1/*
2 * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/module-main/src/main/java/org/apache/http/message/BasicHeaderElementIterator.java $
3 * $Revision: 592088 $
4 * $Date: 2007-11-05 09:03:39 -0800 (Mon, 05 Nov 2007) $
5 *
6 * ====================================================================
7 * Licensed to the Apache Software Foundation (ASF) under one
8 * or more contributor license agreements.  See the NOTICE file
9 * distributed with this work for additional information
10 * regarding copyright ownership.  The ASF licenses this file
11 * to you under the Apache License, Version 2.0 (the
12 * "License"); you may not use this file except in compliance
13 * with the License.  You may obtain a copy of the License at
14 *
15 *   http://www.apache.org/licenses/LICENSE-2.0
16 *
17 * Unless required by applicable law or agreed to in writing,
18 * software distributed under the License is distributed on an
19 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
20 * KIND, either express or implied.  See the License for the
21 * specific language governing permissions and limitations
22 * under the License.
23 * ====================================================================
24 *
25 * This software consists of voluntary contributions made by many
26 * individuals on behalf of the Apache Software Foundation.  For more
27 * information on the Apache Software Foundation, please see
28 * <http://www.apache.org/>.
29 *
30 */
31
32package org.apache.http.message;
33
34import java.util.NoSuchElementException;
35
36import org.apache.http.FormattedHeader;
37import org.apache.http.Header;
38import org.apache.http.HeaderElement;
39import org.apache.http.HeaderElementIterator;
40import org.apache.http.HeaderIterator;
41import org.apache.http.util.CharArrayBuffer;
42
43/**
44 * Basic implementation of a {@link HeaderElementIterator}.
45 *
46 * @version $Revision: 592088 $
47 *
48 * @author Andrea Selva <selva.andre at gmail.com>
49 * @author Oleg Kalnichevski <oleg at ural.ru>
50 */
51public class BasicHeaderElementIterator implements HeaderElementIterator {
52
53    private final HeaderIterator headerIt;
54    private final HeaderValueParser parser;
55
56    private HeaderElement currentElement = null;
57    private CharArrayBuffer buffer = null;
58    private ParserCursor cursor = null;
59
60    /**
61     * Creates a new instance of BasicHeaderElementIterator
62     */
63    public BasicHeaderElementIterator(
64            final HeaderIterator headerIterator,
65            final HeaderValueParser parser) {
66        if (headerIterator == null) {
67            throw new IllegalArgumentException("Header iterator may not be null");
68        }
69        if (parser == null) {
70            throw new IllegalArgumentException("Parser may not be null");
71        }
72        this.headerIt = headerIterator;
73        this.parser = parser;
74    }
75
76
77    public BasicHeaderElementIterator(final HeaderIterator headerIterator) {
78        this(headerIterator, BasicHeaderValueParser.DEFAULT);
79    }
80
81
82    private void bufferHeaderValue() {
83        this.cursor = null;
84        this.buffer = null;
85        while (this.headerIt.hasNext()) {
86            Header h = this.headerIt.nextHeader();
87            if (h instanceof FormattedHeader) {
88                this.buffer = ((FormattedHeader) h).getBuffer();
89                this.cursor = new ParserCursor(0, this.buffer.length());
90                this.cursor.updatePos(((FormattedHeader) h).getValuePos());
91                break;
92            } else {
93                String value = h.getValue();
94                if (value != null) {
95                    this.buffer = new CharArrayBuffer(value.length());
96                    this.buffer.append(value);
97                    this.cursor = new ParserCursor(0, this.buffer.length());
98                    break;
99                }
100            }
101        }
102    }
103
104    private void parseNextElement() {
105        // loop while there are headers left to parse
106        while (this.headerIt.hasNext() || this.cursor != null) {
107            if (this.cursor == null || this.cursor.atEnd()) {
108                // get next header value
109                bufferHeaderValue();
110            }
111            // Anything buffered?
112            if (this.cursor != null) {
113                // loop while there is data in the buffer
114                while (!this.cursor.atEnd()) {
115                    HeaderElement e = this.parser.parseHeaderElement(this.buffer, this.cursor);
116                    if (!(e.getName().length() == 0 && e.getValue() == null)) {
117                        // Found something
118                        this.currentElement = e;
119                        return;
120                    }
121                }
122                // if at the end of the buffer
123                if (this.cursor.atEnd()) {
124                    // discard it
125                    this.cursor = null;
126                    this.buffer = null;
127                }
128            }
129        }
130    }
131
132    public boolean hasNext() {
133        if (this.currentElement == null) {
134            parseNextElement();
135        }
136        return this.currentElement != null;
137    }
138
139    public HeaderElement nextElement() throws NoSuchElementException {
140        if (this.currentElement == null) {
141            parseNextElement();
142        }
143
144        if (this.currentElement == null) {
145            throw new NoSuchElementException("No more header elements available");
146        }
147
148        HeaderElement element = this.currentElement;
149        this.currentElement = null;
150        return element;
151    }
152
153    public final Object next() throws NoSuchElementException {
154        return nextElement();
155    }
156
157    public void remove() throws UnsupportedOperationException {
158        throw new UnsupportedOperationException("Remove not supported");
159    }
160
161}