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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.query;
import net.sf.saxon.expr.Expression;
import net.sf.saxon.expr.StaticContext;
import net.sf.saxon.expr.parser.RetainedStaticContext;
import net.sf.saxon.functions.FunctionLibrary;
import net.sf.saxon.om.Function;
import net.sf.saxon.om.StructuredQName;
import net.sf.saxon.trans.SymbolicName;
import net.sf.saxon.trans.XPathException;
import java.util.HashSet;
import java.util.List;
/**
* This implementation of FunctionLibrary contains all the functions imported into a Query Module.
* It is implemented as a view of the "global" XQueryFunctionLibrary for the whole query, selecting
* only those functions that are in an imported namespace.
*/
public class ImportedFunctionLibrary implements FunctionLibrary, XQueryFunctionBinder {
private transient QueryModule importingModule;
private final XQueryFunctionLibrary baseLibrary;
private final HashSet namespaces = new HashSet<>(5);
/**
* Create an imported function library
*
* @param importingModule the module importing the library
* @param baseLibrary the function library of which this is a subset view
*/
public ImportedFunctionLibrary(QueryModule importingModule, XQueryFunctionLibrary baseLibrary) {
this.importingModule = importingModule;
this.baseLibrary = baseLibrary;
}
/**
* Add an imported namespace
*
* @param namespace the imported namespace
*/
public void addImportedNamespace(String namespace) {
namespaces.add(namespace);
}
/**
* 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 symbolicName the name of the function to be bound
* @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 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 function to be called, if one is found;
* null if no function was found matching the required name and arity.
*/
/*@Nullable*/
@Override
public Expression bind(/*@NotNull*/ SymbolicName.F symbolicName, Expression[] staticArgs, StaticContext env, List reasons) {
final StructuredQName functionName = symbolicName.getComponentName();
final String uri = functionName.getURI();
RetainedStaticContext rsc = new RetainedStaticContext(env);
for (Expression arg : staticArgs) {
if (arg.getLocalRetainedStaticContext() == null) {
arg.setRetainedStaticContext(rsc);
}
}
if (namespaces.contains(uri)) {
return baseLibrary.bind(symbolicName, staticArgs, env, reasons);
} else {
return null;
}
}
/**
* Get the function declaration corresponding to a given function name and arity
*
* @return the XQueryFunction if there is one, or null if not.
*/
/*@Nullable*/
@Override
public XQueryFunction getDeclaration(/*@NotNull*/ StructuredQName functionName, int staticArgs) {
String uri = functionName.getURI();
if (namespaces.contains(uri)) {
return baseLibrary.getDeclaration(functionName, staticArgs);
} else {
return 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.
*/
/*@NotNull*/
@Override
public FunctionLibrary copy() {
ImportedFunctionLibrary lib = new ImportedFunctionLibrary(importingModule, baseLibrary);
for (String ns : namespaces) {
lib.addImportedNamespace(ns);
}
return lib;
}
/**
* Set the module that imports this function libary
*
* @param importingModule the importing module
*/
public void setImportingModule(QueryModule importingModule) {
this.importingModule = importingModule;
}
/**
* 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 {
if (namespaces.contains(functionName.getComponentName().getURI())) {
return baseLibrary.getFunctionItem(functionName, staticContext);
} else {
return null;
}
}
/**
* 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 namespaces.contains(functionName.getComponentName().getURI())
&& baseLibrary.isAvailable(functionName, languageLevel);
}
}