/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


package org.apache.catalina.core;


import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Enumeration;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;

import jakarta.servlet.DispatcherType;
import jakarta.servlet.RequestDispatcher;
import jakarta.servlet.ServletContext;
import jakarta.servlet.ServletRequest;
import jakarta.servlet.ServletRequestWrapper;
import jakarta.servlet.http.HttpServletMapping;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletRequestWrapper;
import jakarta.servlet.http.HttpSession;
import jakarta.servlet.http.PushBuilder;

import org.apache.catalina.Context;
import org.apache.catalina.Globals;
import org.apache.catalina.Manager;
import org.apache.catalina.Session;
import org.apache.catalina.connector.RequestFacade;
import org.apache.catalina.util.ParameterMap;
import org.apache.catalina.util.RequestUtil;
import org.apache.catalina.util.URLEncoder;
import org.apache.tomcat.util.buf.B2CConverter;
import org.apache.tomcat.util.buf.MessageBytes;
import org.apache.tomcat.util.http.Parameters;
import org.apache.tomcat.util.res.StringManager;


Wrapper around a jakarta.servlet.http.HttpServletRequest
that transforms an application request object (which might be the original
one passed to a servlet, or might be based on the 2.3
jakarta.servlet.http.HttpServletRequestWrapper class)
back into an internal org.apache.catalina.HttpRequest.

WARNING:  Due to Java's lack of support for multiple
inheritance, all of the logic in ApplicationRequest is
duplicated in ApplicationHttpRequest.  Make sure that you
keep these two classes in synchronization when making changes!
Author:
Craig R. McClanahan, Remy Maucherat/**
 * Wrapper around a <code>jakarta.servlet.http.HttpServletRequest</code>
 * that transforms an application request object (which might be the original
 * one passed to a servlet, or might be based on the 2.3
 * <code>jakarta.servlet.http.HttpServletRequestWrapper</code> class)
 * back into an internal <code>org.apache.catalina.HttpRequest</code>.
 * <p>
 * <strong>WARNING</strong>:  Due to Java's lack of support for multiple
 * inheritance, all of the logic in <code>ApplicationRequest</code> is
 * duplicated in <code>ApplicationHttpRequest</code>.  Make sure that you
 * keep these two classes in synchronization when making changes!
 *
 * @author Craig R. McClanahan
 * @author Remy Maucherat
 */
class ApplicationHttpRequest extends HttpServletRequestWrapper {

    private static final StringManager sm = StringManager.getManager(ApplicationHttpRequest.class);

    
The set of attribute names that are special for request dispatchers.
/**
     * The set of attribute names that are special for request dispatchers.
     */
    protected static final String specials[] =
    { RequestDispatcher.INCLUDE_REQUEST_URI,
      RequestDispatcher.INCLUDE_CONTEXT_PATH,
      RequestDispatcher.INCLUDE_SERVLET_PATH,
      RequestDispatcher.INCLUDE_PATH_INFO,
      RequestDispatcher.INCLUDE_QUERY_STRING,
      RequestDispatcher.INCLUDE_MAPPING,
      RequestDispatcher.FORWARD_REQUEST_URI,
      RequestDispatcher.FORWARD_CONTEXT_PATH,
      RequestDispatcher.FORWARD_SERVLET_PATH,
      RequestDispatcher.FORWARD_PATH_INFO,
      RequestDispatcher.FORWARD_QUERY_STRING,
      RequestDispatcher.FORWARD_MAPPING};

    private static final int SPECIALS_FIRST_FORWARD_INDEX = 6;


    // ----------------------------------------------------------- Constructors


    
Construct a new wrapped request around the specified servlet request.
Params:
request – The servlet request being wrapped
context – The target context for the wrapped request
crossContext – true if the wrapped request will be a cross-context request, otherwise false/**
     * Construct a new wrapped request around the specified servlet request.
     *
     * @param request The servlet request being wrapped
     * @param context The target context for the wrapped request
     * @param crossContext {@code true} if the wrapped request will be a
     *                     cross-context request, otherwise {@code false}
     */
    public ApplicationHttpRequest(HttpServletRequest request, Context context,
                                  boolean crossContext) {

        super(request);
        this.context = context;
        this.crossContext = crossContext;
        setRequest(request);

    }


    // ----------------------------------------------------- Instance Variables


    
The context for this request.
/**
     * The context for this request.
     */
    protected final Context context;


