CircularBuffer.mon

package com.apamax.containers;

/**
 * A fixed-sized circular buffer object.
 * 
 * Once the buffer is full, adding another value removes the oldest one in the buffer.
 */
event FixedSizeCircularBuffer
{
	/** Create an empty buffer of a particular size.
	 * @param size The maximum capacity of the buffer.
	 */
	static action create(integer size) returns FixedSizeCircularBuffer
	{
		FixedSizeCircularBuffer buf := new FixedSizeCircularBuffer;
		buf.data.setCapacity(size);
		buf._capacity := size;
		return buf;
	}
	/** Push a value onto the buffer.
	 * If the buffer is full, removes the oldest value.
	 * @param val The value to add to the buffer.
	 */
	action push(any val)
	{
		data.append(val);
		if data.size() > _capacity {
			data.remove(0);
		}
	}
	/** Return the item currently at the given position in the buffer.
	 * @param offs The offset into the buffer, with 0 being the oldest and capacity-1 being the most recent.
	 */
	action get(integer offs) returns any
	{
		return data[offs];
	}
	/** Return the underlying sequence containing the circular buffer in order. 
	 * This is returned by reference. You should not modify the return value, only clone it or iterate over it.
	 */
	action getData() returns sequence<any>
	{
		return data;
	}
	/** Return the capacity of this circular buffer. */
	action capacity() returns integer
	{
		return _capacity;
	}
	/** Return the number of values in the buffer. */
	action size() returns integer
	{
		return data.size();
	}
	/** Returns true if the buffer is empty. */
	action empty() returns boolean
	{
		return data.size()=0;
	}
	/** Returns true if the buffer is full (size() == capacity()). */
	action full() returns boolean
	{
		return data.size()=_capacity;
	}
	/** Remove all the values in the buffer. */
	action clear()
	{
		data.clear();
	}

	/** @private */
	sequence<any> data;
	/** @private */
	integer _capacity;
}