/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2002-2008, Open Source Geospatial Foundation (OSGeo)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*/
package org.geotools.filter;
// Java Topology Suite dependencies
import java.util.ArrayList;
import java.util.logging.Logger;
import org.opengis.feature.simple.SimpleFeatureType;
import org.xml.sax.Attributes;
import com.vividsolutions.jts.geom.Geometry;
/**
* DOCUMENT ME!
*
* @author Rob Hranac, TOPP<br>
* @author Chris Holmes, TOPP
*
* @source $URL$
* @version $Id$
*/
public class ExpressionSAXParser {
/** The logger for the filter module. */
private static final Logger LOGGER = org.geotools.util.logging.Logging.getLogger("org.geotools.filter");
/** Factory to construct filters. */
private FilterFactory ff;
/** A nested expression parser for math sub expressions */
private ExpressionSAXParser expFactory = null;
/** The current expression being constructed */
private Expression curExprssn = null;
/**
* The current state of the expression. Deterimines if a proper expression
* can be made..
*/
private String currentState = null; //DJB: appears this can be leftValue rightValue complete.
//DJB: added "accumulate" for <Function>
private ArrayList accumalationOfExpressions = new ArrayList(); //DJB: keep a list of the expressions used in a <Function>
/** The type of expression being constructed. */
private String declaredType = null;
/**
* If a expression can be created. Indicates if currentState equals
* complete
*/
private boolean readyFlag = false;
/**
* A schema to read the attributes against. Currently not really
* impelmented.
*/
private SimpleFeatureType schema;
/**
* If the message from the SAX characters function should be read. For
* example when the expression is expecting character values.
*/
private boolean readChars = false;
public ExpressionSAXParser(){
this( FilterFactoryFinder.createFilterFactory() );
}
public ExpressionSAXParser(FilterFactory factory ){
this( null, factory );
}
/**
* Constructor with a schema to read the attribute againset.
*
* @param schema The schema for attributes (null is fine, as the code for
* this is not in place.
*/
public ExpressionSAXParser(SimpleFeatureType schema) {
this( schema, FilterFactoryFinder.createFilterFactory() );
}
/** Constructor injection */
public ExpressionSAXParser( SimpleFeatureType schema, FilterFactory factory ){
this.schema = schema;
ff = factory;
}
/** Setter injection */
public void setFilterFactory( FilterFactory factory ){
ff = factory;
}
/**
* Initializes the factory to create a new expression. Called when the
* filter handler reaches a new expression.
*
* @param declaredType The string representation of the expression type.
*
* @throws IllegalFilterException If there are problems creating
* expressions.
*/
public void start(String declaredType,Attributes atts) throws IllegalFilterException {
LOGGER.finer("incoming type: " + declaredType);
LOGGER.finer("declared type: " + this.declaredType);
LOGGER.finer("current state: " + currentState);
if (expFactory == null)
{
this.declaredType = declaredType;
if (DefaultExpression.isFunctionExpression(convertType(declaredType)))
{
expFactory = new ExpressionSAXParser(schema);
curExprssn = ff.createFunctionExpression( getFunctionName(atts) );
LOGGER.finer("is <function> expression");
}
// if the expression is math, then create a factory for its
// sub expressions, otherwise just instantiate the main expression
if (DefaultExpression.isMathExpression(convertType(declaredType))) {
expFactory = new ExpressionSAXParser(schema);
curExprssn = ff.createMathExpression(convertType(
declaredType));
LOGGER.finer("is math expression");
} else if (DefaultExpression.isLiteralExpression(convertType(
declaredType))) {
curExprssn = ff.createLiteralExpression();
readChars = true;
LOGGER.finer("is literal expression");
} else if (DefaultExpression.isAttributeExpression(convertType(
declaredType))) {
curExprssn = ff.createAttributeExpression(schema);
readChars = true;
LOGGER.finer("is attribute expression");
}
currentState = setInitialState(curExprssn);
readyFlag = false;
} else {
expFactory.start(declaredType,atts);
}
}
/**
* Called when the filter handler has reached the end of an expression
*
* @param message the expression to end.
*
* @throws IllegalFilterException If there are problems creating
* exceptions.
