1 files changed, 75 insertions, 0 deletions
diff --git a/engine/src/android/com/jme3/util/RingBuffer.java b/engine/src/android/com/jme3/util/RingBuffer.java
new file mode 100644
index 0000000..786417b
--- /dev/null
+++ b/engine/src/android/com/jme3/util/RingBuffer.java
@@ -0,0 +1,75 @@
+package com.jme3.util;
+
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+
+/**
+ * Ring buffer (fixed size queue) implementation using a circular array (array with wrap-around).
+ */
+// suppress unchecked warnings in Java 1.5.0_6 and later
+@SuppressWarnings("unchecked")
+public class RingBuffer<Item> implements Iterable<Item> {
+
+    private Item[] buffer;          // queue elements
+    private int count = 0;          // number of elements on queue
+    private int indexOut = 0;       // index of first element of queue
+    private int indexIn = 0;       // index of next available slot
+
+    // cast needed since no generic array creation in Java
+    public RingBuffer(int capacity) {
+        buffer = (Item[]) new Object[capacity];
+    }
+
+    public boolean isEmpty() {
+        return count == 0;
+    }
+
+    public int size() {
+        return count;
+    }
+
+    public void push(Item item) {
+        if (count == buffer.length) {
+            throw new RuntimeException("Ring buffer overflow");
+        }
+        buffer[indexIn] = item;
+        indexIn = (indexIn + 1) % buffer.length;     // wrap-around
+        count++;
+    }
+
+    public Item pop() {
+        if (isEmpty()) {
+            throw new RuntimeException("Ring buffer underflow");
+        }
+        Item item = buffer[indexOut];
+        buffer[indexOut] = null;                  // to help with garbage collection
+        count--;
+        indexOut = (indexOut + 1) % buffer.length; // wrap-around
+        return item;
+    }
+
+    public Iterator<Item> iterator() {
+        return new RingBufferIterator();
+    }
+
+    // an iterator, doesn't implement remove() since it's optional
+    private class RingBufferIterator implements Iterator<Item> {
+
+        private int i = 0;
+
+        public boolean hasNext() {
+            return i < count;
+        }
+
+        public void remove() {
+            throw new UnsupportedOperationException();
+        }
+
+        public Item next() {
+            if (!hasNext()) {
+                throw new NoSuchElementException();
+            }
+            return buffer[i++];
+        }
+    }
+}