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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.functions;
import net.sf.saxon.Configuration;
import net.sf.saxon.expr.Expression;
import net.sf.saxon.expr.StaticContext;
import net.sf.saxon.expr.UserFunctionCall;
import net.sf.saxon.expr.instruct.UserFunction;
import net.sf.saxon.om.Function;
import net.sf.saxon.trans.SymbolicName;
import net.sf.saxon.trans.XPathException;
import java.util.HashMap;
import java.util.List;
/**
* 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.
*/
public class ExecutableFunctionLibrary implements FunctionLibrary {
private final transient Configuration config;
private HashMap functions = new HashMap<>(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;
}
/**
* Register a function with the function library
*
* @param fn the function to be registered
*/
public void addFunction(UserFunction fn) {
functions.put(fn.getSymbolicName(), fn);
}
/**
* 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 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 and arity.
*/
@Override
public Expression bind(SymbolicName.F functionName, Expression[] staticArgs, StaticContext env, List reasons) {
UserFunction fn = functions.get(functionName);
if (fn == null) {
return null;
}
UserFunctionCall fc = new UserFunctionCall();
fc.setFunctionName(functionName.getComponentName());
fc.setArguments(staticArgs);
fc.setFunction(fn);
fc.setStaticType(fn.getResultType());
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 functionName 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 functionName, StaticContext staticContext) throws XPathException {
UserFunction fn = functions.get(functionName);
if (fn != null && fn.isUpdating()) {
throw new XPathException("Cannot bind a function item to an updating function");
}
return fn;
}
/**
* 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 (31 = 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 functions.get(functionName) != 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.
*/
@Override
public FunctionLibrary copy() {
ExecutableFunctionLibrary efl = new ExecutableFunctionLibrary(config);
efl.functions = new HashMap<>(functions);
return efl;
}
/**
* Get all the functions defined in this function library.
*
* @return an iterable delivering the {@link UserFunction} objects representing
* the user-defined functions in a stylesheet or query
*/
public Iterable getAllFunctions() {
return functions.values();
}
}