/*
* 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;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.atomic.AtomicReference;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.geotools.factory.Hints;
import org.geotools.filter.expression.PropertyAccessor;
import org.geotools.filter.expression.PropertyAccessorFactory;
import org.geotools.filter.expression.PropertyAccessors;
import org.geotools.util.Converters;
import org.opengis.feature.simple.SimpleFeatureType;
import org.opengis.feature.type.Name;
import org.opengis.filter.expression.ExpressionVisitor;
import org.opengis.filter.expression.PropertyName;
import org.xml.sax.helpers.NamespaceSupport;
/**
* Defines a complex filter (could also be called logical filter). This filter
* holds one or more filters together and relates them logically in an
* internally defined manner.
*
* @author Rob Hranac, TOPP
*
*
* @source $URL$
* @version $Id$
*/
public class AttributeExpressionImpl extends DefaultExpression implements PropertyName {
/** The logger for the default core module. */
private static final Logger LOGGER = org.geotools.util.logging.Logging.getLogger("org.geotools.core");
/** Holds all sub filters of this filter. */
protected String attPath;
/** Used to validate attribute references to ensure they match the provided schema */
protected SimpleFeatureType schema = null;
/** NamespaceSupport used to defining the prefix information for the xpath expression */
NamespaceSupport namespaceSupport;
/**
* Configures whether evaluate should return null if it cannot find a working
* property accessor, rather than throwing an exception (default behaviour).
* */
protected boolean lenient = true;
/**
* Hints passed to the property accessor gathering up additional context information
* used during evaluation.
*/
private Hints hints;
/**
* Constructor with the schema for this attribute.
*
* @param schema The schema for this attribute.
*/
protected AttributeExpressionImpl(SimpleFeatureType schema) {
this.schema = schema;
}
/**
* Constructor with schema and path to the attribute.
*
* @param xpath the String xpath to the attribute.
*/
public AttributeExpressionImpl( String xpath ){
this.attPath = xpath;
this.schema = null;
this.namespaceSupport = null;
this.hints = null;
}
/**
* Constructor with full attribute name.
*
* @param name Attribute Name.
*/
public AttributeExpressionImpl( Name name ){
attPath = name.getLocalPart();
schema = null;
if (name.getNamespaceURI() != null) {
namespaceSupport = new NamespaceSupport();
namespaceSupport.declarePrefix("", name.getNamespaceURI());
} else {
namespaceSupport = null;
}
}
/**
* Constructor with schema and path to the attribute.
*
* @param xpath the String xpath to the attribute.
* @param namespaceContext Defining the prefix information for the xpath expression
*/
public AttributeExpressionImpl( String xpath, NamespaceSupport namespaceContext ){
attPath = xpath;
schema = null;
this.namespaceSupport = namespaceContext;
}
/**
*
* @param xpath xpath expression
* @param hints Hints passed to the property accessor during evaulation
*/
public AttributeExpressionImpl( String xpath, Hints hints){
attPath = xpath;
schema = null;
this.namespaceSupport = null;
this.hints = hints;
}
public NamespaceSupport getNamespaceContext() {
return namespaceSupport;
}
/**
* Constructor with schema and path to the attribute.
*
* @param schema The initial (required) sub filter.
* @param attPath the xpath to the attribute.
*
* @throws IllegalFilterException If the attribute path is not in the
* schema.
*/
protected AttributeExpressionImpl(SimpleFeatureType schema, String attPath)
throws IllegalFilterException {
this.schema = schema;
setPropertyName(attPath);
}
/**
* Gets the path to the attribute to be evaluated by this expression.
*
* {@link org.opengis.filter.expression.PropertyName#getPropertyName()}
*/
public String getPropertyName() {
return attPath;
}
public void setPropertyName(String attPath) {
LOGGER.entering("ExpressionAttribute", "setAttributePath", attPath);
if(LOGGER.isLoggable(Level.FINEST))
LOGGER.finest("schema: " + schema + "\n\nattribute: " + attPath);
if (schema != null) {
if (schema.getDescriptor(attPath) != null) {
this.attPath = attPath;
} else {
throw new IllegalFilterException(
"Attribute: " +attPath+ " is not in stated schema "+schema.getTypeName()+"."
);
}
} else {
this.attPath = attPath;
}
}
/**
* Gets the value of this property from the passed object.
*
* @param obj Object from which we need to extract a property value.
*/
public Object evaluate(Object obj) {
return evaluate(obj, null);
}
/**
* Gets the value of this attribute from the passed object.
*
* @param obj Object from which to extract attribute value.
