Source code: gnu/javax/swing/text/html/parser/models/transformer.java
1 /* transformer.java -- Content model transforms.
2 Copyright (C) 2005 Free Software Foundation, Inc.
3
4 This file is part of GNU Classpath.
5
6 GNU Classpath is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
9 any later version.
10
11 GNU Classpath is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with GNU Classpath; see the file COPYING. If not, write to the
18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
19 02110-1301 USA.
20
21 Linking this library statically or dynamically with other modules is
22 making a combined work based on this library. Thus, the terms and
23 conditions of the GNU General Public License cover the whole
24 combination.
25
26 As a special exception, the copyright holders of this library give you
27 permission to link this library with independent modules to produce an
28 executable, regardless of the license terms of these independent
29 modules, and to copy and distribute the resulting executable under
30 terms of your choice, provided that you also meet, for each linked
31 independent module, the terms and conditions of the license of that
32 module. An independent module is a module which is not derived from
33 or based on this library. If you modify this library, you may extend
34 this exception to your version of the library, but you are not
35 obligated to do so. If you do not wish to do so, delete this
36 exception statement from your version. */
37
38
39 package gnu.javax.swing.text.html.parser.models;
40
41 import java.io.Serializable;
42
43 import javax.swing.text.html.parser.ContentModel;
44 import javax.swing.text.html.parser.DTD;
45
46 /**
47 * Transforms the standard ContentModel tree into the internal representation,
48 * used in this implementation.
49 * @author Audrius Meskauskas, Lithuania (AudriusA@Bioinformatics.org)
50 */
51 public class transformer
52 implements Serializable
53 {
54 private static final long serialVersionUID = 1;
55
56 /**
57 * All binary operators.
58 */
59 protected static String binary = "&|,";
60
61 /**
62 * All unary operators.
63 */
64 protected static String unary = "+*?";
65
66 /**
67 * Measure length of the linked list of the content models.
68 * @param c The heading element of the linked list.
69 * @return the length of the list (0 for null 1 if c!=null and c.next==null,
70 * etc.
71 */
72 public static int measureChainLength(ContentModel c)
73 {
74 if (c == null)
75 return 0;
76 else
77 return measureChainLength(c.next) + 1;
78 }
79
80 /**
81 * Transform into internal representation without usind dtd.
82 * This should be used only for testing.
83 */
84 public static node transform(ContentModel c)
85 {
86 return transform(c, null);
87 }
88
89 /**
90 * Transform into internal representation.
91 * @param c a model to transform
92 * @return a transformed model
93 * @throws Error if the model structure contains errors.
94 */
95 public static node transform(ContentModel c, DTD dtd)
96 {
97 // Handle the special cases first.
98 if (c.content instanceof node)
99 return (node) c.content;
100
101 // Do the typical transform.
102 node n;
103
104 /* Case with the single token */
105 if (c.next == null)
106 {
107 n = optionalTransform(c, dtd);
108 }
109 else /* Case with the chain of the multiple tokens. */
110 {
111 node[] l = new node[ measureChainLength(c) ];
112 ContentModel m = c;
113 for (int i = 0; i < l.length; i++)
114 {
115 if (m.content instanceof ContentModel)
116 {
117 ContentModel nested = (ContentModel) m.content;
118 if (nested.next == null &&
119 !(nested.content instanceof ContentModel)
120 )
121 {
122 l [ i ] =
123 new node((char) m.type, (char) nested.type, nested.content);
124 }
125 else
126 {
127 l [ i ] = transform(nested, dtd);
128 }
129 }
130 else
131 l [ i ] = new node((char) 0, (char) 0, m.content);
132 addtype(l [ i ], (char) m.type);
133 m = m.next;
134 }
135
136 if (isBinary(c.type))
137 for (int i = 0; i < l.length; i++)
138 {
139 l [ i ].binary = (char) c.type;
140 }
141
142 n = new list(l);
143 }
144
145 addtype(n, (char) c.type);
146
147 return n;
148 }
149
150 /**
151 * True for binary operator
152 * @param c a character to test
153 * @return true for [ ,&| ], false otherwise.
154 */
155 private static boolean isBinary(int c)
156 {
157 return binary.indexOf((char) c) >= 0;
158 }
159
160 /**
161 * True for unary operator.
162 * @param c a character to test
163 * @return true for [ +?* ], false otherwise.
164 */
165 private static boolean isUnary(int c)
166 {
167 return unary.indexOf((char) c) >= 0;
168 }
169
170 /**
171 * Assign an operation type for the given node.
172 * @param n A node to set the operation to.
173 * @param type Either binary or unary operation, is assigned to the
174 * corresponding field of the node.
175 * @throws error if the operation type is not
176 * representing a valid unary or binary operation.
177 */
178 private static void addtype(node n, char type)
179 {
180 if (isBinary(type))
181 n.binary = type;
182
183 else if (isUnary(type))
184 n.unary = type;
185
186 else if (type != 0)
187 throw new Error("Invalid operation '" + (char) type + "'");
188 }
189
190 private static node optionalTransform(ContentModel c, DTD dtd)
191 {
192 node n;
193 if (c.content instanceof ContentModel)
194 n = transform((ContentModel) c.content, dtd);
195 else
196
197 /* A single token with the specified operation */
198 n = new node((char) 0, (char) 0, c.content);
199 return n;
200 }
201 }