/* NamespaceUriFunction.java -- 
   Copyright (C) 2004,2006 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
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this exception to your version of the library, but you are not
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package gnu.xml.xpath;

import java.util.Collection;
import java.util.Collections;
import java.util.List;
import javax.xml.namespace.QName;
import org.w3c.dom.Node;

/**
 * The <code>namespace-uri</code> function returns the namespace URI of the
 * expanded-name of the node in the argument node-set that is first in
 * document order. If the argument node-set is empty, the first node has no
 * expanded-name, or the namespace URI of the expanded-name is null, an
 * empty string is returned. If the argument is omitted, it defaults to a
 * node-set with the context node as its only member.
 *
 * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a>
 */
final class NamespaceUriFunction
  extends Expr
{

  final Expr arg;

  NamespaceUriFunction(List args)
  {
    this(args.size() > 0 ? (Expr) args.get(0) : null);
  }
  
  NamespaceUriFunction(Expr arg)
  {
    this.arg = arg;
  }

  public Object evaluate(Node context, int pos, int len)
  {
    Object val = (arg == null) ? Collections.singleton(context) :
        arg.evaluate(context, pos, len);
    return _namespace_uri(context, (Collection) val);
  }

  public Expr clone(Object context)
  {
    return new NamespaceUriFunction((arg == null) ? null :
                                    arg.clone(context));
  }

  public boolean references(QName var)
  {
    return (arg == null) ? false : arg.references(var);
  }
  
  public String toString()
  {
    return (arg == null) ? "namespace-uri()" : "namespace-uri(" + arg + ")";
  }
  
}