64 lines
1.9 KiB
Java
64 lines
1.9 KiB
Java
|
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++];
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
}
|
||
|
|
|