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/*
 * eXist-db Open Source Native XML Database
 * Copyright (C) 2001 The eXist-db Authors
 *
 * [email protected]
 * http://www.exist-db.org
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */
package org.exist.xquery;

import org.exist.dom.QName;
import org.exist.source.Source;
import org.exist.storage.DBBroker;

import java.util.Collection;
import java.util.Map;

/**
 * An external library module implemented in XQuery and loaded
 * through the "import module" directive.
 * 
 * @author Wolfgang Meier
 */
public interface ExternalModule extends Module {

    public void setNamespace(String prefix, String namespace);

    public void setDescription(String desc);

    public void addMetadata(String key, String value);

    public Map getMetadata();

    /**
     * Declare a new function. Called by the XQuery compiler
     * when parsing a library module for every function declaration.
     * 
     * @param func the function to add
     */
    public void declareFunction(UserDefinedFunction func);

    /**
     * Try to find the function identified by qname. Returns null
     * if the function is undefined.
     * 
     * @param qname the name of the function to look for
     * @param arity arity of the function to look for
     * @param callerContext context of the caller - needed to check if
     *                      found function should be visible
     * @throws XPathException in case of a dynamic error
     * @return the function found
     */
    public UserDefinedFunction getFunction(QName qname, int arity, XQueryContext callerContext) throws XPathException;

    public void declareVariable(QName qname, VariableDeclaration decl) throws XPathException;

    /**
     * Analyze declared variables. Needs to be called when the module was imported dynamically.
     *
     * @throws XPathException in case of static errors
     */
    public void analyzeGlobalVars() throws XPathException;

    public Collection getVariableDeclarations();

    /**
     * Get the source object this module has been read from.
     *
     * This is required for query access control.
     * @return The source object this module has been read from.
     */
    public Source getSource();

    /**
     * Set the source object this module has been read from.
     * 
     * This is required to check the validity of a compiled expression.
     * @param source the source instance
     */
    public void setSource(Source source);

    public XQueryContext getContext();

    /**
     * Set the XQueryContext of this module. This will be a sub-context
     * of the main context as parts of the static context are shared. 
     * 
     * @param context the context to set
     */
    public void setContext(XQueryContext context);

    /**
     * Is this module still valid or should it be reloaded from its source?
     *
     * @param broker the broker to use for checking
     * @return true if module should be reloaded
     */
    public boolean moduleIsValid(DBBroker broker);

    /**
     * Returns the root expression associated with this context.
     *
     * @return  root expression
     */
    public Expression getRootExpression();
}