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package bjc.utils.esodata;
import java.util.Deque;
import java.util.LinkedList;
/**
* A FIFO implementation of a stack.
*
* @param <T>
* The datatype stored in the stack.
* @author Ben Culkin
*/
public class QueueStack<T> extends Stack<T> {
private Deque<T> backing;
/**
* Create a new empty stack queue.
*
*/
public QueueStack() {
backing = new LinkedList<>();
}
@Override
public void push(T elm) {
backing.add(elm);
}
@Override
public T pop() {
if (backing.isEmpty())
throw new StackUnderflowException();
return backing.remove();
}
@Override
public T top() {
if (backing.isEmpty())
throw new StackUnderflowException();
return backing.peek();
}
@Override
public int size() {
return backing.size();
}
@Override
public boolean empty() {
return backing.size() == 0;
}
@SuppressWarnings("unchecked")
@Override
public T[] toArray() {
return (T[]) backing.toArray();
}
@Override
public String toString() {
return String.format("QueueStack [backing=%s]", backing);
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((backing == null) ? 0 : backing.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (!(obj instanceof QueueStack<?>))
return false;
QueueStack<?> other = (QueueStack<?>) obj;
if (backing == null) {
if (other.backing != null)
return false;
} else if (!backing.equals(other.backing))
return false;
return true;
}
}
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