1 files changed, 49 insertions, 0 deletions

diff --git a/src/main/java/cuchaz/enigma/gui/util/History.java b/src/main/java/cuchaz/enigma/gui/util/History.java
new file mode 100644
index 0000000..94f3105
--- /dev/null
+++ b/src/main/java/cuchaz/enigma/gui/util/History.java
@@ -0,0 +1,49 @@
+package cuchaz.enigma.gui.util;

+

+import com.google.common.collect.Queues;

+

+import java.util.Deque;

+

+public class History<T> {

+        private final Deque<T> previous = Queues.newArrayDeque();

+        private final Deque<T> next = Queues.newArrayDeque();

+        private T current;

+

+        public History(T initial) {

+                current = initial;

+        }

+

+        public T getCurrent() {

+                return current;

+        }

+

+        public void push(T value) {

+                previous.addLast(current);

+                current = value;

+                next.clear();

+        }

+

+        public void replace(T value) {

+                current = value;

+        }

+

+        public boolean canGoBack() {

+                return !previous.isEmpty();

+        }

+

+        public T goBack() {

+                next.addFirst(current);

+                current = previous.removeLast();

+                return current;

+        }

+

+        public boolean canGoForward() {

+                return !next.isEmpty();

+        }

+

+        public T goForward() {

+                previous.addLast(current);

+                current = next.removeFirst();

+                return current;

+        }

+}