001: /*
002: * $Id: AbstractFilteringRowIterator.java,v 1.14 2005/04/22 02:28:53 ahimanikya Exp $
003: * =======================================================================
004: * Copyright (c) 2002-2005 Axion Development Team. All rights reserved.
005: *
006: * Redistribution and use in source and binary forms, with or without
007: * modification, are permitted provided that the following conditions
008: * are met:
009: *
010: * 1. Redistributions of source code must retain the above
011: * copyright notice, this list of conditions and the following
012: * disclaimer.
013: *
014: * 2. Redistributions in binary form must reproduce the above copyright
015: * notice, this list of conditions and the following disclaimer in
016: * the documentation and/or other materials provided with the
017: * distribution.
018: *
019: * 3. The names "Tigris", "Axion", nor the names of its contributors may
020: * not be used to endorse or promote products derived from this
021: * software without specific prior written permission.
022: *
023: * 4. Products derived from this software may not be called "Axion", nor
024: * may "Tigris" or "Axion" appear in their names without specific prior
025: * written permission.
026: *
027: * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
028: * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
029: * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
030: * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
031: * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
032: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
033: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
034: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
035: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
036: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
037: * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
038: * =======================================================================
039: */
040:
041: package org.axiondb.engine.rowiterators;
042:
043: import java.util.NoSuchElementException;
044:
045: import org.axiondb.AxionException;
046: import org.axiondb.Row;
047: import org.axiondb.RowIterator;
048: import org.axiondb.util.ExceptionConverter;
049:
050: /**
051: * @version $Revision: 1.14 $ $Date: 2005/04/22 02:28:53 $
052: * @author Rodney Waldhoff
053: * @author Ahimanikya Satapathy
054: */
055: public abstract class AbstractFilteringRowIterator extends
056: BaseRowIterator {
057:
058: public AbstractFilteringRowIterator(RowIterator iterator) {
059: _delegate = iterator;
060: }
061:
062: public Row current() {
063: if (hasCurrent()) {
064: return _currentRow;
065: }
066: throw new NoSuchElementException("No current row has been set.");
067: }
068:
069: public int currentIndex() {
070: return _currentIndex;
071: }
072:
073: public boolean hasCurrent() {
074: return _currentAvailable;
075: }
076:
077: public boolean hasNext() {
078: if (_nextAvailable) {
079: return true;
080: }
081:
082: try {
083: return determineNextRow();
084: } catch (AxionException e) {
085: throw ExceptionConverter.convertToRuntimeException(e);
086: }
087: }
088:
089: public boolean hasPrevious() {
090: if (_previousAvailable) {
091: return true;
092: }
093:
094: try {
095: return determinePreviousRow();
096: } catch (AxionException e) {
097: throw ExceptionConverter.convertToRuntimeException(e);
098: }
099: }
100:
101: public Row next() throws AxionException {
102: if (!_nextAvailable) {
103: if (!determineNextRow()) {
104: throw new NoSuchElementException();
105: }
106: }
107: _currentIndex = _nextIndex;
108: _nextIndex++;
109: _currentRow = _nextRow;
110: _currentAvailable = true;
111: clearNextRow();
112: return _currentRow;
113: }
114:
115: public int nextIndex() {
116: return _nextIndex;
117: }
118:
119: public Row previous() throws AxionException {
120: if (!_previousAvailable) {
121: if (!determinePreviousRow()) {
122: throw new NoSuchElementException();
123: }
124: }
125: _nextIndex--;
126: _currentIndex = _nextIndex;
127: _currentRow = _previousRow;
128: _currentAvailable = true;
129: clearPreviousRow();
130: return _currentRow;
131: }
132:
133: public int previousIndex() {
134: return (_nextIndex - 1);
135: }
136:
137: public void remove() throws AxionException {
138: if (!hasCurrent()) {
139: throw new IllegalStateException("No current row.");
140: }
141: getDelegate().remove();
142: _nextIndex--;
143: _currentRow = null;
144: _currentAvailable = false;
145: _currentIndex = -1;
146: }
147:
148: public void reset() throws AxionException {
149: _delegate.reset();
150: _previousRow = null;
151: _previousAvailable = false;
152: _nextRow = null;
153: _nextAvailable = false;
154: _nextIndex = 0;
155: _currentRow = null;
156: _currentAvailable = false;
157: _currentIndex = -1;
158: }
159:
160: public void set(Row row) throws AxionException {
161: if (!hasCurrent()) {
162: throw new IllegalStateException("No current row.");
163: }
164: getDelegate().set(row);
165: _currentRow = row;
166: }
167:
168: protected void clearNextRow() {
169: _nextRow = null;
170: _nextAvailable = false;
171: }
172:
173: protected void clearPreviousRow() {
174: _previousRow = null;
175: _previousAvailable = false;
176: }
177:
178: protected abstract boolean determineNextRow() throws AxionException;
179:
180: protected abstract boolean determinePreviousRow()
181: throws AxionException;
182:
183: protected RowIterator getDelegate() {
184: return _delegate;
185: }
186:
187: protected boolean isNextAvailable() {
188: return _nextAvailable;
189: }
190:
191: protected boolean isPreviousAvailable() {
192: return _previousAvailable;
193: }
194:
195: protected void setNext(Row row) {
196: _nextRow = row;
197: _nextAvailable = true;
198: }
199:
200: protected void setPrevious(Row row) {
201: _previousRow = row;
202: _previousAvailable = true;
203: }
204:
205: private boolean _currentAvailable = false;
206: private int _currentIndex = -1;
207: private Row _currentRow = null;
208: private RowIterator _delegate;
209: private boolean _nextAvailable = false;
210: private int _nextIndex = 0;
211: private Row _nextRow = null;
212: private boolean _previousAvailable = false;
213: private Row _previousRow = null;
214: }
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