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/*
 * $Header: /l/extreme/cvs/codes/XPP3/java/src/java/xpath/org/xmlpull/v1/builder/xpath/jaxen/SimpleVariableContext.java,v 1.1 2004/06/16 15:55:34 aslom Exp $
 * $Revision: 1.1 $
 * $Date: 2004/06/16 15:55:34 $
 *
 * ====================================================================
 *
 * Copyright (C) 2000-2002 bob mcwhirter & James Strachan.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions, and the disclaimer that follows 
 *    these conditions in the documentation and/or other materials 
 *    provided with the distribution.
 *
 * 3. The name "Jaxen" must not be used to endorse or promote products
 *    derived from this software without prior written permission.  For
 *    written permission, please contact [email protected].
 * 
 * 4. Products derived from this software may not be called "Jaxen", nor
 *    may "Jaxen" appear in their name, without prior written permission
 *    from the Jaxen Project Management ([email protected]).
 * 
 * In addition, we request (but do not require) that you include in the 
 * end-user documentation provided with the redistribution and/or in the 
 * software itself an acknowledgement equivalent to the following:
 *     "This product includes software developed by the
 *      Jaxen Project (http://www.jaxen.org/)."
 * Alternatively, the acknowledgment may be graphical using the logos 
 * available at http://www.jaxen.org/
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE Jaxen AUTHORS OR THE PROJECT
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * ====================================================================
 * This software consists of voluntary contributions made by many 
 * individuals on behalf of the Jaxen Project and was originally 
 * created by bob mcwhirter  and 
 * James Strachan .  For more information on the 
 * Jaxen Project, please see .
 * 
 * $Id: SimpleVariableContext.java,v 1.1 2004/06/16 15:55:34 aslom Exp $
 */


package org.xmlpull.v1.builder.xpath.jaxen;

import java.io.Serializable;
import java.util.Map;
import java.util.HashMap;

/** Simple default implementation for VariableContext.
 *
 *  
 *  This is a simple table-based key-lookup implementation
 *  for VariableContext which can be programmatically
 *  extended by setting additional variables.
 *  
 *
 *  @author bob mcwhirter
 */
public class SimpleVariableContext implements VariableContext, Serializable
{
    /** Table of variable bindings. */
    private Map variables;

    /** Construct.
     *
     *  
     *  Construct with an empty variable lookup table.
     *  
     */
    public SimpleVariableContext()
    {
        variables = new HashMap();
    }

    /** Set the value associated with a variable.
     *
     *  
     *  This method sets a variable that is 
     *  associated with any particular namespace.
     *  These variables appear such as $prefix:foo
     *  in an XPath expression.  Prefix to URI resolution
     *  is the responsibility of a NamespaceContext.
     *  Variables within a VariableContext are
     *  refered to purely based upon their namespace URI,
     *  if any.
     *  
     *
     *  @param namespaceURI The namespace URI of the variable.
     *  @param localName The local name of the variable
     *  @param value The value to be bound to the variable.
     */
    public void setVariableValue( String namespaceURI,
                                  String localName,
                                  Object value )
    {
        this.variables.put( new QualifiedName(namespaceURI, localName),
                            value );
    }

    /** Set the value associated with a variable.
     *
     *  
     *  This method sets a variable that is not
     *  associated with any particular namespace.
     *  These variables appear such as $foo
     *  in an XPath expression.
     *  
     *
     *  @param localName The local name of the variable
     *  @param value The value to be bound to the variable.
     */
    public void setVariableValue( String localName,
                                  Object value )
    {
        this.variables.put( new QualifiedName(null, localName), value );
    }

    public Object getVariableValue( String namespaceURI,
                                    String prefix,
                                    String localName )
        throws UnresolvableException
    {
        Object key = new QualifiedName( namespaceURI, localName );

        if ( this.variables.containsKey(key) )
        {
            return this.variables.get( key );
        }
        else
        {
            throw new UnresolvableException( "Variable {" + namespaceURI +
                                             "}" + prefix + ":" + localName );
        }
    }
}