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package org.eclipse.viatra.solver.data.util;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.function.Function;
import java.util.function.Predicate;
public final class CollectionsUtil {
private CollectionsUtil() {
throw new UnsupportedOperationException();
}
public static <S,T> Iterator<T> map(Iterator<S> source, Function<S, T> transformation) {
return new Iterator<T>() {
@Override
public boolean hasNext() {
return source.hasNext();
}
@Override
public T next() {
return transformation.apply(source.next());
}
};
}
public static <S,T> Iterable<T> map(Iterable<S> source, Function<S, T> transformation) {
return (()->map(source.iterator(),transformation));
}
public static <T> Iterator<T> filter(Iterator<T> source, Predicate<T> condition) {
return new Iterator<T>() {
T internalNext = move();
boolean internalHasNext;
private T move() {
internalHasNext = source.hasNext();
if(internalHasNext) {
internalNext = source.next();
}
while(internalHasNext && !condition.test(internalNext)) {
internalHasNext = source.hasNext();
if(internalHasNext) {
internalNext = source.next();
}
}
return internalNext;
}
@Override
public boolean hasNext() {
return internalHasNext;
}
@Override
public T next() {
if(!internalHasNext) {
throw new NoSuchElementException();
} else {
T result = internalNext;
move();
return result;
}
}
};
}
public static <T> Iterable<T> filter(Iterable<T> source, Predicate<T> condition) {
return (()->filter(source.iterator(),condition));
}
}
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