* @param target Target Class
*/
@SuppressWarnings("unchecked")
public <T> T evaluate(Object obj, Class<T> target) {
// NC- new method
PropertyAccessor accessor = getLastPropertyAccessor();
AtomicReference<Object> value = new AtomicReference<Object>();
AtomicReference<Exception> e = new AtomicReference<Exception>();
if (accessor == null || !accessor.canHandle(obj, attPath, target)
|| !tryAccessor(accessor, obj, target, value, e)) {
boolean success = false;
if( namespaceSupport != null && hints == null ){
hints = new Hints(PropertyAccessorFactory.NAMESPACE_CONTEXT, namespaceSupport);
}
List<PropertyAccessor> accessors = PropertyAccessors.findPropertyAccessors(obj,
attPath, target, hints );
if (accessors != null) {
Iterator<PropertyAccessor> it = accessors.iterator();
while (!success && it.hasNext()) {
accessor = it.next();
success = tryAccessor(accessor, obj, target, value, e);
}
}
if (!success) {
if (lenient) return null;
else throw new IllegalArgumentException(
"Could not find working property accessor for attribute (" + attPath
+ ") in object (" + obj + ")", e.get());
} else {
setLastPropertyAccessor(accessor);
}
}
if (target == null) {
return (T) value.get();
}
return Converters.convert(value.get(), target);
}
// NC - helper method for evaluation - attempt to use property accessor
private boolean tryAccessor(PropertyAccessor accessor, Object obj, Class<?> target,
AtomicReference<Object> value, AtomicReference<Exception> ex) {
try {
value.set(accessor.get(obj, attPath, target));
return true;
} catch (Exception e) {
ex.set(e);
return false;
}
}
// accessor caching, scanning the registry every time is really very expensive
private PropertyAccessor lastAccessor;
private synchronized PropertyAccessor getLastPropertyAccessor() {
return lastAccessor;
}
private synchronized void setLastPropertyAccessor(PropertyAccessor accessor) {
lastAccessor = accessor;
}
/**
* Return this expression as a string.
*
* @return String representation of this attribute expression.
*/
public String toString() {
return attPath;
}
/**
* Compares this filter to the specified object. Returns true if the
* passed in object is the same as this expression. Checks to make sure
* the expression types are the same as well as the attribute paths and
* schemas.
*
* @param obj - the object to compare this ExpressionAttribute against.
*
* @return true if specified object is equal to this filter; else false
*/
public boolean equals(Object obj) {
if(obj == null)
return false;
if (obj.getClass() == this.getClass()) {
AttributeExpressionImpl expAttr = (AttributeExpressionImpl) obj;
boolean isEqual = (Filters.getExpressionType(expAttr) == Filters.getExpressionType(this));
if(LOGGER.isLoggable(Level.FINEST))
LOGGER.finest("expression type match:" + isEqual + "; in:"
+ Filters.getExpressionType(expAttr) + "; out:" + Filters.getExpressionType(this));
isEqual = (expAttr.attPath != null)
? (isEqual && expAttr.attPath.equals(this.attPath))
: (isEqual && (this.attPath == null));
if(LOGGER.isLoggable(Level.FINEST))
LOGGER.finest("attribute match:" + isEqual + "; in:"
+ expAttr.getPropertyName() + "; out:" + this.attPath);
isEqual = (expAttr.schema != null)
? (isEqual && expAttr.schema.equals(this.schema))
: (isEqual && (this.schema == null));
if(LOGGER.isLoggable(Level.FINEST))
LOGGER.finest("schema match:" + isEqual + "; in:" + expAttr.schema
+ "; out:" + this.schema);
return isEqual;
} else {
return false;
}
}
/**
* Override of hashCode method.
*
* @return a code to hash this object by.
*/
public int hashCode() {
int result = 17;
result = (37 * result) + (attPath == null ? 0 : attPath.hashCode());
result = (37 * result) + (schema == null ? 0 : schema.hashCode());
return result;
}
/**
* Used by FilterVisitors to perform some action on this filter instance.
* Typicaly used by Filter decoders, but may also be used by any thing
* which needs infomration from filter structure. Implementations should
* always call: visitor.visit(this); It is importatant that this is not
* left to a parent class unless the parents API is identical.
*
* @param visitor The visitor which requires access to this filter, the
* method must call visitor.visit(this);
*/
public Object accept(ExpressionVisitor visitor, Object extraData) {
return visitor.visit(this,extraData);
}
/**
* Sets lenient property.
*
* @param lenient
*/
public void setLenient (boolean lenient) {
this.lenient = lenient;
}
/**
* Gets lenient property
*
* @return lenient
*/
public boolean isLenient () {
return lenient;
}
}