    
The context path for this request.
/**
     * The context path for this request.
     */
    protected String contextPath = null;


    
If this request is cross context, since this changes session access
behavior.
/**
     * If this request is cross context, since this changes session access
     * behavior.
     */
    protected final boolean crossContext;


    
The current dispatcher type.
/**
     * The current dispatcher type.
     */
    protected DispatcherType dispatcherType = null;


    
The request parameters for this request.  This is initialized from the
wrapped request.
/**
     * The request parameters for this request.  This is initialized from the
     * wrapped request.
     */
    protected Map<String, String[]> parameters = null;


    
Have the parameters for this request already been parsed?
/**
     * Have the parameters for this request already been parsed?
     */
    private boolean parsedParams = false;


    
The path information for this request.
/**
     * The path information for this request.
     */
    protected String pathInfo = null;


    
The query parameters for the current request.
/**
     * The query parameters for the current request.
     */
    private String queryParamString = null;


    
The query string for this request.
/**
     * The query string for this request.
     */
    protected String queryString = null;


    
The current request dispatcher path.
/**
     * The current request dispatcher path.
     */
    protected Object requestDispatcherPath = null;


    
The request URI for this request.
/**
     * The request URI for this request.
     */
    protected String requestURI = null;


    
The servlet path for this request.
/**
     * The servlet path for this request.
     */
    protected String servletPath = null;


    
The mapping for this request.
/**
     * The mapping for this request.
     */
    private HttpServletMapping mapping = null;


    
The currently active session for this request.
/**
     * The currently active session for this request.
     */
    protected Session session = null;


    
Special attributes.
/**
     * Special attributes.
     */
    protected final Object[] specialAttributes = new Object[specials.length];


    // ------------------------------------------------- ServletRequest Methods

    @Override
    public ServletContext getServletContext() {
        if (context == null) {
            return null;
        }
        return context.getServletContext();
    }


    
Override the getAttribute() method of the wrapped request.
Params:
name – Name of the attribute to retrieve/**
     * Override the <code>getAttribute()</code> method of the wrapped request.
     *
     * @param name Name of the attribute to retrieve
     */
    @Override
    public Object getAttribute(String name) {

        if (name.equals(Globals.DISPATCHER_TYPE_ATTR)) {
            return dispatcherType;
        } else if (name.equals(Globals.DISPATCHER_REQUEST_PATH_ATTR)) {
            if ( requestDispatcherPath != null ){
                return requestDispatcherPath.toString();
            } else {
                return null;
            }
        }

        int pos = getSpecial(name);
        if (pos == -1) {
            return getRequest().getAttribute(name);
        } else {
            if ((specialAttributes[pos] == null) &&
                    (specialAttributes[SPECIALS_FIRST_FORWARD_INDEX] == null) &&
                    (pos >= SPECIALS_FIRST_FORWARD_INDEX)) {
                // If it's a forward special attribute, and null, it means this
                // is an include, so we check the wrapped request since
                // the request could have been forwarded before the include
                return getRequest().getAttribute(name);
            } else {
                return specialAttributes[pos];
            }
        }

    }


    
Override the getAttributeNames() method of the wrapped
request.
/**
     * Override the <code>getAttributeNames()</code> method of the wrapped
     * request.
     */
    @Override
    public Enumeration<String> getAttributeNames() {
        return new AttributeNamesEnumerator();
    }


    
Override the removeAttribute() method of the
wrapped request.
Params:
name – Name of the attribute to remove/**
     * Override the <code>removeAttribute()</code> method of the
     * wrapped request.
     *
     * @param name Name of the attribute to remove
     */
    @Override
    public void removeAttribute(String name) {

        if (!removeSpecial(name))
            getRequest().removeAttribute(name);

    }


    
Override the setAttribute() method of the
wrapped request.
Params:
name – Name of the attribute to set
value – Value of the attribute to set/**
     * Override the <code>setAttribute()</code> method of the
     * wrapped request.
     *
     * @param name Name of the attribute to set
     * @param value Value of the attribute to set
     */
    @Override
    public void setAttribute(String name, Object value) {

        if (name.equals(Globals.DISPATCHER_TYPE_ATTR)) {
            dispatcherType = (DispatcherType)value;
            return;
        } else if (name.equals(Globals.DISPATCHER_REQUEST_PATH_ATTR)) {
            requestDispatcherPath = value;
            return;
        }

        if (!setSpecial(name, value)) {
            getRequest().setAttribute(name, value);
        }