*/
public void end(String message) throws IllegalFilterException {
LOGGER.finer("declared type: " + declaredType);
LOGGER.finer("end message: " + message);
LOGGER.finer("current state: " + currentState);
LOGGER.finest("expression factory: " + expFactory);
// first, check to see if there are internal (nested) expressions
// note that this is identical to checking if the curExprssn
// is a math expression
// if this internal expression exists, send its factory an end message
if (expFactory != null) {
expFactory.end(message);
// if the factory is ready to be returned:
// (1) add its expression to the current expression, as determined
// by the current state
// (2) increment the current state
// (3) set the factory to null to indicate that it is now done
// if in a bad state, throw exception
if (expFactory.isReady()) {
if (currentState.equals("leftValue")) {
((MathExpression) curExprssn).addLeftValue(expFactory
.create());
currentState = "rightValue";
expFactory = new ExpressionSAXParser(schema);
LOGGER.finer("just added left value: " + currentState);
} else if (currentState.equals("rightValue")) {
((MathExpression) curExprssn).addRightValue(expFactory
.create());
currentState = "complete";
expFactory = null;
LOGGER.finer("just added right value: " + currentState);
} else if (currentState.equals("accumulate")) {
accumalationOfExpressions.add(expFactory.create());
expFactory = null;
// currentState = "accumulate"; //leave unchanged
LOGGER.finer("just added a parameter for a function: " + currentState);
if ( ((FunctionExpression) curExprssn).getArgCount() == accumalationOfExpressions.size())
{
//hay, we've parsed all the arguments!
currentState = "complete";
((FunctionExpression) curExprssn).setArgs( (Expression[]) accumalationOfExpressions.toArray( new Expression[0] ));
}
else
{
expFactory = new ExpressionSAXParser(schema); // we're gonna get more expressions
}
} else {
throw new IllegalFilterException(
"Attempted to add sub expression in a bad state: "
+ currentState);
}
}
} else if (declaredType.equals(message)
&& currentState.equals("complete")) {
// if there are no nested expressions here,
// determine if this expression is ready and set flag appropriately
readChars = false;
readyFlag = true;
} else { // otherwise, throw exception
throw new IllegalFilterException(
"Reached end of unready, non-nested expression: "
+ currentState);
}
}
/**
* Checks to see if this expression is ready to be returned.
*
* @return <tt>true</tt> if the expression is ready to be returned,
* <tt>false</tt> otherwise.
*/
public boolean isReady() {
return readyFlag;
}
/**
* Handles incoming characters.
*
* @param message the incoming chars from the SAX handler.
*
* @throws IllegalFilterException If there are problems with filter
* constrcution.
*
* @task TODO: this function is a mess, but it's mostly due to filters
* being loosely coupled with schemas, so we have to make a lot of
* guesses.
* @task TODO: Revisit stripping leading characters. Needed now to get
* things working, and may be the best choice in the end, but it
* should be thought through more.
*/
public void message(String message, boolean convertToNumber) throws IllegalFilterException {
// TODO 2:
// AT SOME POINT MUST MAKE THIS HANDLE A TYPED FEATURE
// BY PASSING IT A FEATURE AND CHECKING ITS TYPE HERE
LOGGER.finer("incoming message: " + message);
LOGGER.finer("should read chars: " + readChars);
if (readChars) {
// If an attribute path, set it. Assumes undeclared type.
if (curExprssn instanceof AttributeExpression) {
LOGGER.finer("...");
//HACK: this code is to get rid of the leading junk that can
//occur in a filter encoding. The '.' is from the .14 wfs spec
//when the style was typeName.propName, such as road.nlanes,
//The ':' is from wfs 1.0 xml request, such as myns:nlanes,
//and the '/' is from wfs 1.0 kvp style: road/nlanes.
//We're not currently checking to see if the typename matches,
// or if the namespace is right, which isn't the best,
//so that should be fixed.
String[] splitName = message.split("[.:/]");
String newAttName = message;
if (splitName.length == 1) {
newAttName = splitName[0];
} else {
//REVISIT: not sure what to do if there are multiple
//delimiters.
//REVISIT: should we examine the first value? See
//if the namespace or typename matches up right?
//this is currently very permissive, just grabs
//the value of the end.
newAttName = splitName[splitName.length - 1];
}
LOGGER.finer("setting attribute expression: " + newAttName);
((AttributeExpression) curExprssn).setAttributePath(newAttName);
LOGGER.finer("...");
currentState = "complete";
LOGGER.finer("...");
} else if (curExprssn instanceof LiteralExpression) {
// This is a relatively loose assignment routine, which uses
// the fact that the three allowed literal types have a strict
// instatiation hierarchy (ie. double can be an int can be a
// string, but not the other way around).
