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package bjc.utils.funcutils;
import java.util.*;
import java.util.function.*;
/**
* A chain iterator. This is essentially flatMap in iterator form.
*
* @author bjculkin
*
* @param <T1>
* The type of the input values.
*
* @param <T2>
* The type of the output values.
*/
public class ChainIterator<T1, T2> implements Iterator<T2> {
private Iterator<T1> mainItr;
private Function<T1, Iterator<T2>> trans;
private Iterator<T2> curItr;
/**
* Create a new chain iterator.
*
* @param mainItr
* The main iterator for input.
*
* @param trans
* The transformation to use to produce the outputs.
*/
public ChainIterator(Iterator<T1> mainItr, Function<T1, Iterator<T2>> trans) {
this.mainItr = mainItr;
this.trans = trans;
}
@Override
public boolean hasNext() {
if (curItr != null) {
return curItr.hasNext() ? true : mainItr.hasNext();
}
return mainItr.hasNext();
}
@Override
public T2 next() {
if (curItr == null || !curItr.hasNext()) {
curItr = trans.apply(mainItr.next());
}
return curItr.next();
}
}
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