/*
* eXist Open Source Native XML Database
* Copyright (C) 2001-09 Wolfgang M. Meier
* wolfgang@exist-db.org
* http://exist.sourceforge.net
*
* 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.system;
import org.apache.log4j.Logger;
import org.exist.dom.QName;
import org.exist.xquery.BasicFunction;
import org.exist.xquery.Cardinality;
import org.exist.xquery.ExternalModule;
import org.exist.xquery.FunctionSignature;
import org.exist.xquery.InternalModule;
import org.exist.xquery.Module;
import org.exist.xquery.XPathException;
import org.exist.xquery.XQueryContext;
import org.exist.xquery.value.BooleanValue;
import org.exist.xquery.value.FunctionParameterSequenceType;
import org.exist.xquery.value.FunctionReturnSequenceType;
import org.exist.xquery.value.IntegerValue;
import org.exist.xquery.value.QNameValue;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.SequenceType;
import org.exist.xquery.value.Type;
/**
* Return whether the function is available
*
* @author Adam Retter <adam@exist-db.org>
*/
public class FunctionAvailable extends BasicFunction {
protected final static Logger logger = Logger.getLogger(FunctionAvailable.class);
public final static FunctionSignature signature =
new FunctionSignature(
new QName("function-available", SystemModule.NAMESPACE_URI, SystemModule.PREFIX),
"Returns whether a function is available.",
new SequenceType[]{
new FunctionParameterSequenceType("function-name", Type.QNAME, Cardinality.ONE, "The fully qualified name of the function"),
new FunctionParameterSequenceType("arity", Type.INTEGER, Cardinality.ONE, "The arity of the function")
},
new FunctionReturnSequenceType(Type.BOOLEAN, Cardinality.EXACTLY_ONE, "true() if the function exists, false() otherwise."));
public FunctionAvailable(XQueryContext context) {
super(context, signature);
}
/* (non-Javadoc)
* @see org.exist.xquery.BasicFunction#eval(org.exist.xquery.value.Sequence[], org.exist.xquery.value.Sequence)
*/
@Override
public Sequence eval(Sequence[] args, Sequence contextSequence) throws XPathException {
final QName functionName = ((QNameValue)args[0].itemAt(0)).getQName();
final int arity = ((IntegerValue)args[1].itemAt(0)).getInt();
final Module module = context.getModule(functionName.getNamespaceURI());
boolean found = false;
if(module == null) {
found = context.resolveFunction(functionName, arity) != null;
} else {
if(module instanceof InternalModule) {
found = ((InternalModule)module).getFunctionDef(functionName, arity) != null;
} else if(module instanceof ExternalModule) {
found = ((ExternalModule)module).getFunction(functionName, arity, context) != null;
}
}
return BooleanValue.valueOf(found);
}
}