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HSQLDB - Lightweight 100% Java SQL Database Engine
/* Copyright (c) 2001-2019, 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.navigator;
import org.hsqldb.Row;
import org.hsqldb.SessionInterface;
import org.hsqldb.error.Error;
import org.hsqldb.error.ErrorCode;
import org.hsqldb.result.ResultMetaData;
import org.hsqldb.rowio.RowInputInterface;
import org.hsqldb.rowio.RowOutputInterface;
/**
* Encapsulates navigation functionality for lists of objects. The base class
* provides positional navigation and checking, while the subclasses provide
* object retrieval.
*
* @author Fred Toussi (fredt@users dot sourceforge.net)
* @version 2.5.0
* @since 1.9.0
*/
public abstract class RowSetNavigator implements RangeIterator {
public RowSetNavigator() {}
SessionInterface session;
long id;
int size;
int mode;
int currentPos = -1;
int rangePosition;
boolean hadNext;
boolean isClosed;
/**
* Sets the id;
*/
public void setId(long id) {
this.id = id;
}
/**
* Returns the id
*/
public long getId() {
return id;
}
/**
* Returns the current row object. Type of object is implementation defined.
*/
public abstract Object[] getCurrent();
public Object getField(int col) {
Object[] current = getCurrent();
if (current == null) {
return null;
}
return current[col];
}
public void setCurrent(Object[] data) {}
public abstract Row getCurrentRow();
/**
* Add data to the end
*/
public abstract void add(Object[] data);
/**
* Add row to the end
*/
public abstract boolean addRow(Row row);
/**
* Remove current row
*/
public abstract void removeCurrent();
/**
* Reset to initial state
*/
public void reset() {
currentPos = -1;
}
/**
* Clear the contents
*/
public abstract void clear();
/**
* Remove any resourses and invalidate
*/
public abstract void release();
public boolean isClosed() {
return isClosed;
}
public void setSession(SessionInterface session) {
this.session = session;
}
public SessionInterface getSession() {
return session;
}
public int getSize() {
return size;
}
public boolean isEmpty() {
return size == 0;
}
public boolean next() {
if (hasNext()) {
currentPos++;
hadNext = true;
return true;
} else if (size != 0) {
currentPos = size;
}
hadNext = false;
return false;
}
final boolean hasNext() {
return currentPos < size - 1;
}
public long getRowId() {
throw Error.runtimeError(ErrorCode.U_S0500, "RowSetNavigator");
}
public boolean hadNext() {
return hadNext;
}
public boolean beforeFirst() {
reset();
currentPos = -1;
return true;
}
public boolean afterLast() {
if (size == 0) {
return false;
}
reset();
currentPos = size;
return true;
}
public boolean first() {
beforeFirst();
return next();
}
public boolean last() {
if (size == 0) {
return false;
}
if (isAfterLast()) {
beforeFirst();
}
while (hasNext()) {
next();
}
return true;
}
public int getRowNumber() {
return currentPos;
}
/**
* Uses similar semantics to java.sql.ResultSet except this is 0 based.
* When position is 0 or positive, it is from the start; when negative,
* it is from end
*/
public boolean absolute(int position) {
if (position < 0) {
position += size;
}
if (position < 0) {
beforeFirst();
return false;
}
if (position >= size) {
afterLast();
return false;
}
if (size == 0) {
return false;
}
if (position < currentPos) {
beforeFirst();
}
// go to the tagget row;
while (position > currentPos) {
next();
}
return true;
}
public boolean relative(int rows) {
int position = currentPos + rows;
if (position < 0) {
beforeFirst();
return false;
}
return absolute(position);
}
public boolean previous() {
return relative(-1);
}
public boolean isFirst() {
return size > 0 && currentPos == 0;
}
public boolean isLast() {
return size > 0 && currentPos == size - 1;
}
public boolean isBeforeFirst() {
return size > 0 && currentPos == -1;
}
public boolean isAfterLast() {
return size > 0 && currentPos == size;
}
public void writeSimple(RowOutputInterface out, ResultMetaData meta) {
throw Error.runtimeError(ErrorCode.U_S0500, "RowSetNavigator");
}
public void readSimple(RowInputInterface in, ResultMetaData meta) {
throw Error.runtimeError(ErrorCode.U_S0500, "RowSetNavigator");
}
public abstract void write(RowOutputInterface out, ResultMetaData meta);
public abstract void read(RowInputInterface in, ResultMetaData meta);
public boolean isMemory() {
return true;
}
public int getRangePosition() {
return rangePosition;
}
}