non-releases/trunk_before_flattening/src/java/org/apache/cocoon/environment/ObjectModelHelper.java

/*
 * Copyright 1999-2004 The Apache Software Foundation.
 * 
 * Licensed 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.cocoon.environment;

import java.util.Map;

/**
 * A set of constants and methods to access the content of the object model.
 * <p>
 * The object model is a <code>Map</code> used to pass information about the
 * calling environment to the sitemap and its components (matchers, actions,
 * transformers, etc).
 * <p>
 * This class provides accessors only for the objects in the object model that are
 * common to every environment and which can thus be used safely. Some environments
 * provide additional objects, but they are not described here and accessing them
 * should be done in due cause since this ties the application to that particular
 * environment.
 *
 * @version $Id$
 */
public final class ObjectModelHelper {

    /** Key for the environment {@link Request} in the object model. */
    public final static String REQUEST_OBJECT  = "request";

    /** Key for the environment {@link Response} in the object model. */
    public final static String RESPONSE_OBJECT = "response";

    /** Key for the environment {@link Context} in the object model. */
    public final static String CONTEXT_OBJECT  = "context";

    /** Key for the expiration value (Long) in the object model. */
    public final static String EXPIRES_OBJECT  = "expires";
    
    /** Key for the throwable object, only available within a &lt;map:handle-errors>. */
    public final static String THROWABLE_OBJECT = "throwable";

    /**
     * Key for a {@link Map} containing information from
     * a parent request provided to a sub-request (internal processing)
     */
    public final static String PARENT_CONTEXT = "parent-context";


    private ObjectModelHelper() {
        // Forbid instantiation
    }

    public static final Request getRequest(Map objectModel) {
        return (Request)objectModel.get(REQUEST_OBJECT);
    }

    public static final Response getResponse(Map objectModel) {
        return (Response)objectModel.get(RESPONSE_OBJECT);
    }

    public static final Context getContext(Map objectModel) {
        return (Context)objectModel.get(CONTEXT_OBJECT);
    }

    public static final Long getExpires(Map objectModel) {
        return (Long)objectModel.get(EXPIRES_OBJECT);
    }
    
    public static final Throwable getThrowable(Map objectModel) {
        return (Throwable)objectModel.get(THROWABLE_OBJECT);
    }
}