001: /*
002: * $Id: BaseRowIterator.java,v 1.11 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:
049: /**
050: * An abstract base implementation of {@link RowIterator}.
051: *
052: * @version $Revision: 1.11 $ $Date: 2005/04/22 02:28:53 $
053: * @author Rodney Waldhoff
054: * @author Ahimanikya Satapathy
055: */
056: public abstract class BaseRowIterator implements RowIterator {
057: // Note: having these interface methods defined here as abstract seems to keep some
058: // jdk/j2me implementations happy
059:
060: /** Not supported in the base implementation. */
061: public void add(Row row) throws AxionException {
062: throw new UnsupportedOperationException();
063: }
064:
065: public abstract Row current() throws NoSuchElementException;
066:
067: public abstract int currentIndex() throws NoSuchElementException;
068:
069: public Row first() throws AxionException {
070: reset();
071: return peekNext();
072: }
073:
074: public abstract boolean hasCurrent();
075:
076: public abstract boolean hasNext();
077:
078: public abstract boolean hasPrevious();
079:
080: public boolean isEmpty() {
081: return (!hasNext() && !hasPrevious());
082: }
083:
084: public Row last() throws AxionException {
085: if (!hasNext()) {
086: previous(1);
087: }
088:
089: while (hasNext()) {
090: next(1);
091: }
092: return current();
093: }
094:
095: public abstract Row next() throws NoSuchElementException,
096: AxionException;
097:
098: public int next(int count) throws AxionException {
099: for (int i = 0; i < count; i++) {
100: next();
101: }
102: return current().getIdentifier();
103: }
104:
105: public abstract int nextIndex();
106:
107: public Row peekNext() throws AxionException {
108: next(1);
109: return previous();
110: }
111:
112: public Row peekPrevious() throws AxionException {
113: previous(1);
114: return next();
115: }
116:
117: public abstract Row previous() throws NoSuchElementException,
118: AxionException;
119:
120: public int previous(int count) throws AxionException {
121: for (int i = 0; i < count; i++) {
122: previous();
123: }
124: return current().getIdentifier();
125: }
126:
127: public abstract int previousIndex();
128:
129: /** Not supported in the base implementation. */
130: public void remove() throws AxionException {
131: throw new UnsupportedOperationException();
132: }
133:
134: public abstract void reset() throws AxionException;
135:
136: /** Not supported in the base implementation. */
137: public void set(Row row) throws AxionException {
138: throw new UnsupportedOperationException();
139: }
140:
141: public int size() throws AxionException {
142: reset();
143: int count = 0;
144: while (hasNext()) {
145: next(1);
146: count++;
147: }
148: return count;
149: }
150: }
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