FunctionLibraryList.java

package client.net.sf.saxon.ce.functions;

import client.net.sf.saxon.ce.expr.Container;
import client.net.sf.saxon.ce.expr.Expression;
import client.net.sf.saxon.ce.expr.StaticContext;
import client.net.sf.saxon.ce.om.StructuredQName;
import client.net.sf.saxon.ce.trans.XPathException;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

/**
 * 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 {

    public List<FunctionLibrary> 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 system function with a given name and arity is available, and return its signature. This supports
     * the function-available() function in XSLT. This method may be called either at compile time
     * or at run time.
     * @param functionName the name of the function
     * @param arity The number of arguments. This is set to -1 in the case of the single-argument function-available() function
     * @return if a function of this name and arity is available for calling, then the type signature of the
     * function, as an array of sequence types in which the zeroth entry represents the return type; otherwise null
     */

    public boolean hasFunctionSignature(StructuredQName functionName, int arity) {
        for (Iterator it=libraryList.iterator(); it.hasNext();) {
            FunctionLibrary lib = (FunctionLibrary)it.next();
            boolean b = lib.hasFunctionSignature(functionName, arity);
            if (b) {
                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
     * @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 env
     * @param container
     * @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.
     * @throws client.net.sf.saxon.ce.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, Expression[] staticArgs, StaticContext env, Container container)
            throws XPathException {
        for (FunctionLibrary lib : libraryList) {
            Expression func = lib.bind(functionName, staticArgs, env, container);
            if (func != null) {
                return func;
            }
        }
        return null;
    }

 
    /**
     * 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<FunctionLibrary> getLibraryList() {
        return libraryList;
    }

}
// 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.