/*
* The contents of this file are subject to the Mozilla Public License
* Version 1.1 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
* the License for the specific language governing rights and limitations
* under the License.
*
* The Original Code is the Kowari Metadata Store.
*
* The Initial Developer of the Original Code is Plugged In Software Pty
* Ltd (http://www.pisoftware.com, mailto:info@pisoftware.com). Portions
* created by Plugged In Software Pty Ltd are Copyright (C) 2001,2002
* Plugged In Software Pty Ltd. All Rights Reserved.
*
* Contributor(s): N/A.
*
* [NOTE: The text of this Exhibit A may differ slightly from the text
* of the notices in the Source Code files of the Original Code. You
* should use the text of this Exhibit A rather than the text found in the
* Original Code Source Code for Your Modifications.]
*
*/
package org.mulgara.query;
// Java 2 standard packages
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
// Third party packages
import org.apache.log4j.Logger;
import org.jrdf.graph.Node;
/**
* An {@link Answer} backed by a Java array.
*
* @created 2001-07-31
*
* @author <a href="http://staff.pisoftware.com/raboczi">Simon Raboczi</a>
*
* @version $Revision: 1.8 $
*
* @modified $Date: 2005/01/05 04:58:20 $
*
* @maintenanceAuthor $Author: newmana $
*
* @company <A href="mailto:info@PIsoftware.com">Plugged In Software</A>
*
* @copyright © 2001-2004 <a href="http://www.PIsoftware.com/">Plugged In
* Software Pty Ltd</a>
*
* @licence <a href="{@docRoot}/../../LICENCE">Mozilla Public License v1.1</a>
*/
public class ArrayAnswer extends AbstractAnswer implements Answer, Cloneable, Serializable {
/**
* Allow newer compiled version of the stub to operate when changes
* have not occurred with the class.
* NOTE : update this serialVersionUID when a method or a public member is
* deleted.
*/
static final long serialVersionUID = -8428820938720763295L;
/**
* Logger. This is named after the class.
*/
private final static Logger logger =
Logger.getLogger(ArrayAnswer.class.getName());
/**
* The columns of the {@link Answer}.
*/
private Variable[] variables;
/**
* A single array containing the values of all rows.
*
* The length of this array must be an even multiple of the length of the
* {@link #variables} array. The elements of the array must be JRDF
* {@link Node}s, other {@link Answer}s, or <code>null</code> to indicate
* unbound variables.
*/
private Object[] values;
/**
* The cursor position.
*
* Normally cursor positions are <code>long</code>-valued, but since the
* fields are stored in a Java array which only supports
* <code>int</code>-valued indexing, we only support <code>int</code>.
*/
private int row = -1;
/**
* The number of rows.
*
* Normally cursor positions are <code>long</code>-valued, but since the
* fields are stored in a Java array which only supports
* <code>int</code>-valued indexing, we only support <code>int</code>.
*/
private int rowCount;
//
// Constructors
//
/**
* Main constructor.
*
* Note that it's not possible to create an unconstrained {@link Answer} with
* this constructor.
*
* @param variables the columns of the new {@link Answer}, never
* <code>null</code>
* @param values the concatenated rows of the new {@link Answer}, whose
* elements should be either JRDF {@link Node}s, subqueried {@link Answer}s,
* or <code>null</code> to indicate unbound variables
* @throws IllegalArgumentException if either <var>variables</var> or
* <var>values</var> are <code>null</code>, or if the length of the
* <var>values</var> does not divide evenly by the length of the
* <var>variables</var> to produce whole rows, or if the <var>values</var>
* include any element which is not a {@link Node}, an {@link Answer}, or
* <code>null</code>
*/
public ArrayAnswer(Variable[] variables, Object[] values) {
// Validate "variables" parameter
if (variables == null) {
throw new IllegalArgumentException("Null \"variables\" parameter");
}
// Validate "values" parameter
if (values == null) {
throw new IllegalArgumentException("Null \"values\" parameter");
}
if (variables.length == 0) {
if (values.length != 0) {
throw new IllegalArgumentException(
"Non-zero length \"values\" parameter " +
"with zero-length \"variables\" parameter"
);
}
}
else if (values.length % variables.length != 0) {
throw new IllegalArgumentException(
values.length + " values don't make for an integral number of " +
variables.length + "-tuples"
);
}
for (int i = 0; i < values.length; i++) {
if (!((values[i] == null) ||
(values[i] instanceof Node) ||
(values[i] instanceof Answer))) {
throw new IllegalArgumentException(
"Bad element " + i + " in \"values\" parameter: " + values[i] +
" (" +
values[i].getClass() + ")"
);
}
}
// Initialize fields
this.variables = variables;
this.values = values;
this.rowCount = (variables.length == 0)
? 0
: (values.length / variables.length);
}
/**
* Copy constructor.
