1 files changed, 89 insertions, 0 deletions
diff --git a/src/main/java/bjc/esodata/QueueStack.java b/src/main/java/bjc/esodata/QueueStack.java
new file mode 100644
index 0000000..49476f0
--- /dev/null
+++ b/src/main/java/bjc/esodata/QueueStack.java
@@ -0,0 +1,89 @@
+package bjc.esodata;
+
+import java.util.Deque;
+import java.util.LinkedList;
+
+/**
+ * A FIFO implementation of a stack.
+ * 
+ * Basically, a stack that actually acts like a queue.
+ *
+ * @param <T>
+ *        The datatype stored in the stack.
+ *
+ * @author Ben Culkin
+ */
+public class QueueStack<T> extends Stack<T> {
+	/* Our backing queue. */
+	private final Deque<T> backing;
+
+	/** Create a new empty stack queue. */
+	public QueueStack() {
+		backing = new LinkedList<>();
+	}
+
+	@Override
+	public void push(final 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(final Object obj) {
+		if(this == obj) return true;
+		if(obj == null) return false;
+		if(!(obj instanceof QueueStack<?>)) return false;
+
+		final QueueStack<?> other = (QueueStack<?>) obj;
+
+		if(backing == null) {
+			if(other.backing != null) return false;
+		} else if(!backing.equals(other.backing)) return false;
+
+		return true;
+	}
+}