    }


    
Return a RequestDispatcher that wraps the resource at the specified
path, which may be interpreted as relative to the current request path.
Params:
path – Path of the resource to be wrapped/**
     * Return a RequestDispatcher that wraps the resource at the specified
     * path, which may be interpreted as relative to the current request path.
     *
     * @param path Path of the resource to be wrapped
     */
    @Override
    public RequestDispatcher getRequestDispatcher(String path) {

        if (context == null)
            return null;

        if (path == null) {
            return null;
        }

        int fragmentPos = path.indexOf('#');
        if (fragmentPos > -1) {
            context.getLogger().warn(sm.getString("applicationHttpRequest.fragmentInDispatchPath", path));
            path = path.substring(0, fragmentPos);
        }

        // If the path is already context-relative, just pass it through
        if (path.startsWith("/")) {
            return context.getServletContext().getRequestDispatcher(path);
        }

        // Convert a request-relative path to a context-relative one
        String servletPath =
            (String) getAttribute(RequestDispatcher.INCLUDE_SERVLET_PATH);
        if (servletPath == null)
            servletPath = getServletPath();

        // Add the path info, if there is any
        String pathInfo = getPathInfo();
        String requestPath = null;

        if (pathInfo == null) {
            requestPath = servletPath;
        } else {
            requestPath = servletPath + pathInfo;
        }

        int pos = requestPath.lastIndexOf('/');
        String relative = null;
        if (context.getDispatchersUseEncodedPaths()) {
            if (pos >= 0) {
                relative = URLEncoder.DEFAULT.encode(
                        requestPath.substring(0, pos + 1), StandardCharsets.UTF_8) + path;
            } else {
                relative = URLEncoder.DEFAULT.encode(requestPath, StandardCharsets.UTF_8) + path;
            }
        } else {
            if (pos >= 0) {
                relative = requestPath.substring(0, pos + 1) + path;
            } else {
                relative = requestPath + path;
            }
        }

        return context.getServletContext().getRequestDispatcher(relative);

    }


    
Override the getDispatcherType() method of the wrapped request.
/**
     * Override the getDispatcherType() method of the wrapped request.
     *
     */
    @Override
    public DispatcherType getDispatcherType() {
        return dispatcherType;
    }


    // --------------------------------------------- HttpServletRequest Methods


    
Override the getContextPath() method of the wrapped
request.
/**
     * Override the <code>getContextPath()</code> method of the wrapped
     * request.
     */
    @Override
    public String getContextPath() {
        return this.contextPath;
    }


    
Override the getParameter() method of the wrapped request.
Params:
name – Name of the requested parameter/**
     * Override the <code>getParameter()</code> method of the wrapped request.
     *
     * @param name Name of the requested parameter
     */
    @Override
    public String getParameter(String name) {
        parseParameters();

        String[] value = parameters.get(name);
        if (value == null) {
            return null;
        }
        return value[0];
    }


    
Override the getParameterMap() method of the
wrapped request.
/**
     * Override the <code>getParameterMap()</code> method of the
     * wrapped request.
     */
    @Override
    public Map<String, String[]> getParameterMap() {
        parseParameters();
        return parameters;
    }


    
Override the getParameterNames() method of the
wrapped request.
/**
     * Override the <code>getParameterNames()</code> method of the
     * wrapped request.
     */
    @Override
    public Enumeration<String> getParameterNames() {
        parseParameters();
        return Collections.enumeration(parameters.keySet());
    }


    
Override the getParameterValues() method of the
wrapped request.
Params:
name – Name of the requested parameter/**
     * Override the <code>getParameterValues()</code> method of the
     * wrapped request.
     *
     * @param name Name of the requested parameter
     */
    @Override
    public String[] getParameterValues(String name) {
        parseParameters();
        return parameters.get(name);
    }


    
Override the getPathInfo() method of the wrapped request.
/**
     * Override the <code>getPathInfo()</code> method of the wrapped request.
     */
    @Override
    public String getPathInfo() {
        return this.pathInfo;
    }


