001: /*
002: * $Id: AbstractAcceptingRowIterator.java,v 1.5 2005/04/08 13:40:43 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 org.axiondb.AxionException;
044: import org.axiondb.Row;
045: import org.axiondb.RowIterator;
046:
047: /**
048: * Abstract base {@link DelegatingRowIterator}that excludes {@link Row}s that are not
049: * {@link #acceptable acceptable}.
050: *
051: * @version $Revision: 1.5 $ $Date: 2005/04/08 13:40:43 $
052: * @author Rodney Waldhoff
053: */
054: public abstract class AbstractAcceptingRowIterator extends
055: AbstractFilteringRowIterator {
056:
057: public AbstractAcceptingRowIterator(RowIterator iterator) {
058: super (iterator);
059: }
060:
061: public void set(Row row) throws AxionException {
062: if (acceptable(currentIndex(), row)) {
063: super .set(row);
064: } else {
065: throw new IllegalStateException("Out of range");
066: }
067: }
068:
069: /**
070: * My filtering method. Return <code>true</code> if the given {@link Row}should be
071: * included in the iteration, <code>false</code> otherwise.
072: */
073: protected abstract boolean acceptable(int rowindex, Row row)
074: throws AxionException;
075:
076: protected boolean determineNextRow() throws AxionException {
077: // if _previousRowSet is true, then we've walked back in the delegate list
078: // so skip one matching row
079: if (isPreviousAvailable()) {
080: clearPreviousRow();
081: determineNextRow();
082: clearNextRow();
083: }
084:
085: while (getDelegate().hasNext()) {
086: Row row = getDelegate().next();
087: if (acceptable(nextIndex(), row)) {
088: setNext(row);
089: return true;
090: }
091: }
092: return false;
093: }
094:
095: protected boolean determinePreviousRow() throws AxionException {
096: // if _nextRowSet is true, then we've walked forward in the delegate list
097: // so skip one matching row
098: if (isNextAvailable()) {
099: clearNextRow();
100: determinePreviousRow();
101: clearPreviousRow();
102: }
103:
104: while (getDelegate().hasPrevious()) {
105: Row row = getDelegate().previous();
106: if (acceptable(previousIndex(), row)) {
107: setPrevious(row);
108: return true;
109: }
110: }
111: return false;
112: }
113: }
|