libjava/classpath/gnu/xml/xpath/LangFunction.java

   1 /* LangFunction.java --
   2    Copyright (C) 2004,2006 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.xpath;
  39
  40 import java.util.List;
  41 import javax.xml.namespace.QName;
  42 import org.w3c.dom.Element;
  43 import org.w3c.dom.Node;
  44
  45 /**
  46  * The <code>lang</code> function returns true or false depending on whether
  47  * the language of the context node as specified by xml:lang attributes is
  48  * the same as or is a sublanguage of the language specified by the argument
  49  * string. The language of the context node is determined by the value of
  50  * the xml:lang attribute on the context node, or, if the context node has
  51  * no xml:lang attribute, by the value of the xml:lang attribute on the
  52  * nearest ancestor of the context node that has an xml:lang attribute. If
  53  * there is no such attribute, then lang returns false. If there is such an
  54  * attribute, then lang returns true if the attribute value is equal to the
  55  * argument ignoring case, or if there is some suffix starting with - such
  56  * that the attribute value is equal to the argument ignoring that suffix of
  57  * the attribute value and ignoring case.
  58  *
  59  * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a>
  60  */
  61 final class LangFunction
  62   extends Expr
  63 {
  64
  65   final Expr arg;
  66
  67   LangFunction(List args)
  68   {
  69     this((Expr) args.get(0));
  70   }
  71
  72   LangFunction(Expr arg)
  73   {
  74     this.arg = arg;
  75   }
  76
  77   public Object evaluate(Node context, int pos, int len)
  78   {
  79     Object val = arg.evaluate(context, pos, len);
  80     String lang = _string(context, val);
  81     String clang = getLang(context);
  82     while (clang == null && context != null)
  83       {
  84         context = context.getParentNode();
  85         clang = getLang(context);
  86       }
  87     boolean ret = (clang == null) ? false :
  88       clang.toLowerCase().startsWith(lang.toLowerCase());
  89     return ret ? Boolean.TRUE : Boolean.FALSE;
  90   }
  91
  92   String getLang(Node node)
  93   {
  94     while (node != null)
  95       {
  96         if (node.getNodeType() == Node.ELEMENT_NODE)
  97           {
  98             String lang = ((Element) node).getAttribute("xml:lang");
  99             if (lang != null)
 100               return lang;
 101           }
 102         node = node.getParentNode();
 103       }
 104     return null;
 105   }
 106
 107   public Expr clone(Object context)
 108   {
 109     return new IdFunction(arg.clone(context));
 110   }
 111
 112   public boolean references(QName var)
 113   {
 114     return arg.references(var);
 115   }
 116
 117   public String toString()
 118   {
 119     return "lang(" + arg + ")";
 120   }
 121
 122 }