package net.sf.saxon.functions;
import net.sf.saxon.expr.Expression;
import net.sf.saxon.expr.StaticContext;
import net.sf.saxon.om.NamespaceConstant;
import net.sf.saxon.om.StructuredQName;
import net.sf.saxon.sort.IntHashMap;
import net.sf.saxon.trans.Err;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.value.SequenceType;
/**
* The SystemFunctionLibrary represents the collection of functions in the fn: namespace. That is, the
* functions defined in the "Functions and Operators" specification, optionally augmented by the additional
* functions defined in XSLT.
*/
public class SystemFunctionLibrary implements FunctionLibrary {
private int functionSet;
private static IntHashMap<SystemFunctionLibrary> THE_INSTANCES =
new IntHashMap<SystemFunctionLibrary>(3);
/**
* Factory method to create or get a SystemFunctionLibrary
* @param functionSet determines the set of functions allowed. One or more of the bit settings
* {@link StandardFunction#CORE}, {@link StandardFunction#XSLT}, {@link StandardFunction#XQUPDATE}, etc
* @return the appropriate SystemFunctionLibrary
*/
public static SystemFunctionLibrary getSystemFunctionLibrary(int functionSet) {
if (THE_INSTANCES.get(functionSet) == null) {
THE_INSTANCES.put(functionSet, new SystemFunctionLibrary(functionSet));
}
return THE_INSTANCES.get(functionSet);
}
/**
* Create a SystemFunctionLibrary
* @param functionSet determines the set of functions allowed. One or more of the bit settings
* {@link StandardFunction#CORE}, {@link StandardFunction#XSLT}, {@link StandardFunction#XQUPDATE}, etc
*/
private SystemFunctionLibrary(int functionSet) {
this.functionSet = functionSet;
}
/**
* 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.
*
* <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 a zero-length array
* 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) {
String uri = functionName.getNamespaceURI();
String local = functionName.getLocalName();
if (uri.equals(NamespaceConstant.FN)) {
StandardFunction.Entry entry = StandardFunction.getFunction(local, arity);
if (entry == null) {
return null;
}
if (!(arity == -1 || (arity >= entry.minArguments && arity <= entry.maxArguments))) {
return null;
}
if ((functionSet & entry.applicability) == 0) {
return null;
}
SequenceType[] sig = new SequenceType[arity+1];
if (arity >= 0) {
if (entry.itemType == StandardFunction.SAME_AS_FIRST_ARGUMENT) {
sig[0] = entry.argumentTypes[0];
} else {
sig[0] = SequenceType.makeSequenceType(entry.itemType, entry.cardinality);
}
for (int i=0; i<arity; i++) {
if (i < entry.argumentTypes.length) {
sig[i+1] = entry.argumentTypes[i];
} else {
// special path for concat()
sig[i+1] = entry.argumentTypes[0];
}
}
}
return sig;
} else {
return null;
}
}
/**
* 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 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 and arity.
* @throws net.sf.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; or if this function library "owns" the namespace containing
* the function call, but no function was found.
*/
public Expression bind(StructuredQName functionName, Expression[] staticArgs, StaticContext env)
throws XPathException {
String uri = functionName.getNamespaceURI();
if (uri.equals(NamespaceConstant.FN)) {
String local = functionName.getLocalName();
StandardFunction.Entry entry = StandardFunction.getFunction(local, staticArgs.length);
if (entry == null) {
if (StandardFunction.getFunction(local, -1) == null) {
XPathException err = new XPathException("Unknown system function " + local + "()");
err.setErrorCode("XPST0017");
err.setIsStaticError(true);
throw err;
} else {
XPathException err = new XPathException("System function " + local + "() cannot be called with "
+ pluralArguments(staticArgs.length));
err.setErrorCode("XPST0017");
err.setIsStaticError(true);
throw err;
}
}
if ((functionSet & entry.applicability) == 0) {
XPathException err = new XPathException("System function " + local + "() is not available with this host language");
err.setErrorCode("XPST0017");
err.setIsStaticError(true);
throw err;
}
Class functionClass = entry.implementationClass;
SystemFunction f;
try {
f = (SystemFunction)functionClass.newInstance();
} catch (Exception err) {
throw new AssertionError("Failed to load system function: " + err.getMessage());
}
f.setDetails(entry);
f.setFunctionName(functionName);
f.setArguments(staticArgs);
checkArgumentCount(staticArgs.length, entry.minArguments, entry.maxArguments, local);
return f;
} else {
return null;
}
}
/**
* Check number of arguments. <BR>
* A convenience routine for use in subclasses.
* @param numArgs the actual number of arguments (arity)
* @param min the minimum number of arguments allowed
* @param max the maximum number of arguments allowed
* @param local the local name of the function (for diagnostics)
* @return the actual number of arguments
* @throws net.sf.saxon.trans.XPathException if the number of arguments is out of range
*/
private int checkArgumentCount(int numArgs, int min, int max, String local) throws XPathException {
if (min==max && numArgs != min) {
throw new XPathException("Function " + Err.wrap(local, Err.FUNCTION) + " must have "
+ min + pluralArguments(min));
}
if (numArgs < min) {
throw new XPathException("Function " + Err.wrap(local, Err.FUNCTION) + " must have at least "
+ min + pluralArguments(min));
}
if (numArgs > max) {
throw new XPathException("Function " + Err.wrap(local, Err.FUNCTION) + " must have no more than "
+ max + pluralArguments(max));
}
return numArgs;
}
/**
* Utility routine used in constructing error messages
* @param num the number of arguments
* @return the string " argument" or "arguments" depending whether num is plural
*/
private static String pluralArguments(int num) {
if (num==1) return " argument";
return " arguments";
}
/**
* 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() {
return this;
}
}
//
// 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.
//