001/*
002 * ====================================================================
003 * Licensed to the Apache Software Foundation (ASF) under one
004 * or more contributor license agreements.  See the NOTICE file
005 * distributed with this work for additional information
006 * regarding copyright ownership.  The ASF licenses this file
007 * to you under the Apache License, Version 2.0 (the
008 * "License"); you may not use this file except in compliance
009 * with the License.  You may obtain a copy of the License at
010 *
011 *   http://www.apache.org/licenses/LICENSE-2.0
012 *
013 * Unless required by applicable law or agreed to in writing,
014 * software distributed under the License is distributed on an
015 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
016 * KIND, either express or implied.  See the License for the
017 * specific language governing permissions and limitations
018 * under the License.
019 * ====================================================================
020 *
021 * This software consists of voluntary contributions made by many
022 * individuals on behalf of the Apache Software Foundation.  For more
023 * information on the Apache Software Foundation, please see
024 * <http://www.apache.org/>.
025 *
026 */
027
028package org.apache.http;
029
030/**
031 * One element of an HTTP {@link Header header} value consisting of
032 * a name / value pair and a number of optional name / value parameters.
033 * <p>
034 * Some HTTP headers (such as the set-cookie header) have values that
035 * can be decomposed into multiple elements.  Such headers must be in the
036 * following form:
037 * </p>
038 * <pre>
039 * header  = [ element ] *( "," [ element ] )
040 * element = name [ "=" [ value ] ] *( ";" [ param ] )
041 * param   = name [ "=" [ value ] ]
042 *
043 * name    = token
044 * value   = ( token | quoted-string )
045 *
046 * token         = 1*&lt;any char except "=", ",", ";", &lt;"&gt; and
047 *                       white space&gt;
048 * quoted-string = &lt;"&gt; *( text | quoted-char ) &lt;"&gt;
049 * text          = any char except &lt;"&gt;
050 * quoted-char   = "\" char
051 * </pre>
052 * <p>
053 * Any amount of white space is allowed between any part of the
054 * header, element or param and is ignored. A missing value in any
055 * element or param will be stored as the empty {@link String};
056 * if the "=" is also missing <var>null</var> will be stored instead.
057 *
058 * @since 4.0
059 */
060public interface HeaderElement {
061
062    /**
063     * Returns header element name.
064     *
065     * @return header element name
066     */
067    String getName();
068
069    /**
070     * Returns header element value.
071     *
072     * @return header element value
073     */
074    String getValue();
075
076    /**
077     * Returns an array of name / value pairs.
078     *
079     * @return array of name / value pairs
080     */
081    NameValuePair[] getParameters();
082
083    /**
084     * Returns the first parameter with the given name.
085     *
086     * @param name parameter name
087     *
088     * @return name / value pair
089     */
090    NameValuePair getParameterByName(String name);
091
092    /**
093     * Returns the total count of parameters.
094     *
095     * @return parameter count
096     */
097    int getParameterCount();
098
099    /**
100     * Returns parameter with the given index.
101     *
102     * @param index index
103     * @return name / value pair
104     */
105    NameValuePair getParameter(int index);
106
107}
108