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package bjc.esodata;
import java.util.Arrays;
import java.util.stream.Stream;
/**
* Implements a spaghetti stack, which is a stack that is branched off of a
* parent stack.
*
* @param <T>
* The datatype stored in the stack.
*
* @author Ben Culkin
*/
class SpaghettiStack<T> extends Stack<T> {
/* Our backing stack. */
private final Stack<T> backing;
/* The stack we branched off of. */
private final Stack<T> parent;
/**
* Create a new empty spaghetti stack, off of the specified parent.
*
* @param par
* The parent stack
*/
public SpaghettiStack(final Stack<T> par) {
backing = new SimpleStack<>();
parent = par;
}
@Override
public void push(final T elm) {
backing.push(elm);
}
@Override
public T pop() {
if (backing.isEmpty())
return parent.pop();
return backing.pop();
}
@Override
public T top() {
if (backing.isEmpty())
return parent.top();
return backing.top();
}
@Override
public int size() {
return parent.size() + backing.size();
}
@Override
public boolean isEmpty() {
return backing.isEmpty() && parent.isEmpty();
}
@SuppressWarnings("unchecked")
@Override
public T[] toArray() {
return (T[]) Stream
.concat(Arrays.stream(parent.toArray()), Arrays.stream(backing.toArray()))
.toArray();
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + (backing == null ? 0 : backing.hashCode());
result = prime * result + (parent == null ? 0 : parent.hashCode());
return result;
}
@Override
public boolean equals(final Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (!(obj instanceof SpaghettiStack<?>))
return false;
final SpaghettiStack<?> other = (SpaghettiStack<?>) obj;
if (backing == null) {
if (other.backing != null)
return false;
} else if (!backing.equals(other.backing))
return false;
if (parent == null) {
if (other.parent != null)
return false;
} else if (!parent.equals(other.parent))
return false;
return true;
}
@Override
public String toString() {
return String.format("SpaghettiStack [backing=%s, parent=%s]", backing, parent);
}
}
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