michael@0: /*
michael@0:  * ====================================================================
michael@0:  * Licensed to the Apache Software Foundation (ASF) under one
michael@0:  * or more contributor license agreements.  See the NOTICE file
michael@0:  * distributed with this work for additional information
michael@0:  * regarding copyright ownership.  The ASF licenses this file
michael@0:  * to you under the Apache License, Version 2.0 (the
michael@0:  * "License"); you may not use this file except in compliance
michael@0:  * with the License.  You may obtain a copy of the License at
michael@0:  *
michael@0:  *   http://www.apache.org/licenses/LICENSE-2.0
michael@0:  *
michael@0:  * Unless required by applicable law or agreed to in writing,
michael@0:  * software distributed under the License is distributed on an
michael@0:  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
michael@0:  * KIND, either express or implied.  See the License for the
michael@0:  * specific language governing permissions and limitations
michael@0:  * under the License.
michael@0:  * ====================================================================
michael@0:  *
michael@0:  * This software consists of voluntary contributions made by many
michael@0:  * individuals on behalf of the Apache Software Foundation.  For more
michael@0:  * information on the Apache Software Foundation, please see
michael@0:  * <http://www.apache.org/>.
michael@0:  *
michael@0:  */
michael@0: 
michael@0: package ch.boye.httpclientandroidlib.protocol;
michael@0: 
michael@0: /**
michael@0:  * {@link HttpContext} implementation that delegates resolution of an attribute
michael@0:  * to the given default {@link HttpContext} instance if the attribute is not
michael@0:  * present in the local one. The state of the local context can be mutated,
michael@0:  * whereas the default context is treated as read-only.
michael@0:  *
michael@0:  * @since 4.0
michael@0:  */
michael@0: public final class DefaultedHttpContext implements HttpContext {
michael@0: 
michael@0:     private final HttpContext local;
michael@0:     private final HttpContext defaults;
michael@0: 
michael@0:     public DefaultedHttpContext(final HttpContext local, final HttpContext defaults) {
michael@0:         super();
michael@0:         if (local == null) {
michael@0:             throw new IllegalArgumentException("HTTP context may not be null");
michael@0:         }
michael@0:         this.local = local;
michael@0:         this.defaults = defaults;
michael@0:     }
michael@0: 
michael@0:     public Object getAttribute(final String id) {
michael@0:         Object obj = this.local.getAttribute(id);
michael@0:         if (obj == null) {
michael@0:             return this.defaults.getAttribute(id);
michael@0:         } else {
michael@0:             return obj;
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     public Object removeAttribute(final String id) {
michael@0:         return this.local.removeAttribute(id);
michael@0:     }
michael@0: 
michael@0:     public void setAttribute(final String id, final Object obj) {
michael@0:         this.local.setAttribute(id, obj);
michael@0:     }
michael@0: 
michael@0:     public HttpContext getDefaults() {
michael@0:         return this.defaults;
michael@0:     }
michael@0: 
michael@0: }