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package dev.marksman.collectionviews;
import java.util.Iterator;
import java.util.Objects;
/**
* Helper methods for implementers of custom {@link Vector}s.
*
* If you are implementing a custom {@link Vector}, your {@code equals} and {@code hashCode}
* methods SHOULD delegate to {@code vectorEquals} and {@code vectorHashCode}, respectively. This will
* ensure that equality works correctly with the built-in {@link Vector} types.
*
* Your {@code toString} method MAY delegate to {@code vectorToString}.
*/
@SuppressWarnings("WeakerAccess")
public final class VectorHelpers {
private VectorHelpers() {
}
public static boolean vectorEquals(Vector vector, Vector other) {
if (vector == null || other == null) {
return false;
}
if (other == vector) {
return true;
} else {
return (other.size() == vector.size())
&& allElementsEqual(vector.iterator(), other.iterator());
}
}
public static int vectorHashCode(Vector vector) {
int hashCode = 1;
for (Object e : vector) {
hashCode = 31 * hashCode + (e == null ? 0 : e.hashCode());
}
return hashCode;
}
public static Iterator vectorIterator(Vector vector) {
return new VectorIterator<>(vector);
}
public static String vectorToString(Vector vector) {
return Util.iterableToString("Vector", vector);
}
private static boolean allElementsEqual(Iterator e1, Iterator e2) {
while (e1.hasNext() && e2.hasNext()) {
Object o1 = e1.next();
Object o2 = e2.next();
if (!(Objects.equals(o1, o2))) {
return false;
}
}
return !(e1.hasNext() || e2.hasNext());
}
}