package net.sf.saxon.xpath;
import net.sf.saxon.expr.Expression;
import net.sf.saxon.expr.StaticContext;
import net.sf.saxon.functions.FunctionLibrary;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.om.StructuredQName;
import net.sf.saxon.value.SequenceType;
import javax.xml.namespace.QName;
import javax.xml.xpath.XPathFunction;
import javax.xml.xpath.XPathFunctionResolver;
/**
* The XPathFunctionLibrary is a FunctionLibrary that supports binding of XPath function
* calls to instances of the JAXP XPathFunction interface returned by an XPathFunctionResolver.
*/
public class XPathFunctionLibrary implements FunctionLibrary {
private XPathFunctionResolver resolver;
/**
* Construct a XPathFunctionLibrary
*/
public XPathFunctionLibrary() {
}
/**
* Set the resolver
* @param resolver The XPathFunctionResolver wrapped by this FunctionLibrary
*/
public void setXPathFunctionResolver(XPathFunctionResolver resolver) {
this.resolver = resolver;
}
/**
* Get the resolver
* @return the XPathFunctionResolver wrapped by this FunctionLibrary
*/
public XPathFunctionResolver getXPathFunctionResolver() {
return resolver;
}
/**
* Test whether a function with a given name and arity is available; if so, return its signature.
* This supports the function-available() function in XSLT; it is also used to support
* higher-order functions introduced in XQuery 1.1. For this function library the method is never
* used and therefore returns null.
*
* <p>This method may be called either at compile time
* or at run time. If the function library is to be used only in an XQuery or free-standing XPath
* environment, this method may throw an UnsupportedOperationException.</p>
* @param functionName the qualified name of the function being called
* @param arity The number of arguments. This is set to -1 in the case of the single-argument
* function-available() function; in this case the method should return true if there is some
* function of this name available for calling.
* @return if a function of this name and arity is available for calling, then the type signature of the
* function, as an array of sequence types in which the zeroth entry represents the return type; or a zero-length
* array if the function exists but the signature is not known; or null if the function does not exist
*/
public SequenceType[] getFunctionSignature(StructuredQName functionName, int arity) {
return null;
}
/**
* Bind a function, given the URI and local parts of the function name,
* and the list of expressions supplied as arguments. This method is called at compile
* time.
* @param functionName
* @param staticArgs The expressions supplied statically in the function call. The intention is
* that the static type of the arguments (obtainable via getItemType() and getCardinality() may
* be used as part of the binding algorithm.
* @param env
* @return An object representing the extension function to be called, if one is found;
* null if no extension function was found matching the required name, arity, or signature.
*/
public Expression bind(StructuredQName functionName, Expression[] staticArgs, StaticContext env)
throws XPathException {
if (resolver == null) {
return null;
}
QName name = new QName(functionName.getNamespaceURI(), functionName.getLocalName());
XPathFunction function = resolver.resolveFunction(name, staticArgs.length);
if (function == null) {
return null;
}
XPathFunctionCall fc = new XPathFunctionCall(function);
fc.setArguments(staticArgs);
return fc;
}
/**
* This method creates a copy of a FunctionLibrary: if the original FunctionLibrary allows
* new functions to be added, then additions to this copy will not affect the original, or
* vice versa.
*
* @return a copy of this function library. This must be an instance of the original class.
*/
public FunctionLibrary copy() {
XPathFunctionLibrary xfl = new XPathFunctionLibrary();
xfl.resolver = resolver;
return xfl;
}
}
//
// The contents of this file are subject to the Mozilla Public License Version 1.0 (the "License");
// you may not use this file except in compliance with the License. You may obtain a copy of the
// License at http://www.mozilla.org/MPL/
//
// Software distributed under the License is distributed on an "AS IS" basis,
// WITHOUT WARRANTY OF ANY KIND, either express or implied.
// See the License for the specific language governing rights and limitations under the License.
//
// The Original Code is: all this file.
//
// The Initial Developer of the Original Code is Michael H. Kay.
//
// Portions created by (your name) are Copyright (C) (your legal entity). All Rights Reserved.
//
// Contributor(s): none.
//