/**
* Copyright (c) 2015-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*/
package com.facebook.jni;
import com.facebook.proguard.annotations.DoNotStrip;
import javax.annotation.Nullable;
import java.util.Iterator;
/**
* To iterate over an Iterator from C++ requires two calls per entry: hasNext()
* and next(). This helper reduces it to one call and one field get per entry.
* It does not use a generic argument, since in C++, the types will be erased,
* anyway. This is *not* a {@link java.util.Iterator}.
*/
@DoNotStrip
public class IteratorHelper {
private final Iterator mIterator;
// This is private, but accessed via JNI.
@DoNotStrip
private @Nullable Object mElement;
@DoNotStrip
public IteratorHelper(Iterator iterator) {
mIterator = iterator;
}
@DoNotStrip
public IteratorHelper(Iterable iterable) {
mIterator = iterable.iterator();
}
/**
* Moves the helper to the next entry in the map, if any. Returns true iff
* there is an entry to read.
*/
@DoNotStrip
boolean hasNext() {
if (mIterator.hasNext()) {
mElement = mIterator.next();
return true;
} else {
mElement = null;
return false;
}
}
}