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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2018-2022 Saxonica Limited
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
package net.sf.saxon.xpath;
import net.sf.saxon.functions.CallableFunction;
import net.sf.saxon.type.SpecificFunctionType;
import net.sf.saxon.expr.Expression;
import net.sf.saxon.expr.StaticContext;
import net.sf.saxon.functions.FunctionLibrary;
import net.sf.saxon.om.Function;
import net.sf.saxon.om.StructuredQName;
import net.sf.saxon.trans.SymbolicName;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.FunctionItemType;
import net.sf.saxon.value.SequenceType;
import javax.xml.namespace.QName;
import javax.xml.xpath.XPathFunction;
import javax.xml.xpath.XPathFunctionResolver;
import java.util.Arrays;
import java.util.List;
/**
* 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;
}
/**
* 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 The name of the function
* @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 The static context
* @param reasons If no matching function is found by the function library, it may add
* a diagnostic explanation to this list explaining why none of the available
* functions could be used.
* @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.
*/
/*@Nullable*/
@Override
public Expression bind(/*@NotNull*/ SymbolicName.F functionName, /*@NotNull*/ Expression[] staticArgs, StaticContext env, List reasons) {
if (resolver == null) {
return null;
}
StructuredQName qn = functionName.getComponentName();
QName name = new QName(qn.getURI(), qn.getLocalPart());
XPathFunction function = resolver.resolveFunction(name, functionName.getArity());
if (function == null) {
return null;
}
XPathFunctionCall fc = new XPathFunctionCall(qn, function);
fc.setArguments(staticArgs);
return fc;
}
/**
* Test whether a function with a given name and arity is available; if so, return a function
* item that can be dynamically called.
* This supports the function-lookup() function in XPath 3.0.
*
* @param symbolicName the qualified name of the function being called
* @param staticContext the static context to be used by the function, in the event that
* it is a system function with dependencies on the static context
* @return if a function of this name and arity is available for calling, then a corresponding
* function item; or null if the function does not exist
* @throws net.sf.saxon.trans.XPathException
* in the event of certain errors, for example attempting to get a function
* that is private
*/
@Override
public Function getFunctionItem(SymbolicName.F symbolicName, StaticContext staticContext) throws XPathException {
if (resolver == null) {
return null;
}
StructuredQName functionName = symbolicName.getComponentName();
int arity = symbolicName.getArity();
QName name = new QName(functionName.getURI(), functionName.getLocalPart());
XPathFunction function = resolver.resolveFunction(name, arity);
if (function == null) {
return null;
}
XPathFunctionCall functionCall = new XPathFunctionCall(functionName, function);
SequenceType[] argTypes = new SequenceType[arity];
Arrays.fill(argTypes, SequenceType.ANY_SEQUENCE);
FunctionItemType functionType = new SpecificFunctionType(argTypes, SequenceType.ANY_SEQUENCE);
return new CallableFunction(symbolicName, functionCall, functionType);
}
/**
* Test whether a function with a given name and arity is available
* This supports the function-available() function in XSLT.
*
* @param functionName the qualified name of the function being called
* @param languageLevel the XPath language level (times 10, e.g. 31 for XPath 3.1)
* @return true if a function of this name and arity is available for calling
*/
@Override
public boolean isAvailable(SymbolicName.F functionName, int languageLevel) {
return resolver != null &&
resolver.resolveFunction(
new QName(functionName.getComponentName().getURI(), functionName.getComponentName().getLocalPart()),
functionName.getArity()) != null;
}
/**
* 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.
*/
/*@NotNull*/
@Override
public FunctionLibrary copy() {
XPathFunctionLibrary xfl = new XPathFunctionLibrary();
xfl.resolver = resolver;
return xfl;
}
}