// A better routine would consider the use of this expression
// (ie. will it be compared to a double or searched with a
// like filter?)
//HACK: This should also not use exception catching, it's
//expensive and bad code practice.
if (convertToNumber){
try {
Object temp = new Integer(message);
((LiteralExpression) curExprssn).setLiteral(temp);
currentState = "complete";
} catch (NumberFormatException nfe1) {
try {
Object temp = new Double(message);
((LiteralExpression) curExprssn).setLiteral(temp);
currentState = "complete";
} catch (NumberFormatException nfe2) {
Object temp = message;
((LiteralExpression) curExprssn).setLiteral(temp);
currentState = "complete";
}
}
}else{
Object temp = message;
((LiteralExpression) curExprssn).setLiteral(temp);
currentState = "complete";
}
} else if (expFactory != null) {
expFactory.message(message,convertToNumber);
}
} else if (expFactory != null) {
expFactory.message(message,convertToNumber);
}
}
/**
* Gets geometry.
*
* @param geometry The geometry from the filter.
*
* @throws IllegalFilterException If there are problems creating
* expression.
*/
public void geometry(Geometry geometry) throws IllegalFilterException {
// Sets the geometry for the expression, as appropriate
LOGGER.finer("got geometry: " + geometry.toString());
//if(curExprssn.getType()==ExpressionDefault.LITERAL_GEOMETRY){
//LOGGER.finer("got geometry: ");
curExprssn = ff.createLiteralExpression();
((LiteralExpression) curExprssn).setLiteral(geometry);
LOGGER.finer("set expression: " + curExprssn.toString());
currentState = "complete";
LOGGER.finer("set current state: " + currentState);
// }
}
/**
* Creates and returns the expression.
*
* @return The expression currently held by this parser.
*
* @task REVISIT: shouldn't this check the readyFlag?
*/
public Expression create() {
LOGGER.finer("about to create expression: "
+ curExprssn.toString());
return curExprssn;
}
/**
* Sets the appropriate state.
*
* @param expression the expression being evaluated.
*
* @return <tt>leftValue</tt> if curExprssn is a mathExpression, an
* empty string if a literal or attribute, illegal expression
* thrown otherwise.
*
* @throws IllegalFilterException if the current expression is not math,
* attribute, or literal.
*/
private static String setInitialState(Expression expression)
throws IllegalFilterException {
if (expression instanceof MathExpression) {
return "leftValue";
} else if ((expression instanceof AttributeExpression)
|| (expression instanceof LiteralExpression)) {
return "";
}else if(expression instanceof FunctionExpression)
{
return "accumulate"; // start storing values!
}
else {
throw new IllegalFilterException("Created illegal expression: "
+ expression.getClass().toString());
}
}
/**
* Converts the string representation of the expression to the
* DefaultExpression short type.
*
* @param expType Type of filter for check.
*
* @return the short representation of the expression.
*/
protected static short convertType(String expType) {
// matches all filter types to the default logic type
if (expType.equals("Add")) {
return DefaultExpression.MATH_ADD;
} else if (expType.equals("Sub")) {
return DefaultExpression.MATH_SUBTRACT;
} else if (expType.equals("Mul")) {
return DefaultExpression.MATH_MULTIPLY;
} else if (expType.equals("Div")) {
return DefaultExpression.MATH_DIVIDE;
} else if (expType.equals("PropertyName")) {
return DefaultExpression.ATTRIBUTE_DOUBLE;
} else if (expType.equals("Literal")) {
return DefaultExpression.LITERAL_DOUBLE;
}
else if (expType.equals("Function")) {
return DefaultExpression.FUNCTION;
}
return DefaultExpression.ATTRIBUTE_UNDECLARED;
}
/**
* stolen from the DOM parser -- for a list of attributes, find the "name"
* ie. for <Function name="geomLength"> return "geomLength"
* NOTE: if someone uses <Function name="geomLength"> or <Function ogc:name="geomLength"> this will work,
* if they use a different prefix, it will not.
* @param map
*/
public String getFunctionName(Attributes map)
{
String result = map.getValue("name");
if (result == null)
{
result = map.getValue("ogc:name"); // highly unlikely for this to happen. But, it might...
}
if (result == null)
{
result = map.getValue("ows:name"); // highly unlikely for this to happen. But, it might...
}
return result;
}
}