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The XSLT and XQuery Processor
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// 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.style;
import net.sf.saxon.expr.Component;
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.expr.parser.ExpressionVisitor;
import net.sf.saxon.functions.FunctionLibrary;
import net.sf.saxon.om.Function;
import net.sf.saxon.trans.SymbolicName;
import net.sf.saxon.trans.XPathException;
import java.util.List;
/**
* A StylesheetFunctionLibrary contains functions defined by the user in a stylesheet. This library is used at
* compile time only, as it contains references to the actual XSLFunction objects. Binding to a function in this
* library registers the function call on a fix-up list to be notified when the actual compiled function becomes
* available.
*/
public class StylesheetFunctionLibrary implements FunctionLibrary {
private final StylesheetPackage pack;
private final boolean overrideExtensionFunction;
/**
* Create a FunctionLibrary that provides access to stylesheet functions
*
* @param sheet The XSLT package
* @param overrideExtensionFunction set to true if this library is to contain functions specifying override="yes",
* or to false if it is to contain functions specifying override="no". (XSLT uses two instances
* of this class, one for overrideExtensionFunction functions and one for non-overrideExtensionFunction functions.)
*/
public StylesheetFunctionLibrary(StylesheetPackage sheet, boolean overrideExtensionFunction) {
this.pack = sheet;
this.overrideExtensionFunction = overrideExtensionFunction;
}
/**
* Ask whether the functions in this library are "overrideExtensionFunction" functions, that is, defined with
* xsl:function override="yes".
*
* @return true if these are overrideExtensionFunction functions, false otherwise
*/
public boolean isOverrideExtensionFunction() {
return overrideExtensionFunction;
}
/**
* Get the stylesheet package to which this function library relates
* @return the stylesheet package
*/
public StylesheetPackage getStylesheetPackage() {
return pack;
}
/**
* 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
* @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 context
* @param reasons In the event that a function cannot be bound, this output parameter may be populated with one
* or more diagnostic messages indicating possible reasons why no function binding was possible.
* @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 = pack.getFunction(functionName);
if (fn == null) {
return null;
}
if (fn.isOverrideExtensionFunction() != this.overrideExtensionFunction) {
return null;
}
final UserFunctionCall fc = new UserFunctionCall();
fc.setFunctionName(functionName.getComponentName());
fc.setArguments(staticArgs);
fc.setFunction(fn);
if (env instanceof ExpressionContext) {
// compile-time binding of a static function call in XSLT
final PrincipalStylesheetModule psm = ((ExpressionContext) env).getStyleElement().getCompilation().getPrincipalStylesheetModule();
final ExpressionVisitor visitor = ExpressionVisitor.make(env);
psm.addFixupAction(() -> {
if (fc.getFunction() == null) {
Component target = psm.getComponent(fc.getSymbolicName());
UserFunction fn1 = (UserFunction) target.getActor();
if (fn1 != null) {
fc.allocateArgumentEvaluators();
fc.setStaticType(fn1.getResultType());
} else {
XPathException err = new XPathException("There is no available function named " + fc.getDisplayName() +
" with " + fc.getArity() + " arguments", "XPST0017");
err.setLocator(fc.getLocation());
throw err;
}
}
});
} else {
// must be a call within xsl:evaluate
}
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 {
return pack.getFunction(functionName);
}
/**
* 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, e.g. 31 for 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 pack.getFunction(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() {
return this;
}
}