    
Override the getPathTranslated() method of the wrapped
request.
/**
     * Override the <code>getPathTranslated()</code> method of the wrapped
     * request.
     */
    @Override
    public String getPathTranslated() {
        if (getPathInfo() == null || getServletContext() == null) {
            return null;
        }

        return getServletContext().getRealPath(getPathInfo());
    }


    
Override the getQueryString() method of the wrapped
request.
/**
     * Override the <code>getQueryString()</code> method of the wrapped
     * request.
     */
    @Override
    public String getQueryString() {
        return this.queryString;
    }


    
Override the getRequestURI() method of the wrapped
request.
/**
     * Override the <code>getRequestURI()</code> method of the wrapped
     * request.
     */
    @Override
    public String getRequestURI() {
        return this.requestURI;
    }


    
Override the getRequestURL() method of the wrapped
request.
/**
     * Override the <code>getRequestURL()</code> method of the wrapped
     * request.
     */
    @Override
    public StringBuffer getRequestURL() {
        return RequestUtil.getRequestURL(this);
    }


    
Override the getServletPath() method of the wrapped
request.
/**
     * Override the <code>getServletPath()</code> method of the wrapped
     * request.
     */
    @Override
    public String getServletPath() {
        return this.servletPath;
    }


    @Override
    public HttpServletMapping getHttpServletMapping() {
        return mapping;
    }


    
Return the session associated with this Request, creating one
if necessary.
/**
     * Return the session associated with this Request, creating one
     * if necessary.
     */
    @Override
    public HttpSession getSession() {
        return getSession(true);
    }


    
Return the session associated with this Request, creating one
if necessary and requested.
Params:
create – Create a new session if one does not exist/**
     * Return the session associated with this Request, creating one
     * if necessary and requested.
     *
     * @param create Create a new session if one does not exist
     */
    @Override
    public HttpSession getSession(boolean create) {

        if (crossContext) {

            // There cannot be a session if no context has been assigned yet
            if (context == null)
                return null;

            // Return the current session if it exists and is valid
            if (session != null && session.isValid()) {
                return session.getSession();
            }

            HttpSession other = super.getSession(false);
            if (create && (other == null)) {
                // First create a session in the first context: the problem is
                // that the top level request is the only one which can
                // create the cookie safely
                other = super.getSession(true);
            }
            if (other != null) {
                Session localSession = null;
                try {
                    localSession =
                        context.getManager().findSession(other.getId());
                    if (localSession != null && !localSession.isValid()) {
                        localSession = null;
                    }
                } catch (IOException e) {
                    // Ignore
                }
                if (localSession == null && create) {
                    localSession =
                        context.getManager().createSession(other.getId());
                }
                if (localSession != null) {
                    localSession.access();
                    session = localSession;
                    return session.getSession();
                }
            }
            return null;

        } else {
            return super.getSession(create);
        }

    }


    
Returns true if the request specifies a JSESSIONID that is valid within
the context of this ApplicationHttpRequest, false otherwise.
Returns:
true if the request specifies a JSESSIONID that is valid within
the context of this ApplicationHttpRequest, false otherwise./**
     * Returns true if the request specifies a JSESSIONID that is valid within
     * the context of this ApplicationHttpRequest, false otherwise.
     *
     * @return true if the request specifies a JSESSIONID that is valid within
     * the context of this ApplicationHttpRequest, false otherwise.
     */
    @Override
    public boolean isRequestedSessionIdValid() {

        if (crossContext) {

            String requestedSessionId = getRequestedSessionId();
            if (requestedSessionId == null)
                return false;
            if (context == null)
                return false;
            Manager manager = context.getManager();
            if (manager == null)
                return false;
            Session session = null;
            try {
                session = manager.findSession(requestedSessionId);
            } catch (IOException e) {
                // Ignore
            }
            if ((session != null) && session.isValid()) {
                return true;
            } else {
                return false;
            }

        } else {
            return super.isRequestedSessionIdValid();
        }
    }


    @Override
    public PushBuilder newPushBuilder() {
        ServletRequest current = getRequest();
        while (current instanceof ServletRequestWrapper) {
            current = ((ServletRequestWrapper) current).getRequest();
        }
        if (current instanceof RequestFacade) {
            return ((RequestFacade) current).newPushBuilder(this);
        } else {
            return null;
        }
    }


    // -------------------------------------------------------- Package Methods

    
Recycle this request
/**
     * Recycle this request
     */
    public void recycle() {
        if (session != null) {
            session.endAccess();
        }
    }


