Source for gnu.javax.swing.text.html.parser.models.list

   1: /* list.java --
   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: /**
  44:  * Part of the internal representation of the content model.
  45:  * @author Audrius Meskauskas, Lithuania (AudriusA@Bioinformatics.org)
  46:  */
  47: public class list
  48:   extends node
  49:   implements Serializable
  50: {
  51:   private static final long serialVersionUID = 1;
  52: 
  53:   /**
  54:    * Setting to true means that the list nodes must always be connected
  55:    * by the same operation. This is far safer and clearer, but not
  56:    * required by default standard.
  57:    */
  58:   public static boolean CLEAR;
  59: 
  60:   /**
  61:    * A list of nodes.
  62:    */
  63:   public final node[] nodes;
  64: 
  65:   /**
  66:    * Creates a new model list that is a member of some enclosing list.
  67:    * @param binary_operator An operator with that this list is connected
  68:    * with other members of the enclosing list.
  69:    * @param unary_operator The unary operator for this list.
  70:    * @param a_nodes The nodes inside this list.
  71:    */
  72:   public list(char binary_operator, char unary_operator, node[] a_nodes)
  73:   {
  74:     super(binary_operator, unary_operator, a_nodes);
  75:     nodes = a_nodes;
  76:   }
  77: 
  78:   /**
  79:    * Creates a new model list. Assigns the previous field.
  80:    * @param a_nodes The nodes for this list.
  81:    * @throws an error if the node elements are connected by the
  82:    * different operations. This is not supported, use grouping.
  83:    */
  84:   public list(node[] a_nodes)
  85:        throws Error
  86:   {
  87:     this(',', (char) 0, a_nodes);
  88: 
  89:     int operation = nodes [ 0 ].binary;
  90: 
  91:     for (int i = 0; i < nodes.length; i++)
  92:       {
  93:         if (CLEAR && nodes [ i ].binary != operation)
  94:           throw new Error("List members can only be connected by " +
  95:                           "the same operation, use grouping"
  96:                          );
  97: 
  98:         if (i > 0)
  99:           nodes [ i ].previous = nodes [ i - 1 ];
 100:       }
 101:   }
 102: 
 103:   /**
 104:    * Returns true if all members in the list are closed.
 105:    */
 106:   public boolean isClosed()
 107:   {
 108:     if (super.isClosed())
 109:       return true;
 110:     for (int i = 0; i < nodes.length; i++)
 111:       {
 112:         if (!nodes [ i ].isClosed())
 113:           return false;
 114:       }
 115:     return true;
 116:   }
 117: 
 118:   /**
 119:    * Find the token that could match as the next token in
 120:    * the token list.
 121:    *
 122:    * @return Such token object or null if none is found.
 123:    */
 124:   public Object findFreeNode()
 125:   {
 126:     Object fn;
 127:     for (int j = 0; j < nodes.length; j++)
 128:       {
 129:         if (!nodes [ j ].isClosed())
 130:           {
 131:             fn = nodes [ j ].findFreeNode();
 132:             if (fn != null)
 133:               return fn;
 134:           }
 135:       }
 136:     return null;
 137:   }
 138: 
 139:   /**
 140:    * Tries to match this list agains the given token sequence.
 141:    * @param tokens the sequence of the tokens to match.
 142:    * @return true if the valid match is found.
 143:    */
 144:   public boolean matches(Object[] tokens)
 145:   {
 146:     reset();
 147: 
 148:     Object x;
 149:     boolean m;
 150:     boolean matched = false;
 151: 
 152:     for (int i = 0; i < tokens.length; i++)
 153:       {
 154:         matched = false;
 155:         x = tokens [ i ];
 156: 
 157:         nodescan: 
 158:         for (int j = 0; j < nodes.length; j++)
 159:           {
 160:             if (!nodes [ j ].isClosed())
 161:               {
 162:                 m = nodes [ j ].performMatch(x);
 163: 
 164:                 if (m)
 165:                   {
 166:                     matched = true;
 167:                     break nodescan;
 168:                   }
 169:               }
 170:           }
 171:         if (!matched)
 172:           return false;
 173:       }
 174: 
 175:     boolean valid = true;
 176: 
 177:     for (int i = 0; i < nodes.length; i++)
 178:       {
 179:         if (!nodes [ i ].valid())
 180:           valid = false;
 181:       }
 182: 
 183:     return valid;
 184:   }
 185: 
 186:   /**
 187:    * The list never closes, despite it is trated as closed
 188:    * if all members in the list are closed.
 189:    * @return false.
 190:    */
 191:   public boolean mustClose()
 192:   {
 193:     return false;
 194:   }
 195: 
 196:   /**
 197:    * Perform a match operation for the single token
 198:    * against this list.
 199:    * @param token a token to match.
 200:    * @return true if the match is found.
 201:    */
 202:   public boolean performMatch(Object token)
 203:   {
 204:     boolean ok = false;
 205:     Matching: 
 206:     for (int i = 0; i < nodes.length; i++)
 207:       {
 208:         ok = nodes [ i ].performMatch(token);
 209: 
 210:         if (ok)
 211:           break Matching;
 212:       }
 213: 
 214:     if (ok)
 215:       matches();
 216: 
 217:     return ok;
 218:   }
 219: 
 220:   /**
 221:    * Prepeares the list for the next matching operation.
