package net.sf.saxon.query;
import net.sf.saxon.Configuration;
import net.sf.saxon.value.SequenceType;
import net.sf.saxon.expr.Expression;
import net.sf.saxon.expr.StaticContext;
import net.sf.saxon.expr.UserFunctionCall;
import net.sf.saxon.functions.FunctionLibrary;
import net.sf.saxon.om.StructuredQName;
import net.sf.saxon.trans.XPathException;
import java.util.ArrayList;
import java.util.List;
/**
* An UnboundFunctionLibrary is not a real function library; rather, it is used to keep track of function calls
* that cannot yet be bound to a known declared function, but will have to be bound when all user-declared functions
* are available.
*/
public class UnboundFunctionLibrary implements FunctionLibrary {
private List unboundFunctionCalls = new ArrayList(20);
private List correspondingStaticContext = new ArrayList(20);
private boolean resolving = false;
/**
* Create an XQueryFunctionLibrary
*/
public UnboundFunctionLibrary() {
}
/**
* Test whether a function with a given name and arity is available. This supports
* the function-available() function in XSLT. Since this library is used only in XQuery,
* and contains no real functions, we always return false
* @param functionName the name of the function required
* @param arity The number of arguments. This is set to -1 in the case of the single-argument
*/
public SequenceType[] getFunctionSignature(StructuredQName functionName, int arity) {
return null;
}
/**
* Identify a (namespace-prefixed) function appearing in the expression. This
* method is called by the XQuery parser to resolve function calls found within
* the query.
* <p>Note that a function call may appear earlier in the query than the definition
* of the function to which it is bound. Unlike XSLT, we cannot search forwards to
* find the function definition. Binding of function calls is therefore a two-stage
* process; at the time the function call is parsed, we simply register it as
* pending; subsequently at the end of query parsing all the pending function
* calls are resolved. Another consequence of this is that we cannot tell at the time
* a function call is parsed whether it is a call to an internal (XSLT or XQuery)
* function or to an extension function written in Java.
* @return an Expression representing the function call. This will normally be
* a FunctionCall, but it may be rewritten as some other expression.
* @throws net.sf.saxon.trans.XPathException if the function call is invalid, either because it is
* an unprefixed call to a non-system function, or because it is calling a system
* function that is available in XSLT only. A prefixed function call that cannot
* be recognized at this stage is assumed to be a forwards reference, and is bound
* later when bindUnboundFunctionCalls() is called.
*/
public Expression bind(StructuredQName functionName, Expression[] arguments, StaticContext env) throws XPathException {
if (resolving) {
return null;
}
UserFunctionCall ufc = new UserFunctionCall();
ufc.setFunctionName(functionName);
ufc.setArguments(arguments);
unboundFunctionCalls.add(ufc);
correspondingStaticContext.add(env);
return ufc;
}
/**
* Bind function calls that could not be bound when first encountered. These
* will either be forwards references to functions declared later in the query,
* or errors. This method is for internal use.
* @param lib A library containing all the XQuery functions that have been declared;
* the method searches this library for this missing function call
* @param config The Saxon configuration
* @throws XPathException if a function call refers to a function that has
* not been declared
*/
public void bindUnboundFunctionCalls(XQueryFunctionBinder lib, Configuration config) throws XPathException {
resolving = true;
for (int i=0; i<unboundFunctionCalls.size(); i++) {
UserFunctionCall ufc = (UserFunctionCall)unboundFunctionCalls.get(i);
QueryModule importingModule = (QueryModule)correspondingStaticContext.get(i);
correspondingStaticContext.set(i, null); // for garbage collection purposes
// The original UserFunctionCall is effectively a dummy: we weren't able to find a function
// definition at the time. So we try again.
final StructuredQName q = ufc.getFunctionName();
final int arity = ufc.getNumberOfArguments();
XQueryFunction fd = lib.getDeclaration(q, ufc.getArguments());
if (fd != null) {
fd.registerReference(ufc);
ufc.setStaticType(fd.getResultType());
ufc.setConfirmed(true);
// Check that the result type and all the argument types are in the static context of the
// calling module
importingModule.checkImportedFunctionSignature(fd);
} else {
String msg = "Cannot find a matching " + arity +
"-argument function named " + q.getClarkName() + "()";
if (!config.isAllowExternalFunctions()) {
msg += ". Note: external function calls have been disabled";
}
XPathException err = new XPathException(msg, ufc);
err.setErrorCode("XPST0017");
err.setIsStaticError(true);
throw err;
}
}
}
/**
* 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() {
UnboundFunctionLibrary qfl = new UnboundFunctionLibrary();
qfl.unboundFunctionCalls = new ArrayList(unboundFunctionCalls);
qfl.correspondingStaticContext = new ArrayList(correspondingStaticContext);
return qfl;
}
}
//
// 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.
//