    
Set the context path for this request.
Params:
contextPath – The new context path/**
     * Set the context path for this request.
     *
     * @param contextPath The new context path
     */
    void setContextPath(String contextPath) {

        this.contextPath = contextPath;

    }


    
Set the path information for this request.
Params:
pathInfo – The new path info/**
     * Set the path information for this request.
     *
     * @param pathInfo The new path info
     */
    void setPathInfo(String pathInfo) {

        this.pathInfo = pathInfo;

    }


    
Set the query string for this request.
Params:
queryString – The new query string/**
     * Set the query string for this request.
     *
     * @param queryString The new query string
     */
    void setQueryString(String queryString) {

        this.queryString = queryString;

    }


    
Set the request that we are wrapping.
Params:
request – The new wrapped request/**
     * Set the request that we are wrapping.
     *
     * @param request The new wrapped request
     */
    void setRequest(HttpServletRequest request) {

        super.setRequest(request);

        // Initialize the attributes for this request
        dispatcherType = (DispatcherType)request.getAttribute(Globals.DISPATCHER_TYPE_ATTR);
        requestDispatcherPath =
            request.getAttribute(Globals.DISPATCHER_REQUEST_PATH_ATTR);

        // Initialize the path elements for this request
        contextPath = request.getContextPath();
        pathInfo = request.getPathInfo();
        queryString = request.getQueryString();
        requestURI = request.getRequestURI();
        servletPath = request.getServletPath();
        mapping = request.getHttpServletMapping();
    }


    
Set the request URI for this request.
Params:
requestURI – The new request URI/**
     * Set the request URI for this request.
     *
     * @param requestURI The new request URI
     */
    void setRequestURI(String requestURI) {

        this.requestURI = requestURI;

    }


    
Set the servlet path for this request.
Params:
servletPath – The new servlet path/**
     * Set the servlet path for this request.
     *
     * @param servletPath The new servlet path
     */
    void setServletPath(String servletPath) {

        this.servletPath = servletPath;

    }


    
Parses the parameters of this request.
If parameters are present in both the query string and the request
content, they are merged.
/**
     * Parses the parameters of this request.
     *
     * If parameters are present in both the query string and the request
     * content, they are merged.
     */
    void parseParameters() {

        if (parsedParams) {
            return;
        }

        parameters = new ParameterMap<>();
        parameters.putAll(getRequest().getParameterMap());
        mergeParameters();
        ((ParameterMap<String,String[]>) parameters).setLocked(true);
        parsedParams = true;
    }


    
Save query parameters for this request.
Params:
queryString – The query string containing parameters for this
                   request/**
     * Save query parameters for this request.
     *
     * @param queryString The query string containing parameters for this
     *                    request
     */
    void setQueryParams(String queryString) {
        this.queryParamString = queryString;
    }


    void setMapping(HttpServletMapping mapping) {
        this.mapping = mapping;
    }


    // ------------------------------------------------------ Protected Methods

    
Is this attribute name one of the special ones that is added only for
included servlets?
Params:
name – Attribute name to be tested/**
     * Is this attribute name one of the special ones that is added only for
     * included servlets?
     *
     * @param name Attribute name to be tested
     */
    protected boolean isSpecial(String name) {

        for (String special : specials) {
            if (special.equals(name))
                return true;
        }
        return false;

    }


    
Get a special attribute.
Returns:
the special attribute pos, or -1 if it is not a special
        attribute/**
     * Get a special attribute.
     *
     * @return the special attribute pos, or -1 if it is not a special
     *         attribute
     */
    protected int getSpecial(String name) {
        for (int i = 0; i < specials.length; i++) {
            if (specials[i].equals(name)) {
                return i;
            }
        }
        return -1;
    }


    
Set a special attribute.
Returns:
true if the attribute was a special attribute, false otherwise/**
     * Set a special attribute.
     *
     * @return true if the attribute was a special attribute, false otherwise
     */
    protected boolean setSpecial(String name, Object value) {
        for (int i = 0; i < specials.length; i++) {
            if (specials[i].equals(name)) {
                specialAttributes[i] = value;
                return true;
            }
        }
        return false;
    }


    
Remove a special attribute.
Returns:
true if the attribute was a special attribute, false otherwise/**
     * Remove a special attribute.
     *
     * @return true if the attribute was a special attribute, false otherwise
     */
    protected boolean removeSpecial(String name) {
        for (int i = 0; i < specials.length; i++) {
            if (specials[i].equals(name)) {
                specialAttributes[i] = null;
                return true;
            }
        }
        return false;
    }


