J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1998-2000 Sun Microsystems, Inc. All Rights Reserved. |
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 | * |
| 5 | * This code is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License version 2 only, as |
| 7 | * published by the Free Software Foundation. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun in the LICENSE file that accompanied this code. |
| 10 | * |
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 14 | * version 2 for more details (a copy is included in the LICENSE file that |
| 15 | * accompanied this code). |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License version |
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | * |
| 21 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package javax.swing.text.html.parser; |
| 27 | |
| 28 | /** |
| 29 | * A content model state. This is basically a list of pointers to |
| 30 | * the BNF expression representing the model (the ContentModel). |
| 31 | * Each element in a DTD has a content model which describes the |
| 32 | * elements that may occur inside, and the order in which they can |
| 33 | * occur. |
| 34 | * <p> |
| 35 | * Each time a token is reduced a new state is created. |
| 36 | * <p> |
| 37 | * See Annex H on page 556 of the SGML handbook for more information. |
| 38 | * |
| 39 | * @see Parser |
| 40 | * @see DTD |
| 41 | * @see Element |
| 42 | * @see ContentModel |
| 43 | * @author Arthur van Hoff |
| 44 | */ |
| 45 | class ContentModelState { |
| 46 | ContentModel model; |
| 47 | long value; |
| 48 | ContentModelState next; |
| 49 | |
| 50 | /** |
| 51 | * Create a content model state for a content model. |
| 52 | */ |
| 53 | public ContentModelState(ContentModel model) { |
| 54 | this(model, null, 0); |
| 55 | } |
| 56 | |
| 57 | /** |
| 58 | * Create a content model state for a content model given the |
| 59 | * remaining state that needs to be reduce. |
| 60 | */ |
| 61 | ContentModelState(Object content, ContentModelState next) { |
| 62 | this(content, next, 0); |
| 63 | } |
| 64 | |
| 65 | /** |
| 66 | * Create a content model state for a content model given the |
| 67 | * remaining state that needs to be reduce. |
| 68 | */ |
| 69 | ContentModelState(Object content, ContentModelState next, long value) { |
| 70 | this.model = (ContentModel)content; |
| 71 | this.next = next; |
| 72 | this.value = value; |
| 73 | } |
| 74 | |
| 75 | /** |
| 76 | * Return the content model that is relevant to the current state. |
| 77 | */ |
| 78 | public ContentModel getModel() { |
| 79 | ContentModel m = model; |
| 80 | for (int i = 0; i < value; i++) { |
| 81 | if (m.next != null) { |
| 82 | m = m.next; |
| 83 | } else { |
| 84 | return null; |
| 85 | } |
| 86 | } |
| 87 | return m; |
| 88 | } |
| 89 | |
| 90 | /** |
| 91 | * Check if the state can be terminated. That is there are no more |
| 92 | * tokens required in the input stream. |
| 93 | * @return true if the model can terminate without further input |
| 94 | */ |
| 95 | public boolean terminate() { |
| 96 | switch (model.type) { |
| 97 | case '+': |
| 98 | if ((value == 0) && !(model).empty()) { |
| 99 | return false; |
| 100 | } |
| 101 | case '*': |
| 102 | case '?': |
| 103 | return (next == null) || next.terminate(); |
| 104 | |
| 105 | case '|': |
| 106 | for (ContentModel m = (ContentModel)model.content ; m != null ; m = m.next) { |
| 107 | if (m.empty()) { |
| 108 | return (next == null) || next.terminate(); |
| 109 | } |
| 110 | } |
| 111 | return false; |
| 112 | |
| 113 | case '&': { |
| 114 | ContentModel m = (ContentModel)model.content; |
| 115 | |
| 116 | for (int i = 0 ; m != null ; i++, m = m.next) { |
| 117 | if ((value & (1L << i)) == 0) { |
| 118 | if (!m.empty()) { |
| 119 | return false; |
| 120 | } |
| 121 | } |
| 122 | } |
| 123 | return (next == null) || next.terminate(); |
| 124 | } |
| 125 | |
| 126 | case ',': { |
| 127 | ContentModel m = (ContentModel)model.content; |
| 128 | for (int i = 0 ; i < value ; i++, m = m.next); |
| 129 | |
| 130 | for (; (m != null) && m.empty() ; m = m.next); |
| 131 | if (m != null) { |
| 132 | return false; |
| 133 | } |
| 134 | return (next == null) || next.terminate(); |
| 135 | } |
| 136 | |
| 137 | default: |
| 138 | return false; |
| 139 | } |
| 140 | } |
| 141 | |
| 142 | /** |
| 143 | * Check if the state can be terminated. That is there are no more |
| 144 | * tokens required in the input stream. |
| 145 | * @return the only possible element that can occur next |
| 146 | */ |
| 147 | public Element first() { |
| 148 | switch (model.type) { |
| 149 | case '*': |
| 150 | case '?': |
| 151 | case '|': |
| 152 | case '&': |
