package client.net.sf.saxon.ce.functions;
import client.net.sf.saxon.ce.Configuration;
import client.net.sf.saxon.ce.expr.*;
import client.net.sf.saxon.ce.expr.instruct.UserFunction;
import client.net.sf.saxon.ce.om.StructuredQName;
import client.net.sf.saxon.ce.trans.XPathException;
import client.net.sf.saxon.ce.tree.util.FastStringBuffer;
import java.util.HashMap;
import java.util.Iterator;
/**
* An ExecutableFunctionLibrary is a function library that contains definitions of functions for use at
* run-time. Normally functions are bound at compile-time; however there are various situations in which
* the information is needed dynamically, for example (a) to support the XSLT function-available() call
* (in the pathological case where the argument is not known statically), (b) to allow functions to be
* called from saxon:evaluate(), (c) to allow functions to be called from a debugging breakpoint.
*
* The objects actually held in the ExecutableFunctionLibrary are UserFunctionCall objects that have been
* prepared at compile time. These are function calls that do full dynamic type checking: that is, they
* are prepared on the basis that the static types of the arguments are all "item()*", meaning that full
* type checking is needed at run-time.
*/
public class ExecutableFunctionLibrary implements FunctionLibrary {
private transient Configuration config;
private HashMap<String, UserFunction> functions = new HashMap<String, UserFunction>(20);
// The key of the hash table is a String that combines the QName of the function with the arity.
/**
* Create the ExecutableFunctionLibrary
* @param config the Saxon configuration
*/
public ExecutableFunctionLibrary(Configuration config) {
this.config = config;
}
/**
* Make a key that will uniquely identify a function
* @param functionName the name of the function
* @param arity the number of arguments
* @return the constructed key. This is of the form {uri}local/arity
*/
private String makeKey(StructuredQName functionName, int arity) {
String uri = functionName.getNamespaceURI();
String local = functionName.getLocalName();
FastStringBuffer sb = new FastStringBuffer(uri.length() + local.length() + 8);
sb.append('{');
sb.append(uri);
sb.append('}');
sb.append(local);
sb.append("#" + arity);
return sb.toString();
}
/**
* Register a function with the function library
* @param fn the function to be registered
*/
public void addFunction(UserFunction fn) {
functions.put(makeKey(fn.getFunctionName(), fn.getNumberOfArguments()), fn);
}
/**
* 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 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 boolean hasFunctionSignature(StructuredQName functionName, int arity) {
if (arity == -1) {
for (int i=0; i<=20; i++) {
boolean b = hasFunctionSignature(functionName, i);
if (b) return true;
}
return false;
}
UserFunction uf = functions.get(makeKey(functionName, arity));
return uf != 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 The name of the function to be called
* @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 evaluation context
* @param container
* @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 client.net.sf.saxon.ce.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, Container container)
throws XPathException {
UserFunction fn = functions.get(makeKey(functionName, staticArgs.length));
if (fn == null) {
return null;
}
ExpressionVisitor visitor = ExpressionVisitor.make(env, fn.getExecutable());
UserFunctionCall fc = new UserFunctionCall();
fc.setFunctionName(functionName);
fc.setArguments(staticArgs);
fc.setFunction(fn);
fc.checkFunctionCall(fn, visitor);
fc.setStaticType(fn.getResultType(config.getTypeHierarchy()));
return fc;
}
/**
* Iterate over all the functions defined in this function library. The objects
* returned by the iterator are of class {@link UserFunction}
* @return an iterator delivering the {@link UserFunction} objects representing
* the user-defined functions in a stylesheet or query
*/
public Iterator<UserFunction> iterateFunctions() {
return functions.values().iterator();
}
}
// 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.