle` (`tag`) into the native hierarchy.
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*
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* @param {string} rootNodeID Root node ID to find most recently mounted tag
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* for. Again, this doesn't imply that it is still currently mounted.
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* @return {number} Tag ID of native view for most recent mounting of
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* `rootNodeID`.
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*/
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mostRecentMountedNodeHandleForRootNodeID: function(
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rootNodeID: string
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): number {
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return ReactNativeTagHandles.rootNodeIDToTag[rootNodeID];
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},
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tagToRootNodeID: ([] : Array<string>),
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rootNodeIDToTag: ({} : {[key: string]: number})
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};
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module.exports = ReactNativeTagHandles;
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