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An OSGi bundle for Saxon-HE
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2013 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.expr.Container;
import net.sf.saxon.expr.Expression;
import net.sf.saxon.expr.StaticContext;
import net.sf.saxon.lib.ExtensionFunctionCall;
import net.sf.saxon.lib.ExtensionFunctionDefinition;
import net.sf.saxon.om.FunctionItem;
import net.sf.saxon.om.StructuredQName;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.FunctionItemType;
import java.io.Serializable;
import java.util.HashMap;
/**
* A library of integrated function calls, that is, user-written extension functions implemented
* as instances of the class IntegratedFunction.
*/
public class IntegratedFunctionLibrary implements FunctionLibrary, Serializable {
private HashMap functions =
new HashMap();
/**
* Register an integrated function with this function library
* @param function the implementation of the function (or set of functions)
*/
public void registerFunction(ExtensionFunctionDefinition function) {
functions.put(function.getFunctionQName(), function);
}
/**
* 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 QName of the function being called
* @param arity
* @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.
*
* 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 The static context of the function call
* @param container
* @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 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.
*/
public Expression bind(StructuredQName functionName, int arity, Expression[] staticArgs, StaticContext env, Container container)
throws XPathException {
ExtensionFunctionDefinition defn = functions.get(functionName);
if (defn == null) {
return null;
}
try {
return makeFunctionCall(defn, staticArgs, container);
} catch (Exception err) {
throw new XPathException("Failed to create call to extension function " + functionName.getDisplayName(), err);
}
}
public static Expression makeFunctionCall(ExtensionFunctionDefinition defn, Expression[] staticArgs, Container container) {
ExtensionFunctionCall f = defn.makeCallExpression();
f.setDefinition(defn, container);
IntegratedFunctionCall fc = new IntegratedFunctionCall(f);
fc.setFunctionName(defn.getFunctionQName());
fc.setArguments(staticArgs);
return fc;
}
/**
* 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 arity The number of arguments.
* @return true if a function of this name and arity is available for calling
*/
public boolean isAvailable(StructuredQName functionName, int arity) {
ExtensionFunctionDefinition defn = functions.get(functionName);
return defn != null && defn.getMaximumNumberOfArguments() >= arity && defn.getMinimumNumberOfArguments() <= arity;
}
/**
* 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() {
IntegratedFunctionLibrary lib = new IntegratedFunctionLibrary();
lib.functions = new HashMap(functions);
return lib;
}
}