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.message;
michael@0: 
michael@0: import java.util.NoSuchElementException;
michael@0: 
michael@0: import ch.boye.httpclientandroidlib.Header;
michael@0: import ch.boye.httpclientandroidlib.HeaderIterator;
michael@0: 
michael@0: /**
michael@0:  * Basic implementation of a {@link HeaderIterator}.
michael@0:  *
michael@0:  * @since 4.0
michael@0:  */
michael@0: public class BasicHeaderIterator implements HeaderIterator {
michael@0: 
michael@0:     /**
michael@0:      * An array of headers to iterate over.
michael@0:      * Not all elements of this array are necessarily part of the iteration.
michael@0:      * This array will never be modified by the iterator.
michael@0:      * Derived implementations are expected to adhere to this restriction.
michael@0:      */
michael@0:     protected final Header[] allHeaders;
michael@0: 
michael@0: 
michael@0:     /**
michael@0:      * The position of the next header in {@link #allHeaders allHeaders}.
michael@0:      * Negative if the iteration is over.
michael@0:      */
michael@0:     protected int currentIndex;
michael@0: 
michael@0: 
michael@0:     /**
michael@0:      * The header name to filter by.
michael@0:      * <code>null</code> to iterate over all headers in the array.
michael@0:      */
michael@0:     protected String headerName;
michael@0: 
michael@0: 
michael@0: 
michael@0:     /**
michael@0:      * Creates a new header iterator.
michael@0:      *
michael@0:      * @param headers   an array of headers over which to iterate
michael@0:      * @param name      the name of the headers over which to iterate, or
michael@0:      *                  <code>null</code> for any
michael@0:      */
michael@0:     public BasicHeaderIterator(Header[] headers, String name) {
michael@0:         if (headers == null) {
michael@0:             throw new IllegalArgumentException
michael@0:                 ("Header array must not be null.");
michael@0:         }
michael@0: 
michael@0:         this.allHeaders = headers;
michael@0:         this.headerName = name;
michael@0:         this.currentIndex = findNext(-1);
michael@0:     }
michael@0: 
michael@0: 
michael@0:     /**
michael@0:      * Determines the index of the next header.
michael@0:      *
michael@0:      * @param from      one less than the index to consider first,
michael@0:      *                  -1 to search for the first header
michael@0:      *
michael@0:      * @return  the index of the next header that matches the filter name,
michael@0:      *          or negative if there are no more headers
michael@0:      */
michael@0:     protected int findNext(int from) {
michael@0:         if (from < -1)
michael@0:             return -1;
michael@0: 
michael@0:         final int to = this.allHeaders.length-1;
michael@0:         boolean found = false;
michael@0:         while (!found && (from < to)) {
michael@0:             from++;
michael@0:             found = filterHeader(from);
michael@0:         }
michael@0:         return found ? from : -1;
michael@0:     }
michael@0: 
michael@0: 
michael@0:     /**
michael@0:      * Checks whether a header is part of the iteration.
michael@0:      *
michael@0:      * @param index     the index of the header to check
michael@0:      *
michael@0:      * @return  <code>true</code> if the header should be part of the
michael@0:      *          iteration, <code>false</code> to skip
michael@0:      */
michael@0:     protected boolean filterHeader(int index) {
michael@0:         return (this.headerName == null) ||
michael@0:             this.headerName.equalsIgnoreCase(this.allHeaders[index].getName());
michael@0:     }
michael@0: 
michael@0: 
michael@0:     // non-javadoc, see interface HeaderIterator
michael@0:     public boolean hasNext() {
michael@0:         return (this.currentIndex >= 0);
michael@0:     }
michael@0: 
michael@0: 
michael@0:     /**
michael@0:      * Obtains the next header from this iteration.
michael@0:      *
michael@0:      * @return  the next header in this iteration
michael@0:      *
michael@0:      * @throws NoSuchElementException   if there are no more headers
michael@0:      */
michael@0:     public Header nextHeader()
michael@0:         throws NoSuchElementException {
michael@0: 
michael@0:         final int current = this.currentIndex;
michael@0:         if (current < 0) {
michael@0:             throw new NoSuchElementException("Iteration already finished.");
michael@0:         }
michael@0: 
michael@0:         this.currentIndex = findNext(current);
michael@0: 
michael@0:         return this.allHeaders[current];
michael@0:     }
michael@0: 
michael@0: 
michael@0:     /**
michael@0:      * Returns the next header.
michael@0:      * Same as {@link #nextHeader nextHeader}, but not type-safe.
michael@0:      *
michael@0:      * @return  the next header in this iteration
michael@0:      *
michael@0:      * @throws NoSuchElementException   if there are no more headers
michael@0:      */
michael@0:     public final Object next()
michael@0:         throws NoSuchElementException {
michael@0:         return nextHeader();
michael@0:     }
michael@0: 
michael@0: 
michael@0:     /**
michael@0:      * Removing headers is not supported.
michael@0:      *
michael@0:      * @throws UnsupportedOperationException    always
michael@0:      */
michael@0:     public void remove()
michael@0:         throws UnsupportedOperationException {
michael@0: 
michael@0:         throw new UnsupportedOperationException
michael@0:             ("Removing headers is not supported.");
michael@0:     }
michael@0: }