1 files changed, 102 insertions, 0 deletions
diff --git a/src/main/java/bjc/esodata/SpaghettiStack.java b/src/main/java/bjc/esodata/SpaghettiStack.java
new file mode 100644
index 0000000..9280c28
--- /dev/null
+++ b/src/main/java/bjc/esodata/SpaghettiStack.java
@@ -0,0 +1,102 @@
+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.empty()) return parent.pop();
+
+		return backing.pop();
+	}
+
+	@Override
+	public T top() {
+		if(backing.empty()) return parent.top();
+
+		return backing.top();
+	}
+
+	@Override
+	public int size() {
+		return parent.size() + backing.size();
+	}
+
+	@Override
+	public boolean empty() {
+		return backing.empty() && parent.empty();
+	}
+
+	@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);
+	}
+}