net.sf.saxon.functions.FunctionLibraryList Maven / Gradle / Ivy
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// Copyright (c) 2018-2023 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.Expression;
import net.sf.saxon.expr.StaticContext;
import net.sf.saxon.expr.UserFunctionCall;
import net.sf.saxon.lib.Feature;
import net.sf.saxon.lib.Logger;
import net.sf.saxon.om.FunctionItem;
import net.sf.saxon.om.StructuredQName;
import net.sf.saxon.query.XQueryFunction;
import net.sf.saxon.query.XQueryFunctionBinder;
import net.sf.saxon.trans.SymbolicName;
import net.sf.saxon.trans.XPathException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
/**
* A FunctionLibraryList is a list of FunctionLibraries. It is also a FunctionLibrary in its own right.
* When required, it searches the list of FunctionLibraries to find the required function.
*/
public class FunctionLibraryList implements FunctionLibrary, XQueryFunctionBinder {
public List libraryList = new ArrayList<>(8);
public FunctionLibraryList() {
}
/**
* Add a new FunctionLibrary to the list of FunctionLibraries in this FunctionLibraryList. Note
* that libraries are searched in the order they are added to the list.
*
* @param lib A function library to be added to the list of function libraries to be searched.
* @return the position of the library in the list
*/
public int addFunctionLibrary(FunctionLibrary lib) {
libraryList.add(lib);
return libraryList.size() - 1;
}
/**
* Get the n'th function library in the list
*/
public FunctionLibrary get(int n) {
return libraryList.get(n);
}
/**
* 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
*/
@Override
public FunctionItem getFunctionItem(SymbolicName.F functionName, StaticContext staticContext) throws XPathException {
for (FunctionLibrary lib : libraryList) {
FunctionItem fi = lib.getFunctionItem(functionName, staticContext);
if (fi != null) {
return fi;
}
}
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) {
for (FunctionLibrary lib : libraryList) {
if (lib.isAvailable(functionName, languageLevel)) {
return true;
}
}
return false;
}
/**
* 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 name of the function
* @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.
* @param keywords May be null if no keywords are used in the function call. Otherwise, a map identifying the
* keywords appearing in the function call, and the 0-based position at which they appeared.
* @param env The static 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,
Map keywords, StaticContext env, List reasons)
throws XPathException {
boolean debug = env.getConfiguration().getBooleanProperty(Feature.TRACE_EXTERNAL_FUNCTIONS);
Logger err = env.getConfiguration().getLogger();
if (debug) {
err.info("Looking for function " + functionName.getComponentName().getEQName() + "#" + functionName.getArity());
}
for (FunctionLibrary lib : libraryList) {
if (debug) {
err.info("Trying " + lib.getClass().getName());
}
Expression func = lib.bind(functionName, staticArgs, keywords, env, reasons);
if (func != null) {
return func;
}
}
if (debug) {
err.info("Function " + functionName.getComponentName().getEQName() + " not found!");
}
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.
*/
@Override
public XQueryFunction getDeclaration(StructuredQName functionName, int staticArgs) {
for (FunctionLibrary lib : libraryList) {
if (lib instanceof XQueryFunctionBinder) {
XQueryFunction func = ((XQueryFunctionBinder) lib).getDeclaration(functionName, staticArgs);
if (func != null) {
return func;
}
}
}
return null;
}
/**
* Bind a function call using this function library, in the situation where
* it was not possible to bind it earlier, typically because it was encountered as a forwards
* reference.
*
* @param call The unbound function call, which will include a non-null UnboundFunctionCallDetails
* @param reasons a list which can be populated with messages indicating why binding failed
* @return true if the function call is now bound; false if it remains unbound.
*/
@Override
public boolean bindUnboundFunctionCall(UserFunctionCall call, List reasons) {
for (FunctionLibrary lib : libraryList) {
if (lib instanceof XQueryFunctionBinder) {
boolean found = ((XQueryFunctionBinder) lib).bindUnboundFunctionCall(call, reasons);
if (found) {
return true;
}
}
}
return false;
}
/**
* Get the list of contained FunctionLibraries. This method allows the caller to modify
* the library list, for example by adding a new FunctionLibrary at a chosen position,
* by removing a library from the list, or by changing the order of libraries in the list.
* Note that such changes may violate rules in the
* language specifications, or assumptions made within the product.
*
* @return a list whose members are of class FunctionLibrary
*/
public List getLibraryList() {
return libraryList;
}
/**
* 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() {
FunctionLibraryList fll = new FunctionLibraryList();
fll.libraryList = emptyFunctionLibraryList(libraryList.size());
for (int i = 0; i < libraryList.size(); i++) {
fll.libraryList.add(libraryList.get(i).copy());
}
return fll;
}
private static ArrayList emptyFunctionLibraryList(int allocated) {
// Separate method for C# type inference
return new ArrayList<>(allocated);
}
}
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