DynamicTypeValueReceiverWithPreUpdate.java
/*
* Copyright 2022 The Android Open Source Project
*
* 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.
*/
package androidx.wear.protolayout.expression.pipeline;
/**
* @see DynamicTypeValueReceiver
* <p>It is guaranteed that for any given batch evaluation result, {@link #onPreUpdate()} will
* be called on all listeners before any {@link #onData} or {@link #onInvalidated} calls are
* fired.
* @param <T> Data type.
*/
interface DynamicTypeValueReceiverWithPreUpdate<T>
extends DynamicTypeValueReceiver<T> {
/**
* Called when evaluation result for the dynamic type that this callback was registered for is
* about to be updated. This allows a downstream consumer to properly synchronize updates if it
* depends on two or more evaluation result items. In that case, it should use this call to
* figure out how many of its dependencies are going to be updated, and wait for all of them to
* be updated (via {@link #onData(T)}) or {@link #onInvalidated()} before acting on the change.
*/
void onPreUpdate();
}