    
Merge the two sets of parameter values into a single String array.
Params:
values1 – First set of values
values2 – Second set of values/**
     * Merge the two sets of parameter values into a single String array.
     *
     * @param values1 First set of values
     * @param values2 Second set of values
     */
    private String[] mergeValues(String[] values1, String[] values2) {

        List<Object> results = new ArrayList<>();

        if (values1 == null) {
            // Skip - nothing to merge
        } else {
            results.addAll(Arrays.asList(values1));
        }

        if (values2 == null) {
            // Skip - nothing to merge
        } else {
            results.addAll(Arrays.asList(values2));
        }

        String values[] = new String[results.size()];
        return results.toArray(values);
    }


    // ------------------------------------------------------ Private Methods


    
Merge the parameters from the saved query parameter string (if any), and
the parameters already present on this request (if any), such that the
parameter values from the query string show up first if there are
duplicate parameter names.
/**
     * Merge the parameters from the saved query parameter string (if any), and
     * the parameters already present on this request (if any), such that the
     * parameter values from the query string show up first if there are
     * duplicate parameter names.
     */
    private void mergeParameters() {

        if ((queryParamString == null) || (queryParamString.length() < 1))
            return;

        // Parse the query string from the dispatch target
        Parameters paramParser = new Parameters();
        MessageBytes queryMB = MessageBytes.newInstance();
        queryMB.setString(queryParamString);

        // TODO
        // - Should only use body encoding if useBodyEncodingForURI is true
        // - Otherwise, should use URIEncoding
        // - The problem is that the connector is not available...
        // - To add to the fun, the URI default changed in Servlet 4.0 to UTF-8

        String encoding = getCharacterEncoding();
        Charset charset = null;
        if (encoding != null) {
            try {
                charset = B2CConverter.getCharset(encoding);
                queryMB.setCharset(charset);
            } catch (UnsupportedEncodingException e) {
                // Fall-back to default (ISO-8859-1)
                charset = StandardCharsets.ISO_8859_1;
            }
        }

        paramParser.setQuery(queryMB);
        paramParser.setQueryStringCharset(charset);
        paramParser.handleQueryParameters();

        // Insert the additional parameters from the dispatch target
        Enumeration<String> dispParamNames = paramParser.getParameterNames();
        while (dispParamNames.hasMoreElements()) {
            String dispParamName = dispParamNames.nextElement();
            String[] dispParamValues = paramParser.getParameterValues(dispParamName);
            String[] originalValues = parameters.get(dispParamName);
            if (originalValues == null) {
                parameters.put(dispParamName, dispParamValues);
                continue;
            }
            parameters.put(dispParamName, mergeValues(dispParamValues, originalValues));
        }
    }


    // ----------------------------------- AttributeNamesEnumerator Inner Class


    
Utility class used to expose the special attributes as being available
as request attributes.
/**
     * Utility class used to expose the special attributes as being available
     * as request attributes.
     */
    protected class AttributeNamesEnumerator implements Enumeration<String> {

        protected int pos = -1;
        protected final int last;
        protected final Enumeration<String> parentEnumeration;
        protected String next = null;

        public AttributeNamesEnumerator() {
            int last = -1;
            parentEnumeration = getRequest().getAttributeNames();
            for (int i = specialAttributes.length - 1; i >= 0; i--) {
                if (getAttribute(specials[i]) != null) {
                    last = i;
                    break;
                }
            }
            this.last = last;
        }

        @Override
        public boolean hasMoreElements() {
            return ((pos != last) || (next != null)
                    || ((next = findNext()) != null));
        }

        @Override
        public String nextElement() {
            if (pos != last) {
                for (int i = pos + 1; i <= last; i++) {
                    if (getAttribute(specials[i]) != null) {
                        pos = i;
                        return specials[i];
                    }
                }
            }
            String result = next;
            if (next != null) {
                next = findNext();
            } else {
                throw new NoSuchElementException();
            }
            return result;
        }

        protected String findNext() {
            String result = null;
            while ((result == null) && (parentEnumeration.hasMoreElements())) {
                String current = parentEnumeration.nextElement();
                if (!isSpecial(current)) {
                    result = current;
                }
            }
            return result;
        }

    }


}