*
* @param answer the answer to duplicate; <code>null</code> value disallowed
* @throws IllegalArgumentException if <var>answer</var> is <code>null</code>
*/
public ArrayAnswer(Answer answer) throws TuplesException {
// Validate "answer" parameter
if (answer == null) {
throw new IllegalArgumentException("Null \"answer\" parameter");
}
// Copy the variables
variables = answer.getVariables();
assert variables != null:"variables array is null";
// Copy the values
List<Object> valueList = new ArrayList<Object>();
rowCount = 0;
answer.beforeFirst();
while (answer.next()) {
rowCount++;
for (int i = 0; i < variables.length; i++) {
Object object = answer.getObject(i);
// Ensure that any subanswers are Serializable
if (object instanceof Answer && !(object instanceof Serializable)) {
Answer subanswer = (Answer) object;
object = new ArrayAnswer(subanswer);
subanswer.close();
}
valueList.add(object);
}
}
values = valueList.toArray();
}
//
// Methods implementing the Answer interface
//
public long getRowCount() throws TuplesException {
return rowCount;
}
public long getRowUpperBound() throws TuplesException {
return getRowCount();
}
public long getRowExpectedCount() throws TuplesException {
return getRowCount();
}
public int getRowCardinality() throws TuplesException {
if (getRowCount() > 1) {
return Cursor.MANY;
}
switch ((int) getRowCount()) {
case 0:
return Cursor.ZERO;
case 1:
return Cursor.ONE;
default:
throw new TuplesException("Illegal row count: " + getRowCount());
}
}
/* (non-Javadoc)
* @see org.mulgara.query.Cursor#isEmpty()
*/
public boolean isEmpty() throws TuplesException {
return getRowCount() == 0;
}
public Object getObject(int column) throws TuplesException {
if (column < 0 || column >= variables.length) {
throw new IllegalArgumentException("No such column " + column);
}
return values[(variables.length * row) + column];
}
public Object getObject(String columnName) throws TuplesException {
return getObject(getColumnIndex(new Variable(columnName)));
}
public Variable getVariable(int column) throws TuplesException {
if (column < 0 || column >= variables.length) {
throw new IllegalArgumentException("No such column " + column);
}
return variables[column];
}
public Variable[] getVariables() {
return variables;
}
public int getNumberOfVariables() {
return variables.length;
}
public boolean isUnconstrained() throws TuplesException {
return (variables.length == 0) && (rowCount > 0);
}
public int getColumnIndex(Variable column) throws TuplesException {
// Validate "column" parameter
if (column == null) {
throw new IllegalArgumentException("Null \"column\" parameter");
}
// Look for the requested variable in the "variables" array
for (int i = 0; i < variables.length; i++) {
if (column.equals(variables[i])) {
return i;
}
}
// Couldn't find the requested variable
throw new TuplesException("No such column " + column);
}
public void beforeFirst() throws TuplesException {
row = -1;
}
/**
* Free the {@link #variables} and {@link #values} arrays.
*/
public void close() throws TuplesException {
if (variables == null) {
throw new TuplesException("Attempt to close already closed ArrayAnswer.");
}
variables = null;
values = null;
}
public boolean next() throws TuplesException {
if (row < (rowCount - 1)) {
row++;
return true;
}
else {
return false;
}
}
//
// Methods overriding the Object superclass
//
/**
* Subclasses are required to support cloning.
*
* @throws Error if this is a subclass that doesn't support cloning.
*/
public Object clone() {
// Clone all subclass fields
ArrayAnswer cloned;
cloned = (ArrayAnswer)super.clone();
assert cloned != null;
/*
// Copy immutable fields by reference
cloned.rowCount = rowCount;
cloned.variables = variables;
cloned.values = values;
// Copy mutable fields by value
cloned.row = row;
*/
return cloned;
}
/**
* Equality.
*
* @param object the object to compare against for equality, possibly
* <code>null</code>
* @return whether <var>object</var> is equal to this instance; the order of
* both columns and rows is significant
*/
public boolean equals(Object object) {
// Gotta be non-null and of matching type
if ((object != null) && (object instanceof Answer)) {
try {
return AnswerOperations.equal(this, (Answer) object);
}
catch (TuplesException e) {
logger.fatal("Couldn't test equality of answers", e);
}
}
return false;
}
/**
* Added to match {@link #equals(Object)}.
*/
public int hashCode() {
return super.hashCode();
}
/**
* @return a formatted representation of this instance
*/
public String toString() {
if (variables == null) {
return "<closed ArrayAnswer>";
}
StringBuffer stringBuffer = new StringBuffer("[");
// Generate the header
for (int i = 0; i < variables.length; i++) {
stringBuffer.append(variables[i]);
stringBuffer.append((i == variables.length - 1) ? "" : " ");
}
// Generate the content
for (int i = 0; i < values.length; i++) {
stringBuffer.append((i % variables.length == 0) ? "]\n[" : " ");
stringBuffer.append(values[i]);
}
stringBuffer.append("]");
return stringBuffer.toString();
}
}