77 lines
2.5 KiB
Java
77 lines
2.5 KiB
Java
package androidx.lifecycle;
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import androidx.annotation.CallSuper;
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import androidx.annotation.MainThread;
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import androidx.annotation.NonNull;
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import androidx.annotation.Nullable;
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import androidx.arch.core.internal.SafeIterableMap;
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import java.util.Iterator;
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import java.util.Map;
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public class MediatorLiveData<T> extends MutableLiveData<T> {
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private SafeIterableMap<LiveData<?>, Source<?>> mSources = new SafeIterableMap<>();
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public static class Source<V> implements Observer<V> {
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public final LiveData<V> mLiveData;
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public final Observer<? super V> mObserver;
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public int mVersion = -1;
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public Source(LiveData<V> liveData, Observer<? super V> observer) {
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this.mLiveData = liveData;
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this.mObserver = observer;
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}
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@Override // androidx.lifecycle.Observer
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public void onChanged(@Nullable V v) {
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if (this.mVersion != this.mLiveData.getVersion()) {
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this.mVersion = this.mLiveData.getVersion();
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this.mObserver.onChanged(v);
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}
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}
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public void plug() {
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this.mLiveData.observeForever(this);
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}
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public void unplug() {
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this.mLiveData.removeObserver(this);
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}
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}
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@MainThread
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public <S> void addSource(@NonNull LiveData<S> liveData, @NonNull Observer<? super S> observer) {
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Source<?> source = new Source<>(liveData, observer);
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Source<?> putIfAbsent = this.mSources.putIfAbsent(liveData, source);
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if (putIfAbsent != null && putIfAbsent.mObserver != observer) {
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throw new IllegalArgumentException("This source was already added with the different observer");
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} else if (putIfAbsent == null && hasActiveObservers()) {
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source.plug();
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}
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}
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@Override // androidx.lifecycle.LiveData
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@CallSuper
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public void onActive() {
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Iterator<Map.Entry<LiveData<?>, Source<?>>> it = this.mSources.iterator();
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while (it.hasNext()) {
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it.next().getValue().plug();
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}
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}
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@Override // androidx.lifecycle.LiveData
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@CallSuper
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public void onInactive() {
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Iterator<Map.Entry<LiveData<?>, Source<?>>> it = this.mSources.iterator();
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while (it.hasNext()) {
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it.next().getValue().unplug();
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}
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}
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@MainThread
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public <S> void removeSource(@NonNull LiveData<S> liveData) {
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Source<?> remove = this.mSources.remove(liveData);
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if (remove != null) {
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remove.unplug();
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}
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}
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}
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