Source for gnu.xml.aelfred2.XmlReader

   1: /* XmlReader.java --
   2:    Copyright (C) 1999,2000,2001 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: package gnu.xml.aelfred2;
  39: 
  40: import java.io.IOException;
  41: import java.util.Locale;
  42: 
  43: import org.xml.sax.*;
  44: import org.xml.sax.ext.*;
  45: 
  46: import gnu.xml.pipeline.EventFilter;
  47: import gnu.xml.pipeline.ValidationConsumer;
  48: 
  49: 
  50: /**
  51:  * This SAX2 parser optionally layers a validator over the Ælfred2
  52:  * SAX2 parser.  While this will not evaluate every XML validity constraint,
  53:  * it does support all the validity constraints that are of any real utility
  54:  * outside the strict SGML-compatible world.  See the documentation for the
  55:  * SAXDriver class for information about the SAX2 features and properties
  56:  * that are supported, and documentation for the ValidationConsumer for
  57:  * information about what validity constraints may not be supported.
  58:  * (Ælfred2 tests some of those, even in non-validating mode, to
  59:  * achieve better conformance.)
  60:  *
  61:  * <p> Note that due to its internal construction, you can't change most
  62:  * handlers until parse() returns.  This diverges slightly from SAX, which
  63:  * expects later binding to be supported.  Early binding involves less
  64:  * runtime overhead, which is an issue for event pipelines as used inside
  65:  * this parser.  Rather than relying on the parser to handle late binding
  66:  * to your own handlers, do it yourself.
  67:  *
  68:  * @see SAXDriver
  69:  * @see gnu.xml.pipeline.ValidationConsumer
  70:  *
  71:  * @author David Brownell
  72:  */
  73: public final class XmlReader
  74:   implements XMLReader
  75: {
  76: 
  77:   static class FatalErrorHandler
  78:     extends DefaultHandler2
  79:   {
  80: 
  81:     public void error(SAXParseException e)
  82:       throws SAXException
  83:     {
  84:       throw e;
  85:     }
  86: 
  87:   }
  88: 
  89:   private SAXDriver aelfred2 = new SAXDriver();
  90:   private EventFilter filter = new EventFilter();
  91:   private boolean isValidating;
  92:   private boolean active;
  93: 
  94:   /**
  95:    * Constructs a SAX Parser.
  96:    */
  97:   public XmlReader()
  98:   {
  99:   }
 100: 
 101:   /**
 102:    * Constructs a SAX Parser, optionally treating validity errors
 103:    * as if they were fatal errors.
 104:    */
 105:   public XmlReader(boolean invalidIsFatal)
 106:   {
 107:     if (invalidIsFatal)
 108:       {
 109:         setErrorHandler(new FatalErrorHandler());
 110:       }
 111:   }
 112: 
 113:   /**
 114:    * <b>SAX2</b>: Returns the object used to report the logical
 115:    * content of an XML document.
 116:    */
 117:   public ContentHandler getContentHandler()
 118:   {
 119:     return filter.getContentHandler();
 120:   }
 121: 
 122:   /**
 123:    * <b>SAX2</b>: Assigns the object used to report the logical
 124:    * content of an XML document.
 125:    * @exception IllegalStateException if called mid-parse
 126:    */
 127:   public void setContentHandler(ContentHandler handler)
 128:   {
 129:     if (active)
 130:       {
 131:         throw new IllegalStateException("already parsing");
 132:       }
 133:     filter.setContentHandler(handler);
 134:   }
 135: 
 136:   /**
 137:    * <b>SAX2</b>: Returns the object used to process declarations related
 138:    * to notations and unparsed entities.
 139:    */
 140:   public DTDHandler getDTDHandler()
 141:   {
 142:     return filter.getDTDHandler();
 143:   }
 144: 
 145:   /**
 146:    * <b>SAX1</b> Assigns DTD handler
 147:    * @exception IllegalStateException if called mid-parse
 148:    */
 149:   public void setDTDHandler(DTDHandler handler)
 150:   {
 151:     if (active)
 152:       {
 153:         throw new IllegalStateException("already parsing");
 154:       }
 155:     filter.setDTDHandler(handler);
 156:   }
 157: 
 158:   /**
 159:    * <b>SAX2</b>: Returns the object used when resolving external
 160:    * entities during parsing (both general and parameter entities).
 161:    */
 162:   public EntityResolver getEntityResolver()
 163:   {
 164:     return aelfred2.getEntityResolver();
 165:   }
 166: 
 167:   /**
 168:    * <b>SAX1</b> Assigns parser's entity resolver
 169:    */
 170:   public void setEntityResolver(EntityResolver handler)
 171:   {
 172:     aelfred2.setEntityResolver(handler);
 173:   }
 174: 
 175:   /**
 176:    * <b>SAX2</b>: Returns the object used to receive callbacks for XML
 177:    * errors of all levels (fatal, nonfatal, warning); this is never null;
 178:    */
 179:   public ErrorHandler getErrorHandler()
 180:   {
 181:     return aelfred2.getErrorHandler();
 182:   }
 183: 
 184:   /**
 185:    * <b>SAX1</b> Assigns error handler
 186:    * @exception IllegalStateException if called mid-parse
 187:    */
 188:   public void setErrorHandler(ErrorHandler handler)
 189:   {
 190:     if (active)
 191:       {
 192:         throw new IllegalStateException("already parsing");
 193:       }
 194:     aelfred2.setErrorHandler(handler);
 195:   }
 196: 
 197:   /**
 198:    * <b>SAX2</b>:  Assigns the specified property.
