package org.pdf4j.saxon.query;
import org.pdf4j.saxon.expr.Expression;
import org.pdf4j.saxon.expr.StaticContext;
import org.pdf4j.saxon.functions.FunctionLibrary;
import org.pdf4j.saxon.om.StructuredQName;
import org.pdf4j.saxon.trans.XPathException;
import java.util.HashSet;
import java.util.Iterator;
/**
* This implementation of FunctionLibrary contains all the functions imported into a Query Module.
* It is implemented as a view of the "global" XQueryFunctionLibrary for the whole query, selecting
* only those functions that are in an imported namespace.
*/
public class ImportedFunctionLibrary implements FunctionLibrary, XQueryFunctionBinder {
QueryModule importingModule;
XQueryFunctionLibrary baseLibrary;
HashSet namespaces = new HashSet(5);
/**
* Create an imported function library
* @param importingModule the module importing the library
* @param baseLibrary the function library of which this is a subset view
*/
public ImportedFunctionLibrary(QueryModule importingModule, XQueryFunctionLibrary baseLibrary) {
this.importingModule = importingModule;
this.baseLibrary = baseLibrary;
}
/**
* Add an imported namespace
* @param namespace the imported namespace
*/
public void addImportedNamespace(String namespace) {
namespaces.add(namespace);
}
/**
* Bind an extension 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 to be bound
* @param staticArgs The expressions supplied statically in arguments to the function call.
* The length of this array represents the arity of the function. The intention is
* that the static type of the arguments (obtainable via getItemType() and getCardinality()) may
* be used as part of the binding algorithm. In some cases it may be possible for the function
* to be pre-evaluated at compile time, for example if these expressions are all constant values.
* <p/>
* The conventions of the XPath language demand that the results of a function depend only on the
* values of the expressions supplied as arguments, and not on the form of those expressions. For
* example, the result of f(4) is expected to be the same as f(2+2). The actual expression is supplied
* here to enable the binding mechanism to select the most efficient possible implementation (including
* compile-time pre-evaluation where appropriate).
* @param env
* @return An object representing the function to be called, if one is found;
* null if no function was found matching the required name and arity.
* @throws org.pdf4j.saxon.trans.XPathException
* if a function is found with the required name and arity, but
* the implementation of the function cannot be loaded or used; or if an error occurs
* while searching for the function.
*/
public Expression bind(StructuredQName functionName, Expression[] staticArgs, StaticContext env) throws XPathException {
final String uri = functionName.getNamespaceURI();
if (namespaces.contains(uri)) {
Expression call = baseLibrary.bind(functionName, staticArgs, env);
if (call != null) {
// Check that the result type and all the argument types are in the static context of the
// calling module
XQueryFunction def = baseLibrary.getDeclaration(functionName, staticArgs);
importingModule.checkImportedFunctionSignature(def);
}
return call;
} else {
return null;
}
}
/**
* Get the function declaration corresponding to a given function name and arity
* @return the XQueryFunction if there is one, or null if not.
*/
public XQueryFunction getDeclaration(StructuredQName functionName, Expression[] staticArgs) {
if (namespaces.contains(functionName.getNamespaceURI())) {
return baseLibrary.getDeclaration(functionName, staticArgs);
} else {
return 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.
*/
public FunctionLibrary copy() {
ImportedFunctionLibrary lib = new ImportedFunctionLibrary(importingModule, baseLibrary);
Iterator iter = namespaces.iterator();
while (iter.hasNext()) {
String ns = (String)iter.next();
lib.addImportedNamespace(ns);
}
return lib;
}
/**
* Set the module that imports this function libary
* @param importingModule the importing module
*/
public void setImportingModule(QueryModule importingModule) {
this.importingModule = importingModule;
}
/**
* Test whether an extension function with a given name and arity is available. This supports
* the function-available() function in XSLT. 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.
*
* @param functionName the name of the function in question
* @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
*/
public boolean isAvailable(StructuredQName functionName, int arity) {
return namespaces.contains(functionName.getNamespaceURI()) &&
baseLibrary.isAvailable(functionName, arity);
}
}
//
// 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.
//