50 lines
1.3 KiB
Java
50 lines
1.3 KiB
Java
/*
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* Copyright (c) 2018-present, Facebook, Inc.
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*
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* This source code is licensed under the MIT license found in the LICENSE
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* file in the root directory of this source tree.
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*
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*/
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package com.facebook.jni;
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import com.facebook.jni.annotations.DoNotStrip;
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import java.util.Iterator;
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import java.util.Map;
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import javax.annotation.Nullable;
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/**
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* To iterate over a Map from C++ requires four calls per entry: hasNext(), next(), getKey(),
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* getValue(). This helper reduces it to one call and two field gets per entry. It does not use a
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* generic argument, since in C++, the types will be erased, anyway. This is *not* a {@link
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* java.util.Iterator}.
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*/
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@DoNotStrip
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public class MapIteratorHelper {
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@DoNotStrip private final Iterator<Map.Entry> mIterator;
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@DoNotStrip private @Nullable Object mKey;
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@DoNotStrip private @Nullable Object mValue;
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@DoNotStrip
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public MapIteratorHelper(Map map) {
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mIterator = map.entrySet().iterator();
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}
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/**
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* Moves the helper to the next entry in the map, if any. Returns true iff there is an entry to
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* read.
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*/
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@DoNotStrip
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boolean hasNext() {
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if (mIterator.hasNext()) {
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Map.Entry entry = mIterator.next();
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mKey = entry.getKey();
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mValue = entry.getValue();
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return true;
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} else {
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mKey = null;
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mValue = null;
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return false;
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}
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}
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}
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