 199:    * @exception IllegalStateException if called mid-parse
 200:    */
 201:   public void setProperty(String propertyId, Object value)
 202:     throws SAXNotRecognizedException, SAXNotSupportedException
 203:   {
 204:     if (active)
 205:       {
 206:         throw new IllegalStateException("already parsing");
 207:       }
 208:     if (getProperty(propertyId) != value)
 209:       {
 210:         filter.setProperty(propertyId, value);
 211:       }
 212:   }
 213: 
 214:   /**
 215:    * <b>SAX2</b>:  Returns the specified property.
 216:    */
 217:   public Object getProperty(String propertyId)
 218:     throws SAXNotRecognizedException
 219:   {
 220:     if ((SAXDriver.PROPERTY + "declaration-handler").equals(propertyId)
 221:         || (SAXDriver.PROPERTY + "lexical-handler").equals(propertyId))
 222:       {
 223:         return filter.getProperty(propertyId);
 224:       }
 225:     throw new SAXNotRecognizedException(propertyId);
 226:   }
 227: 
 228:   private void forceValidating()
 229:     throws SAXNotRecognizedException, SAXNotSupportedException
 230:   {
 231:     aelfred2.setFeature(SAXDriver.FEATURE + "namespace-prefixes",
 232:                         true);
 233:     aelfred2.setFeature(SAXDriver.FEATURE + "external-general-entities",
 234:                         true);
 235:     aelfred2.setFeature(SAXDriver.FEATURE + "external-parameter-entities",
 236:                         true);
 237:   }
 238: 
 239:   /**
 240:    * <b>SAX2</b>:  Sets the state of features supported in this parser.
 241:    * Note that this parser requires reporting of namespace prefixes when
 242:    * validating.
 243:    */
 244:   public void setFeature(String featureId, boolean state)
 245:     throws SAXNotRecognizedException, SAXNotSupportedException
 246:   {
 247:     boolean value = getFeature(featureId);
 248: 
 249:     if (state == value)
 250:       {
 251:         return;
 252:       }
 253: 
 254:     if ((SAXDriver.FEATURE + "validation").equals(featureId))
 255:       {
 256:         if (active)
 257:           {
 258:             throw new SAXNotSupportedException("already parsing");
 259:           }
 260:         if (state)
 261:           {
 262:             forceValidating();
 263:           }
 264:         isValidating = state;
 265:       }
 266:     else
 267:       {
 268:         aelfred2.setFeature(featureId, state);
 269:       }
 270:   }
 271: 
 272:   /**
 273:    * <b>SAX2</b>: Tells whether this parser supports the specified feature.
 274:    * At this time, this directly parallels the underlying SAXDriver,
 275:    * except that validation is optionally supported.
 276:    *
 277:    * @see SAXDriver
 278:    */
 279:   public boolean getFeature(String featureId)
 280:     throws SAXNotRecognizedException, SAXNotSupportedException
 281:   {
 282:     if ((SAXDriver.FEATURE + "validation").equals(featureId))
 283:       {
 284:         return isValidating;
 285:       }
 286: 
 287:     return aelfred2.getFeature(featureId);
 288:   }
 289: 
 290:   /**
 291:    * <b>SAX1</b>: Sets the locale used for diagnostics; currently,
 292:    * only locales using the English language are supported.
 293:    * @param locale The locale for which diagnostics will be generated
 294:    */
 295:   public void setLocale(Locale locale)
 296:     throws SAXException
 297:   {
 298:     aelfred2.setLocale(locale);
 299:   }
 300: 
 301:   /**
 302:    * <b>SAX1</b>: Preferred API to parse an XML document, using a
 303:    * system identifier (URI).
 304:      */
 305:   public void parse(String systemId)
 306:     throws SAXException, IOException
 307:   {
 308:     parse(new InputSource(systemId));
 309:   }
 310: 
 311:   /**
 312:    * <b>SAX1</b>: Underlying API to parse an XML document, used
 313:    * directly when no URI is available.  When this is invoked,
 314:    * and the parser is set to validate, some features will be
 315:    * automatically reset to appropriate values:  for reporting
 316:    * namespace prefixes, and incorporating external entities.
 317:    *
 318:    * @param source The XML input source.
 319:    *
 320:    * @exception IllegalStateException if called mid-parse
 321:    * @exception SAXException The handlers may throw any SAXException,
 322:    *  and the parser normally throws SAXParseException objects.
 323:    * @exception IOException IOExceptions are normally through through
 324:    *  the parser if there are problems reading the source document.
 325:    */
 326:   public void parse(InputSource source)
 327:     throws SAXException, IOException
 328:   {
 329:     EventFilter next;
 330:     boolean nsdecls;
 331: 
 332:     synchronized (aelfred2)
 333:       {
 334:         if (active)
 335:           {
 336:             throw new IllegalStateException("already parsing");
 337:           }
 338:         active = true;
 339:       }
 340: 
 341:     // set up the output pipeline
 342:     if (isValidating)
 343:       {
 344:         forceValidating();
 345:         next = new ValidationConsumer(filter);
 346:       }
 347:     else
 348:       {
 349:         next = filter;
 350:       }
 351: 
 352:     // connect pipeline and error handler
 353:     // don't let _this_ call to bind() affect xmlns* attributes
 354:     nsdecls = aelfred2.getFeature(SAXDriver.FEATURE + "namespace-prefixes");
 355:     EventFilter.bind(aelfred2, next);
 356:     if (!nsdecls)
 357:       {
 358:         aelfred2.setFeature(SAXDriver.FEATURE + "namespace-prefixes",
 359:                             false);
 360:       }
 361: 
 362:     // parse, clean up
 363:     try
 364:       {
 365:         aelfred2.parse(source);
 366:       }
 367:     finally
 368:       {
 369:         active = false;
 370:       }
 371:   }
 372: 
 373: }