MemStatementList.java

/*
 * Copyright Aduna (http://www.aduna-software.com/) (c) 1997-2006.
 *
 * Licensed under the Aduna BSD-style license.
 */
package org.openrdf.sail.memory.model;

import java.util.Arrays;

/**
 * A dedicated data structure for storing MemStatement objects, offering
 * operations optimized for their use in the memory Sail.
 */
public class MemStatementList {

	/*-----------*
	 * Variables *
	 *-----------*/

	private MemStatement[] statements;

	private int size;

	/*--------------*
	 * Constructors *
	 *--------------*/

	/**
	 * Creates a new MemStatementList.
	 */
	public MemStatementList() {
		this(4);
	}

	public MemStatementList(int capacity) {
		statements = new MemStatement[capacity];
		size = 0;
	}

	public MemStatementList(MemStatementList other) {
		this(other.size);
		addAll(other);
	}

	/*---------*
	 * Methods *
	 *---------*/

	public int size() {
		return size;
	}

	public boolean isEmpty() {
		return size == 0;
	}

	public MemStatement get(int index) {
		if (index < 0 || index >= size) {
			if (index < 0) {
				throw new IndexOutOfBoundsException("index < 0");
			}
			else {
				throw new IndexOutOfBoundsException("index >= size");
			}
		}

		return statements[index];
	}

	public void add(MemStatement st) {
		if (size == statements.length) {
			// Grow array
			growArray((size == 0) ? 1 : 2 * size);
		}

		statements[size] = st;
		++size;
	}

	public void addAll(MemStatementList other) {
		if (size + other.size >= statements.length) {
			// Grow array
			growArray(size + other.size);
		}

		System.arraycopy(other.statements, 0, statements, size, other.size);
		size += other.size;
	}

	public void remove(int index) {
		if (index < 0 || index >= size) {
			if (index < 0) {
				throw new IndexOutOfBoundsException("index < 0");
			}
			else {
				throw new IndexOutOfBoundsException("index >= size");
			}
		}

		if (index == size - 1) {
			// Last statement in array
			statements[index] = null;
			--size;
		}
		else {
			// Not last statement in array, move last
			// statement over the one at [index]
			--size;
			statements[index] = statements[size];
			statements[size] = null;
		}
	}

	public void remove(MemStatement st) {
		for (int i = 0; i < size; ++i) {
			if (statements[i] == st) {
				remove(i);
				return;
			}
		}
	}

	public void clear() {
		Arrays.fill(statements, 0, size, null);
		size = 0;
	}

	private void growArray(int newSize) {
		MemStatement[] newArray = new MemStatement[newSize];
		System.arraycopy(statements, 0, newArray, 0, size);
		statements = newArray;
	}
}