gomp-20050608-branch/libjava/classpath/gnu/xml/dom/ImplementationSource.java

   1 /* ImplementationSource.java --
   2    Copyright (C) 2004 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 package gnu.xml.dom;
  38
  39 import java.util.ArrayList;
  40 import java.util.Arrays;
  41 import java.util.Iterator;
  42 import java.util.List;
  43
  44 import org.w3c.dom.DOMImplementation;
  45 import org.w3c.dom.DOMImplementationList;
  46 import org.w3c.dom.DOMImplementationSource;
  47
  48 /**
  49  * Implementation source for GNU JAXP.
  50  *
  51  * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a>
  52  */
  53 public class ImplementationSource
  54   implements DOMImplementationSource
  55 {
  56
  57   private static final String DIGITS = "1234567890";
  58
  59   /*
  60    * GNU DOM implementations.
  61    */
  62   private static final DOMImplementation[] implementations;
  63
  64   static
  65   {
  66     List acc = new ArrayList();
  67     acc.add(new gnu.xml.dom.DomImpl());
  68     try
  69       {
  70         Class t = Class.forName("gnu.xml.libxmlj.dom.GnomeDocumentBuilder");
  71         acc.add(t.newInstance());
  72       }
  73     catch (Exception e)
  74       {
  75         // libxmlj not available
  76       }
  77     catch (UnsatisfiedLinkError e)
  78       {
  79         // libxmlj not available
  80       }
  81     implementations = new DOMImplementation[acc.size()];
  82     acc.toArray(implementations);
  83   }
  84
  85   public DOMImplementation getDOMImplementation(String features)
  86   {
  87     List available = getImplementations(features);
  88     if (available.isEmpty())
  89       {
  90         return null;
  91       }
  92     return (DOMImplementation) available.get(0);
  93   }
  94
  95   public DOMImplementationList getDOMImplementationList(String features)
  96   {
  97     List available = getImplementations(features);
  98     return new ImplementationList(available);
  99   }
 100
 101   /**
 102    * Returns a list of the implementations that support the specified
 103    * features.
 104    */
 105   private final List getImplementations(String features)
 106   {
 107     List available = new ArrayList(Arrays.asList(implementations));
 108     for (Iterator i = parseFeatures(features).iterator(); i.hasNext(); )
 109       {
 110         String feature = (String) i.next();
 111         String version = null;
 112         int si = feature.indexOf(' ');
 113         if (si != -1)
 114           {
 115             version = feature.substring(si + 1);
 116             feature = feature.substring(0, si);
 117           }
 118         for (Iterator j = available.iterator(); j.hasNext(); )
 119           {
 120             DOMImplementation impl = (DOMImplementation) j.next();
 121             if (!impl.hasFeature(feature, version))
 122               {
 123                 j.remove();
 124               }
 125           }
 126       }
 127     return available;
 128   }
 129
 130   /**
 131    * Parses the feature list into feature tokens.
 132    */
 133   final List parseFeatures(String features)
 134   {
 135     List list = new ArrayList();
 136     int pos = 0, start = 0;
 137     int len = features.length();
 138     for (; pos < len; pos++)
 139       {
 140         char c = features.charAt(pos);
 141         if (c == ' ')
 142           {
 143             if (pos + 1 < len &&
 144                 DIGITS.indexOf(features.charAt(pos + 1)) == -1)
 145               {
 146                 list.add(getFeature(features, start, pos));
 147                 start = pos + 1;
 148               }
 149           }
 150       }
 151     if (pos > start)
 152       {
 153         list.add(getFeature(features, start, len));
 154       }
 155     return list;
 156   }
 157
 158   final String getFeature(String features, int start, int end)
 159   {
 160     if (features.length() > 0 && features.charAt(start) == '+')
 161       {
 162         return features.substring(start + 1, end);
 163       }
 164     return features.substring(start, end);
 165   }
 166
 167 }