/*
* eXist Open Source Native XML Database
* Copyright (C) 2001-09 Wolfgang M. Meier
* wolfgang@exist-db.org
* http://exist-db.org
*
* This program 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; either version 2
* of the License, or (at your option) any later version.
*
* This program 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.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id$
*/
package org.exist.xquery.functions.util;
import org.apache.log4j.Logger;
import org.exist.dom.QName;
import org.exist.xquery.Cardinality;
import org.exist.xquery.Function;
import org.exist.xquery.FunctionSignature;
import org.exist.xquery.LocalVariable;
import org.exist.xquery.XPathException;
import org.exist.xquery.XQueryContext;
import org.exist.xquery.value.FunctionParameterSequenceType;
import org.exist.xquery.value.FunctionReturnSequenceType;
import org.exist.xquery.value.Item;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.SequenceIterator;
import org.exist.xquery.value.SequenceType;
import org.exist.xquery.value.StringValue;
import org.exist.xquery.value.Type;
/**
* @author wolf
*/
public class CatchFunction extends Function {
protected static final Logger logger = Logger.getLogger(CatchFunction.class);
public final static FunctionSignature signature =
new FunctionSignature(
new QName("catch", UtilModule.NAMESPACE_URI, UtilModule.PREFIX),
"This function corresponds to a try-catch statement in Java. The code block "
+ "in $try-code-blocks will be put inside a try-catch statement. If an exception "
+ "is thrown while executing $try-code-blocks, the function checks the name of "
+ "the exception and calls $catch-code-blocks if it matches one of "
+ "the fully qualified Java class names specified in $java-classnames. "
+ "A value of \"*\" in $java-classnames will catch all java exceptions. "
+ "Inside the catch code block, the variable $util:exception will be bound to the "
+ "java class name of the exception, "
+ "and $util:exception-message will be bound to the message produced by the exception.",
new SequenceType[]{
new FunctionParameterSequenceType("java-classnames", Type.STRING, Cardinality.ONE_OR_MORE, "The list of one or more fully qualified Java class names. An entry of '*' will catch all java exceptions."),
new FunctionParameterSequenceType("try-code-blocks", Type.ITEM, Cardinality.ZERO_OR_MORE, "The code blocks that will be put inside of a the try part of the try-catch statement."),
new FunctionParameterSequenceType("catch-code-blocks", Type.ITEM, Cardinality.ZERO_OR_MORE, "The code blocks that will be will called if the catch matches one of the $java-classnames")
},
new FunctionReturnSequenceType(Type.ITEM, Cardinality.ZERO_OR_MORE, "the results from the try-catch"),
"Use the XQuery 3.0 try/catch expression instead."
);
/**
* @param context
*/
public CatchFunction(XQueryContext context) {
super(context, signature);
}
/* (non-Javadoc)
* @see org.exist.xquery.Function#eval(org.exist.xquery.value.Sequence, org.exist.xquery.value.Item)
*/
@Override
public Sequence eval(Sequence contextSequence, Item contextItem) throws XPathException {
// Get exception classes
final Sequence exceptionClasses = getArgument(0).eval(contextSequence, contextItem);
Sequence result = null;
// Try to evaluate try-code
try {
context.pushDocumentContext();
final LocalVariable mark = context.markLocalVariables(false);
try {
// Actually execute try-code
result = getArgument(1).eval(contextSequence, contextItem);
return result;
} finally {
context.popDocumentContext();
context.popLocalVariables(mark, result);
}
// Handle exception
} catch (final Exception expException) {
logger.debug("Caught exception in util:catch: " + expException.getMessage());
if (!(expException instanceof XPathException)) {
logger.warn("Exception: " + expException.getMessage(), expException);
}
// context.popDocumentContext();
context.getWatchDog().reset();
// Iterate over all exception parameters
for (final SequenceIterator i = exceptionClasses.iterate(); i.hasNext();) {
final Item currentItem = i.nextItem();
try {
// Get value of execption argument
final String exClassName = currentItem.getStringValue();
Class<?> exClass = null;
// Get exception class, if available
if (!"*".equals(exClassName)) {
exClass = Class.forName(currentItem.getStringValue());
}
// If value is '*' or if class actually matches
if ("*".equals(exClassName)
|| exClass.getName().equals(expException.getClass().getName())
|| exClass.isInstance(expException)) {
logger.debug("Calling exception handler to process " + expException.getClass().getName());
// Make exception name and message available to query
final UtilModule myModule =
(UtilModule) context.getModule(UtilModule.NAMESPACE_URI);
myModule.declareVariable(UtilModule.EXCEPTION_QNAME,
new StringValue(expException.getClass().getName()));
myModule.declareVariable(UtilModule.EXCEPTION_MESSAGE_QNAME,
new StringValue(expException.getMessage()));
// Execute catch-code
return getArgument(2).eval(contextSequence, contextItem);
}
} catch (final Exception e2) {
if (e2 instanceof XPathException) {
throw (XPathException) e2;
} else {
throw new XPathException(this, "Error in exception handler: " + e2.getMessage(), expException);
}
}
}
// this type of exception is not caught: throw again
if (expException instanceof XPathException) {
throw (XPathException) expException;
}
throw new XPathException(this, expException);
}
}
/* (non-Javadoc)
* @see org.exist.xquery.Function#returnsType()
*/
public int returnsType() {
return getArgument(1).returnsType();
}
/* (non-Javadoc)
* @see org.exist.xquery.Function#getCardinality()
*/
public int getCardinality() {
return getArgument(1).getCardinality();
}
}