 222:    */
 223:   public void reset()
 224:   {
 225:     super.reset();
 226:     for (int i = 0; i < nodes.length; i++)
 227:       nodes [ i ].reset();
 228:   }
 229: 
 230:   /**
 231:    * Check if the provided token can match as a next token in the
 232:    * list. In the case of match, the list state changes, moving
 233:    * current position after the matched token. However if this method
 234:    * returns a suggested new token to insert before the provided one,
 235:    * the state of the list does not change.
 236:    * @return Boolean.TRUE if the match is found,
 237:    * Boolean.FALSE if the match is not possible and no token can be
 238:    * inserted to make the match valid. Otherwise, returns the
 239:    * token object that can be inserted before the last token in the
 240:    * list, probably (not for sure) making the match valid.
 241:    * If the object is an instance of Element or TagElement,
 242:    * it is first ensured that the object flag "omit start" is set.
 243:    */
 244:   public Object show(Object x)
 245:   {
 246:     boolean m;
 247:     boolean matched = false;
 248: 
 249:     nodescan: 
 250:     for (int j = 0; j < nodes.length; j++)
 251:       {
 252:         if (!nodes [ j ].isClosed())
 253:           {
 254:             m = nodes [ j ].performMatch(x);
 255: 
 256:             if (m)
 257:               {
 258:                 matched = true;
 259:                 break nodescan;
 260:               }
 261:             else
 262:               {
 263:                 // For comma operation, only first not closed
 264:                 // node must be tested for a match.
 265:                 // unless it allows matching zero times.
 266:                 if (binary == ',' &&
 267:                     !(nodes [ j ].unary == '?' || nodes [ j ].unary == '*')
 268:                    )
 269:                   break nodescan;
 270:               }
 271:           }
 272:       }
 273: 
 274:     if (!matched)
 275:       {
 276:         // Find and return that would be matched.
 277:         Object freeNode = findFreeNode();
 278:         if (freeNode == null)
 279:           return Boolean.FALSE;
 280:         else
 281:           return freeNode;
 282:       }
 283: 
 284:     for (int i = 0; i < nodes.length; i++)
 285:       if (!nodes [ i ].validPreliminary())
 286:         {
 287:           return Boolean.FALSE;
 288:         }
 289: 
 290:     return Boolean.TRUE;
 291:   }
 292: 
 293:   /**
 294:    * Returns a string representation of the list.
 295:    * @return String representation, similar to BNF expression.
 296:    */
 297:   public String toString()
 298:   {
 299:     StringBuffer b = new StringBuffer();
 300:     b.append(" ( ");
 301:     for (int i = 0; i < nodes.length; i++)
 302:       {
 303:         if (i > 0)
 304:           b.append(" " + (char) nodes [ i ].binary + " ");
 305:         b.append(nodes [ i ]);
 306:       }
 307: 
 308:     b.append(" )");
 309:     if (unary != 0)
 310:       b.append((char) unary);
 311:     else
 312:       b.append(' ');
 313:     return b.toString();
 314:   }
 315: 
 316:   /**
 317:    * Returns true if all memebers in the list are valid.
 318:    */
 319:   public boolean valid()
 320:   {
 321:     for (int i = 0; i < nodes.length; i++)
 322:       {
 323:         if (!nodes [ i ].valid())
 324:           return false;
 325:       }
 326:     return true;
 327:   }
 328: 
 329:   /**
 330:    * Returns true if all memebers in the list are either valid
 331:    * or unvisited. The unvisited members can become valid after
 332:    * more tokens will be shown.
 333:    */
 334:   public boolean validPreliminary()
 335:   {
 336:     if (silenceAllowed())
 337:       {
 338:         boolean everVisited = false;
 339:         for (int i = 0; i < nodes.length; i++)
 340:           {
 341:             if (nodes [ i ].visits > 0)
 342:               {
 343:                 everVisited = true;
 344:                 break;
 345:               }
 346:           }
 347:         if (!everVisited)
 348:           return true;
 349:       }
 350: 
 351:     for (int i = 0; i < nodes.length; i++)
 352:       {
 353:         if (!nodes [ i ].validPreliminary())
 354:           return false;
 355:       }
 356:     return true;
 357:   }
 358: 
 359:   /**
 360:    * Closes all members in the list.
 361:    */
 362:   protected void close()
 363:   {
 364:     super.close();
 365:     for (int i = 0; i < nodes.length; i++)
 366:       {
 367:         nodes [ i ].close();
 368:       }
 369:   }
 370: 
 371:   /**
 372:    * Compare given token with the token of this node.
 373:    * If the token represents a <code>list</code>, the call may be
 374:    * delegeted to the child subnodes.
 375:    * @param a_token A token to compare.
 376:    * @return True if the token matches the token of this node.
 377:    */
 378:   protected boolean compare(Object a_token)
 379:   {
 380:     return performMatch(a_token);
 381:   }
 382: }