/*
* eXist Open Source Native XML Database
* Copyright (C) 2005-09 The eXist Project
* 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.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.exist.dom.QName;
import org.exist.xquery.*;
import org.exist.xquery.util.Error;
import org.exist.xquery.util.Messages;
import org.exist.xquery.value.*;
/**
* @author wolf
*/
public class FunctionFunction extends BasicFunction {
protected static final Logger logger = LogManager.getLogger(FunctionFunction.class);
protected static final FunctionParameterSequenceType functionName = new FunctionParameterSequenceType("name", Type.QNAME, Cardinality.EXACTLY_ONE, "The name of the function");
protected static final FunctionParameterSequenceType arity = new FunctionParameterSequenceType("arity", Type.INTEGER, Cardinality.EXACTLY_ONE, "The arity of the function");
protected static final FunctionReturnSequenceType result = new FunctionReturnSequenceType(Type.FUNCTION_REFERENCE, Cardinality.EXACTLY_ONE, "the reference to the XQuery function");
public final static FunctionSignature signature =
new FunctionSignature(
new QName("function", UtilModule.NAMESPACE_URI, UtilModule.PREFIX),
"Creates a reference to an XQuery function which can later be called from util:call. " +
"This allows for higher-order functions to be implemented in XQuery. A higher-order " +
"function is a function that takes another function as argument. " +
"The first argument represents the name of the function, which should be" +
"a valid QName. The second argument is the arity (number of parameters) of " +
"the function. If no function can be found that matches the name and arity, " +
"an error is thrown. " +
"Please note: the arguments to this function " +
"have to be literals or need to be resolvable at compile time at least.",
new SequenceType[] { functionName, arity },
result
);
private FunctionCall resolvedFunction = null;
/**
* @param context
*/
public FunctionFunction(XQueryContext context) {
super(context, signature);
}
public void analyze(AnalyzeContextInfo contextInfo) throws XPathException {
super.analyze(contextInfo);
final String funcName = getArgument(0).eval(null).getStringValue();
final int arity = ((NumericValue)getArgument(1).eval(null).itemAt(0)).getInt();
final FunctionCall funcCall = lookupFunction(funcName, arity);
contextInfo.addFlag(SINGLE_STEP_EXECUTION);
funcCall.analyze(contextInfo);
}
/* (non-Javadoc)
* @see org.exist.xquery.BasicFunction#eval(org.exist.xquery.value.Sequence[], org.exist.xquery.value.Sequence)
*/
public Sequence eval(Sequence[] args, Sequence contextSequence)
throws XPathException {
final String funcName = args[0].getStringValue();
final int arity = ((NumericValue) args[1].itemAt(0)).getInt();
this.resolvedFunction = lookupFunction(funcName, arity);
return new FunctionReference(resolvedFunction);
}
private FunctionCall lookupFunction(String funcName, int arity) throws XPathException {
// try to parse the qname
QName qname;
try {
qname = QName.parse(context, funcName, context.getDefaultFunctionNamespace());
} catch(final XPathException e) {
e.setLocation(line, column);
throw e;
}
// check if the function is from a module
final Module module = context.getModule(qname.getNamespaceURI());
UserDefinedFunction func;
if(module == null) {
func = context.resolveFunction(qname, arity);
} else {
if(module.isInternalModule()) {
logger.error("Cannot create a reference to an internal Java function");
throw new XPathException(this, "Cannot create a reference to an internal Java function");
}
func = ((ExternalModule)module).getFunction(qname, arity, context);
}
if (func == null)
{throw new XPathException(this, Messages.getMessage(Error.FUNC_NOT_FOUND, qname, Integer.toString(arity)));}
final FunctionCall funcCall = new FunctionCall(context, func);
funcCall.setLocation(line, column);
return funcCall;
}
public void resetState(boolean postOptimization) {
super.resetState(postOptimization);
if (resolvedFunction != null)
{resolvedFunction.resetState(postOptimization);}
if (!postOptimization)
{resolvedFunction = null;}
}
}