Source for gnu.xml.xpath.IdFunction

   1: /* IdFunction.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: 
  38: package gnu.xml.xpath;
  39: 
  40: import java.util.Collection;
  41: import java.util.List;
  42: import javax.xml.namespace.QName;
  43: import org.w3c.dom.Node;
  44: 
  45: /**
  46:  * The <code>id</code> function selects elements by their unique ID.
  47:  * When the argument to id is of type node-set, then the result is
  48:  * the union of the result of applying id to the string-value of each of the
  49:  * nodes in the argument node-set. When the argument to id is of any other
  50:  * type, the argument is converted to a string as if by a call to the string
  51:  * function; the string is split into a whitespace-separated list of tokens
  52:  * (whitespace is any sequence of characters matching the production S); the
  53:  * result is a node-set containing the elements in the same document as the
  54:  * context node that have a unique ID equal to any of the tokens in the
  55:  * list.
  56:  *
  57:  * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a>
  58:  */
  59: public final class IdFunction
  60:   extends Pattern
  61: {
  62: 
  63:   final Expr arg;
  64: 
  65:   IdFunction(List<Expr> args)
  66:   {
  67:     this(args.get(0));
  68:   }
  69: 
  70:   public IdFunction(Expr arg)
  71:   {
  72:     this.arg = arg;
  73:   }
  74: 
  75:   public boolean matches(Node context)
  76:   {
  77:     Object ret = evaluate(context, 1, 1);
  78:     return !((Collection<?>) ret).isEmpty();
  79:   }
  80: 
  81:   @Override
  82:   public Object evaluate(Node context, int pos, int len)
  83:   {
  84:     Object val = arg.evaluate(context, pos, len);
  85:     return _id(context, val);
  86:   }
  87: 
  88:   public Expr clone(Object context)
  89:   {
  90:     return new IdFunction(arg.clone(context));
  91:   }
  92: 
  93:   public boolean references(QName var)
  94:   {
  95:     return arg.references(var);
  96:   }
  97: 
  98:   public String toString()
  99:   {
 100:     return "id(" + arg + ")";
 101:   }
 102: 
 103: }