59 lines
1.7 KiB
Java
59 lines
1.7 KiB
Java
/**
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* Copyright 2018-present, Facebook, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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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 javax.annotation.Nullable;
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/**
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* To iterate over an Iterator from C++ requires two calls per entry: hasNext() and next(). This
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* helper reduces it to one call and one field get per entry. It does not use a generic argument,
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* since in C++, the types will be erased, anyway. This is *not* a {@link java.util.Iterator}.
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*/
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@DoNotStrip
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public class IteratorHelper {
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private final Iterator mIterator;
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// This is private, but accessed via JNI.
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@DoNotStrip private @Nullable Object mElement;
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@DoNotStrip
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public IteratorHelper(Iterator iterator) {
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mIterator = iterator;
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}
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@DoNotStrip
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public IteratorHelper(Iterable iterable) {
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mIterator = iterable.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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mElement = mIterator.next();
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return true;
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} else {
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mElement = null;
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return false;
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}
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}
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}
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