| 153 | return null; |
| 154 | |
| 155 | case '+': |
| 156 | return model.first(); |
| 157 | |
| 158 | case ',': { |
| 159 | ContentModel m = (ContentModel)model.content; |
| 160 | for (int i = 0 ; i < value ; i++, m = m.next); |
| 161 | return m.first(); |
| 162 | } |
| 163 | |
| 164 | default: |
| 165 | return model.first(); |
| 166 | } |
| 167 | } |
| 168 | |
| 169 | /** |
| 170 | * Advance this state to a new state. An exception is thrown if the |
| 171 | * token is illegal at this point in the content model. |
| 172 | * @return next state after reducing a token |
| 173 | */ |
| 174 | public ContentModelState advance(Object token) { |
| 175 | switch (model.type) { |
| 176 | case '+': |
| 177 | if (model.first(token)) { |
| 178 | return new ContentModelState(model.content, |
| 179 | new ContentModelState(model, next, value + 1)).advance(token); |
| 180 | } |
| 181 | if (value != 0) { |
| 182 | if (next != null) { |
| 183 | return next.advance(token); |
| 184 | } else { |
| 185 | return null; |
| 186 | } |
| 187 | } |
| 188 | break; |
| 189 | |
| 190 | case '*': |
| 191 | if (model.first(token)) { |
| 192 | return new ContentModelState(model.content, this).advance(token); |
| 193 | } |
| 194 | if (next != null) { |
| 195 | return next.advance(token); |
| 196 | } else { |
| 197 | return null; |
| 198 | } |
| 199 | |
| 200 | case '?': |
| 201 | if (model.first(token)) { |
| 202 | return new ContentModelState(model.content, next).advance(token); |
| 203 | } |
| 204 | if (next != null) { |
| 205 | return next.advance(token); |
| 206 | } else { |
| 207 | return null; |
| 208 | } |
| 209 | |
| 210 | case '|': |
| 211 | for (ContentModel m = (ContentModel)model.content ; m != null ; m = m.next) { |
| 212 | if (m.first(token)) { |
| 213 | return new ContentModelState(m, next).advance(token); |
| 214 | } |
| 215 | } |
| 216 | break; |
| 217 | |
| 218 | case ',': { |
| 219 | ContentModel m = (ContentModel)model.content; |
| 220 | for (int i = 0 ; i < value ; i++, m = m.next); |
| 221 | |
| 222 | if (m.first(token) || m.empty()) { |
| 223 | if (m.next == null) { |
| 224 | return new ContentModelState(m, next).advance(token); |
| 225 | } else { |
| 226 | return new ContentModelState(m, |
| 227 | new ContentModelState(model, next, value + 1)).advance(token); |
| 228 | } |
| 229 | } |
| 230 | break; |
| 231 | } |
| 232 | |
| 233 | case '&': { |
| 234 | ContentModel m = (ContentModel)model.content; |
| 235 | boolean complete = true; |
| 236 | |
| 237 | for (int i = 0 ; m != null ; i++, m = m.next) { |
| 238 | if ((value & (1L << i)) == 0) { |
| 239 | if (m.first(token)) { |
| 240 | return new ContentModelState(m, |
| 241 | new ContentModelState(model, next, value | (1L << i))).advance(token); |
| 242 | } |
| 243 | if (!m.empty()) { |
| 244 | complete = false; |
| 245 | } |
| 246 | } |
| 247 | } |
| 248 | if (complete) { |
| 249 | if (next != null) { |
| 250 | return next.advance(token); |
| 251 | } else { |
| 252 | return null; |
| 253 | } |
| 254 | } |
| 255 | break; |
| 256 | } |
| 257 | |
| 258 | default: |
| 259 | if (model.content == token) { |
| 260 | if (next == null && (token instanceof Element) && |
| 261 | ((Element)token).content != null) { |
| 262 | return new ContentModelState(((Element)token).content); |
| 263 | } |
| 264 | return next; |
| 265 | } |
| 266 | // PENDING: Currently we don't correctly deal with optional start |
| 267 | // tags. This can most notably be seen with the 4.01 spec where |
| 268 | // TBODY's start and end tags are optional. |
| 269 | // Uncommenting this and the PENDING in ContentModel will |
| 270 | // correctly skip the omit tags, but the delegate is not notified. |
| 271 | // Some additional API needs to be added to track skipped tags, |
| 272 | // and this can then be added back. |
| 273 | /* |
| 274 | if ((model.content instanceof Element)) { |
| 275 | Element e = (Element)model.content; |
| 276 | |
| 277 | if (e.omitStart() && e.content != null) { |
| 278 | return new ContentModelState(e.content, next).advance( |
| 279 | token); |
| 280 | } |
| 281 | } |
| 282 | */ |
| 283 | } |
| 284 | |
| 285 | // We used to throw this exception at this point. However, it |
| 286 | // was determined that throwing this exception was more expensive |
| 287 | // than returning null, and we could not justify to ourselves why |
| 288 | // it was necessary to throw an exception, rather than simply |
| 289 | // returning null. I'm leaving it in a commented out state so |
| 290 | // that it can be easily restored if the situation ever arises. |
| 291 | // |
| 292 | // throw new IllegalArgumentException("invalid token: " + token); |
| 293 | return null; |
| 294 | } |
| 295 | } |