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| /**
* Copyright 2017 Google 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.
*/
import { NamedNode, Node } from '../snap/Node';
import { Change } from './Change';
import { assertionError } from '@firebase/util';
import { Query } from '../../api/Query';
import { Index } from '../snap/indexes/Index';
import { EventRegistration } from './EventRegistration';
import { Event } from './Event';
/**
* An EventGenerator is used to convert "raw" changes (Change) as computed by the
* CacheDiffer into actual events (Event) that can be raised. See generateEventsForChanges()
* for details.
*
* @constructor
*/
export class EventGenerator {
private index_: Index;
/**
*
* @param {!Query} query_
*/
constructor(private query_: Query) {
/**
* @private
* @type {!Index}
*/
this.index_ = this.query_.getQueryParams().getIndex();
}
/**
* Given a set of raw changes (no moved events and prevName not specified yet), and a set of
* EventRegistrations that should be notified of these changes, generate the actual events to be raised.
*
* Notes:
* - child_moved events will be synthesized at this time for any child_changed events that affect
* our index.
* - prevName will be calculated based on the index ordering.
*
* @param {!Array.<!Change>} changes
* @param {!Node} eventCache
* @param {!Array.<!EventRegistration>} eventRegistrations
* @return {!Array.<!Event>}
*/
generateEventsForChanges(
changes: Change[],
eventCache: Node,
eventRegistrations: EventRegistration[]
): Event[] {
const events: Event[] = [];
const moves: Change[] = [];
changes.forEach(change => {
if (
change.type === Change.CHILD_CHANGED &&
this.index_.indexedValueChanged(
change.oldSnap as Node,
change.snapshotNode
)
) {
moves.push(
Change.childMovedChange(
change.childName as string,
change.snapshotNode
)
);
}
});
this.generateEventsForType_(
events,
Change.CHILD_REMOVED,
changes,
eventRegistrations,
eventCache
);
this.generateEventsForType_(
events,
Change.CHILD_ADDED,
changes,
eventRegistrations,
eventCache
);
this.generateEventsForType_(
events,
Change.CHILD_MOVED,
moves,
eventRegistrations,
eventCache
);
this.generateEventsForType_(
events,
Change.CHILD_CHANGED,
changes,
eventRegistrations,
eventCache
);
this.generateEventsForType_(
events,
Change.VALUE,
changes,
eventRegistrations,
eventCache
);
return events;
}
/**
* Given changes of a single change type, generate the corresponding events.
*
* @param {!Array.<!Event>} events
* @param {!string} eventType
* @param {!Array.<!Change>} changes
* @param {!Array.<!EventRegistration>} registrations
* @param {!Node} eventCache
* @private
*/
private generateEventsForType_(
events: Event[],
eventType: string,
changes: Change[],
registrations: EventRegistration[],
eventCache: Node
) {
const filteredChanges = changes.filter(change => change.type === eventType);
filteredChanges.sort(this.compareChanges_.bind(this));
filteredChanges.forEach(change => {
const materializedChange = this.materializeSingleChange_(
change,
eventCache
);
registrations.forEach(registration => {
if (registration.respondsTo(change.type)) {
events.push(
registration.createEvent(materializedChange, this.query_)
);
}
});
});
}
/**
* @param {!Change} change
* @param {!Node} eventCache
* @return {!Change}
* @private
*/
private materializeSingleChange_(change: Change, eventCache: Node): Change {
if (change.type === 'value' || change.type === 'child_removed') {
return change;
} else {
change.prevName = eventCache.getPredecessorChildName(
/** @type {!string} */
change.childName,
change.snapshotNode,
this.index_
);
return change;
}
}
/**
* @param {!Change} a
* @param {!Change} b
* @return {number}
* @private
*/
private compareChanges_(a: Change, b: Change) {
Iif (a.childName == null || b.childName == null) {
throw assertionError('Should only compare child_ events.');
}
const aWrapped = new NamedNode(a.childName, a.snapshotNode);
const bWrapped = new NamedNode(b.childName, b.snapshotNode);
return this.index_.compare(aWrapped, bWrapped);
}
}
|