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HSQLDB example source code file (HsqlDeque.java)
The HSQLDB HsqlDeque.java source code/* Copyright (c) 2001-2008, The HSQL Development Group * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * Redistributions of source code must retain the above copyright notice, this * list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * * Neither the name of the HSQL Development Group nor the names of its * contributors may be used to endorse or promote products derived from this * software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG, * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ package org.hsqldb.lib; import java.util.NoSuchElementException; // fredt@users 20020130 - patch 1.7.0 by fredt - new class /** * jdk 1.1 compatible minimal implementation of a list object suitable for * stack, queue and deque usage patterns backed by an Object[]. * The memory footprint of the HsqlDeque doubles when it gets full * but does not shrink when it gets empty. * * @author Fred Toussi (fredt@users dot sourceforge.net) * @version 1.9.0 * @since 1.7.0 */ public class HsqlDeque extends BaseList implements HsqlList { private Object[] list; private int firstindex = 0; // index of first list element private int endindex = 0; // index of last list element + 1 // can grow to fill list // if elementCount == 0 then firstindex == endindex private static final int DEFAULT_INITIAL_CAPACITY = 10; public HsqlDeque() { list = new Object[DEFAULT_INITIAL_CAPACITY]; } public int size() { return elementCount; } public boolean isEmpty() { return elementCount == 0; } public Object getFirst() throws NoSuchElementException { if (elementCount == 0) { throw new NoSuchElementException(); } return list[firstindex]; } public Object getLast() throws NoSuchElementException { if (elementCount == 0) { throw new NoSuchElementException(); } return list[endindex - 1]; } public Object get(int i) throws IndexOutOfBoundsException { int index = getInternalIndex(i); return list[index]; } public void add(int i, Object o) throws IndexOutOfBoundsException { throw new java.lang.RuntimeException(); } public Object set(int i, Object o) throws IndexOutOfBoundsException { int index = getInternalIndex(i); Object result = list[index]; list[index] = o; return result; } public Object removeFirst() throws NoSuchElementException { if (elementCount == 0) { throw new NoSuchElementException(); } Object o = list[firstindex]; list[firstindex] = null; firstindex++; elementCount--; if (elementCount == 0) { firstindex = endindex = 0; } else if (firstindex == list.length) { firstindex = 0; } return o; } public Object removeLast() throws NoSuchElementException { if (elementCount == 0) { throw new NoSuchElementException(); } endindex--; Object o = list[endindex]; list[endindex] = null; elementCount--; if (elementCount == 0) { firstindex = endindex = 0; } else if (endindex == 0) { endindex = list.length; } return o; } /* public Object remove(int i){ return get(i); } public void add(int i, Object o) { } */ public boolean add(Object o) { resetCapacity(); if (endindex == list.length) { endindex = 0; } list[endindex] = o; elementCount++; endindex++; return true; } public boolean addLast(Object o) { return add(o); } public boolean addFirst(Object o) { resetCapacity(); firstindex--; if (firstindex < 0) { firstindex = list.length - 1; if (endindex == 0) { endindex = list.length; } } list[firstindex] = o; elementCount++; return true; } public void clear() { if (elementCount == 0) { return; } firstindex = endindex = elementCount = 0; for (int i = 0; i < list.length; i++) { list[i] = null; } } public int indexOf(Object value) { for (int i = 0; i < elementCount; i++) { int index = firstindex + i; if (index >= list.length) { index -= list.length; } if (list[index] == value) { return i; } } return -1; } public Object remove(int index) { int target = getInternalIndex(index); Object value = list[target]; if (target == firstindex) { list[firstindex] = null; firstindex++; if (firstindex == list.length) { firstindex = 0; } } else if (target > firstindex) { System.arraycopy(list, firstindex, list, firstindex + 1, target - firstindex); list[firstindex] = null; firstindex++; if (firstindex == list.length) { firstindex = 0; } } else { System.arraycopy(list, target + 1, list, target, endindex - target - 1); endindex--; list[endindex] = null; if (endindex == 0) { endindex = list.length; } } elementCount--; if (elementCount == 0) { firstindex = endindex = 0; } return value; } private int getInternalIndex(int i) throws IndexOutOfBoundsException { if (i < 0 || i >= elementCount) { throw new IndexOutOfBoundsException(); } int index = firstindex + i; if (index >= list.length) { index -= list.length; } return index; } private void resetCapacity() { if (elementCount < list.length) { return; } Object[] newList = new Object[list.length * 2]; System.arraycopy(list, firstindex, newList, firstindex, list.length - firstindex); if (endindex <= firstindex) { System.arraycopy(list, 0, newList, list.length, endindex); endindex = list.length + endindex; } list = newList; } public void toArray(Object[] array) { int tempCount = list.length - firstindex; if (tempCount > elementCount) { tempCount = elementCount; } System.arraycopy(list, firstindex, array, 0, tempCount); if (endindex <= firstindex) { System.arraycopy(list, 0, array, tempCount, endindex); endindex = list.length + endindex; } } } Other HSQLDB examples (source code examples)Here is a short list of links related to this HSQLDB HsqlDeque.java source code file: |
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