react-native/Libraries/vendor/react/event/EventPropagators.js

164 lines
5.4 KiB
JavaScript

/**
* Copyright 2013-2014 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* @providesModule EventPropagators
*/
"use strict";
var EventConstants = require('EventConstants');
var EventPluginHub = require('EventPluginHub');
var accumulateInto = require('accumulateInto');
var forEachAccumulated = require('forEachAccumulated');
var PropagationPhases = EventConstants.PropagationPhases;
var getListener = EventPluginHub.getListener;
/**
* Some event types have a notion of different registration names for different
* "phases" of propagation. This finds listeners by a given phase.
*/
function listenerAtPhase(id, event, propagationPhase) {
var registrationName =
event.dispatchConfig.phasedRegistrationNames[propagationPhase];
return getListener(id, registrationName);
}
/**
* Tags a `SyntheticEvent` with dispatched listeners. Creating this function
* here, allows us to not have to bind or create functions for each event.
* Mutating the event's members allows us to not have to create a wrapping
* "dispatch" object that pairs the event with the listener.
*/
function accumulateDirectionalDispatches(domID, upwards, event) {
if (__DEV__) {
if (!domID) {
throw new Error('Dispatching id must not be null');
}
}
var phase = upwards ? PropagationPhases.bubbled : PropagationPhases.captured;
var listener = listenerAtPhase(domID, event, phase);
if (listener) {
event._dispatchListeners =
accumulateInto(event._dispatchListeners, listener);
event._dispatchIDs = accumulateInto(event._dispatchIDs, domID);
}
}
/**
* Collect dispatches (must be entirely collected before dispatching - see unit
* tests). Lazily allocate the array to conserve memory. We must loop through
* each event and perform the traversal for each one. We can not perform a
* single traversal for the entire collection of events because each event may
* have a different target.
*/
function accumulateTwoPhaseDispatchesSingle(event) {
if (event && event.dispatchConfig.phasedRegistrationNames) {
EventPluginHub.injection.getInstanceHandle().traverseTwoPhase(
event.dispatchMarker,
accumulateDirectionalDispatches,
event
);
}
}
/**
* Same as `accumulateTwoPhaseDispatchesSingle`, but skips over the targetID.
*/
function accumulateTwoPhaseDispatchesSingleSkipTarget(event) {
if (event && event.dispatchConfig.phasedRegistrationNames) {
EventPluginHub.injection.getInstanceHandle().traverseTwoPhaseSkipTarget(
event.dispatchMarker,
accumulateDirectionalDispatches,
event
);
}
}
/**
* Accumulates without regard to direction, does not look for phased
* registration names. Same as `accumulateDirectDispatchesSingle` but without
* requiring that the `dispatchMarker` be the same as the dispatched ID.
*/
function accumulateDispatches(id, ignoredDirection, event) {
if (event && event.dispatchConfig.registrationName) {
var registrationName = event.dispatchConfig.registrationName;
var listener = getListener(id, registrationName);
if (listener) {
event._dispatchListeners =
accumulateInto(event._dispatchListeners, listener);
event._dispatchIDs = accumulateInto(event._dispatchIDs, id);
}
}
}
/**
* Accumulates dispatches on an `SyntheticEvent`, but only for the
* `dispatchMarker`.
* @param {SyntheticEvent} event
*/
function accumulateDirectDispatchesSingle(event) {
if (event && event.dispatchConfig.registrationName) {
accumulateDispatches(event.dispatchMarker, null, event);
}
}
function accumulateTwoPhaseDispatches(events) {
forEachAccumulated(events, accumulateTwoPhaseDispatchesSingle);
}
function accumulateTwoPhaseDispatchesSkipTarget(events) {
forEachAccumulated(events, accumulateTwoPhaseDispatchesSingleSkipTarget);
}
function accumulateEnterLeaveDispatches(leave, enter, fromID, toID) {
EventPluginHub.injection.getInstanceHandle().traverseEnterLeave(
fromID,
toID,
accumulateDispatches,
leave,
enter
);
}
function accumulateDirectDispatches(events) {
forEachAccumulated(events, accumulateDirectDispatchesSingle);
}
/**
* A small set of propagation patterns, each of which will accept a small amount
* of information, and generate a set of "dispatch ready event objects" - which
* are sets of events that have already been annotated with a set of dispatched
* listener functions/ids. The API is designed this way to discourage these
* propagation strategies from actually executing the dispatches, since we
* always want to collect the entire set of dispatches before executing event a
* single one.
*
* @constructor EventPropagators
*/
var EventPropagators = {
accumulateTwoPhaseDispatches: accumulateTwoPhaseDispatches,
accumulateTwoPhaseDispatchesSkipTarget: accumulateTwoPhaseDispatchesSkipTarget,
accumulateDirectDispatches: accumulateDirectDispatches,
accumulateEnterLeaveDispatches: accumulateEnterLeaveDispatches
};
module.exports = EventPropagators;