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Copy pathIxScanSeed.java
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76 lines (59 loc) · 1.97 KB
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/*
* Copyright 2011-2016 David Karnok
*
* 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 ix;
import java.util.Iterator;
final class IxScanSeed<T, R> extends IxSource<T, R> {
final IxSupplier<R> seed;
final IxFunction2<R, T, R> scanner;
IxScanSeed(Iterable<T> source, IxSupplier<R> seed, IxFunction2<R, T, R> scanner) {
super(source);
this.seed = seed;
this.scanner = scanner;
}
@Override
public Iterator<R> iterator() {
return new ScanSeedIterator<T, R>(source.iterator(), seed.get(), scanner);
}
static final class ScanSeedIterator<T, R> extends IxSourceIterator<T, R> {
final IxFunction2<R, T, R> scanner;
R accumulator;
boolean once;
ScanSeedIterator(Iterator<T> it, R accumulator, IxFunction2<R, T, R> scanner) {
super(it);
this.accumulator = accumulator;
this.scanner = scanner;
}
@Override
protected boolean moveNext() {
if (!once) {
once = true;
value = accumulator;
hasValue = true;
return true;
}
if (it.hasNext()) {
R v = scanner.apply(accumulator, it.next());
accumulator = v;
value = v;
hasValue = true;
return true;
}
accumulator = null;
done = true;
return false;
}
}
}