test12/src/main/java/org/apache/myfaces/test/el/FacesImplicitObjectELResolver.java

/*
 * 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.myfaces.test.el;

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

import javax.el.ELContext;
import javax.el.PropertyNotFoundException;
import javax.el.PropertyNotWritableException;
import javax.faces.component.UIViewRoot;
import javax.faces.context.ExternalContext;
import javax.faces.context.FacesContext;

/**
 * <p><code>ELResolver</code> implementation that accesses implicit objects
 * in the current request context.  See the JSF 1.2 Specification, section
 * 5.6.2.1, for requirements implemented by this class.</p>
 *
 * @since 1.0.4
 */
public class FacesImplicitObjectELResolver extends AbstractELResolver {
    

    /**
     * <p>The names of all implicit objects recognized by this resolver.</p>
     */
    private static final String[] NAMES =
    { "application", "applicationScope", "cookie", "facesContext",
      "header", "headerValues", "initParam", "param", "paramValues",
      "request", "requestScope", "session", "sessionScope", "view" };


    /**
     * <p>The property types corresponding to the implicit object names.</p>
     */
    private static final Class[] TYPES =
    { Object.class, Map.class, Map.class, FacesContext.class,
      Map.class, Map.class, Map.class, Map.class, Map.class,
      Object.class, Map.class, Object.class, Map.class, UIViewRoot.class };


    /**
     * <p>The settable value types corresponding to the implicit
     * object names.</p>
     */
    private static final Class[] VALUES =
    { null, Object.class, null, null,
      null, null, null, null, null,
      null, Object.class, null, Object.class, null };


    /**
     * <p>Return the most general type this resolver accepts for the
     * <code>property</code> argument.</p>
     */
    public Class getCommonPropertyType(ELContext context, Object base) {

        if (base != null) {
            return null;
        } else {
            return String.class;
        }

    }


    /**
     * <p>Return an <code>Iterator</code> over the attributes that this
     * resolver knows how to deal with.</p>
     *
     * @param context <code>ELContext</code> for evaluating this value
     * @param base Base object against which this evaluation occurs
     */
    public Iterator getFeatureDescriptors(ELContext context, Object base) {

        if (base != null) {
            return null;
        }

        // Create the variables we will need
        FacesContext fcontext = (FacesContext) context.getContext(FacesContext.class);
        List descriptors = new ArrayList();

        // Add feature descriptors for each implicit object
        for (int i = 0; i < NAMES.length; i++) {
            descriptors.add(descriptor(NAMES[i], NAMES[i], NAMES[i],
                                   false, false, true, TYPES[i], true));
        }

        // Return the accumulated descriptors
        return descriptors.iterator();

    }



    /**
     * <p>Return the Java type of the specified property.</p>
     *
     * @param context <code>ELContext</code> for evaluating this value
     * @param base Base object against which this evaluation occurs
     *  (must be null because we are evaluating a top level variable)
     * @param property Property name to be accessed
     */
    public Class getType(ELContext context, Object base, Object property) {

        if (base != null) {
            return null;
        }
        if (property == null) {
            throw new PropertyNotFoundException("No property specified");
        }
        String name = property.toString();
        for (int i = 0; i < NAMES.length; i++) {
            if (name.equals(NAMES[i])) {
                context.setPropertyResolved(true);
                return VALUES[i];
            }
        }
        return null;

    }


    /**
     * <p>Return an existing scoped object for the specified name (if any);
     * otherwise, return <code>null</code>.</p>
     *
     * @param context <code>ELContext</code> for evaluating this value
     * @param base Base object against which this evaluation occurs
     *  (must be null because we are evaluating a top level variable)
     * @param property Property name to be accessed
     */
    public Object getValue(ELContext context, Object base, Object property) {

        if (base != null) {
            return null;
        }
        if (property == null) {
            throw new PropertyNotFoundException("No property specified");
        }

        FacesContext fcontext = (FacesContext) context.getContext(FacesContext.class);
        ExternalContext econtext = fcontext.getExternalContext();
        String name = property.toString();

        if (name.equals("application")) {
            context.setPropertyResolved(true);
            return econtext.getContext();
        } else if (name.equals("applicationScope")) {
            context.setPropertyResolved(true);
            return econtext.getApplicationMap();
        } else if (name.equals("cookie")) {
            context.setPropertyResolved(true);
            return econtext.getRequestCookieMap();
        } else if (name.equals("facesContext")) {
            context.setPropertyResolved(true);
            return fcontext;
        } else if (name.equals("header")) {
            context.setPropertyResolved(true);
            return econtext.getRequestHeaderMap();
        } else if (name.equals("headerValues")) {
            context.setPropertyResolved(true);
            return econtext.getRequestHeaderValuesMap();
        } else if (name.equals("initParam")) {
            context.setPropertyResolved(true);
            return econtext.getInitParameterMap();
        } else if (name.equals("param")) {
            context.setPropertyResolved(true);
            return econtext.getRequestParameterMap();
        } else if (name.equals("paramValues")) {
            context.setPropertyResolved(true);
            return econtext.getRequestParameterValuesMap();
        } else if (name.equals("request")) {
            context.setPropertyResolved(true);
            return econtext.getRequest();
        } else if (name.equals("requestScope")) {
            context.setPropertyResolved(true);
            return econtext.getRequestMap();
        } else if (name.equals("session")) {
            context.setPropertyResolved(true);
            return econtext.getSession(true);
        } else if (name.equals("sessionScope")) {
            context.setPropertyResolved(true);
            return econtext.getSessionMap();
        } else if (name.equals("view")) {
            context.setPropertyResolved(true);
            return fcontext.getViewRoot();
        }

        return null;

    }


    /**
     * <p>Return <code>true</code> if the specified property is read only.</p>
     *
     * @param context <code>ELContext</code> for evaluating this value
     * @param base Base object against which this evaluation occurs
     *  (must be null because we are evaluating a top level variable)
     * @param property Property name to be accessed
     */
    public boolean isReadOnly(ELContext context, Object base, Object property) {

        if (base != null) {
            return false;
        }
        if (property == null) {
            throw new PropertyNotFoundException("No property specified");
        }
        String name = property.toString();
        for (int i = 0; i < NAMES.length; i++) {
            if (name.equals(NAMES[i])) {
                context.setPropertyResolved(true);
                return true;
            }
        }
        return false;

    }



    /**
     * <p>Set the value of a scoped object for the specified name.</p>
     *
     * @param context <code>ELContext</code> for evaluating this value
     * @param base Base object against which this evaluation occurs
     *  (must be null because we are evaluating a top level variable)
     * @param property Property name to be accessed
     * @param value New value to be set
     */
    public void setValue(ELContext context, Object base, Object property, Object value) {

        if (base != null) {
            return;
        }
        if (property == null) {
            throw new PropertyNotFoundException("No property specified");
        }

        String name = property.toString();
        for (int i = 0; i < NAMES.length; i++) {
            if (name.equals(NAMES[i])) {
                context.setPropertyResolved(true);
                throw new PropertyNotWritableException(name);
            }
        }

    }


}