content: // (c) ALEXANDRE BRILLANT : http://www.japisoft.com
  // All this work is confidential, you have rights to
  // change and evolve it for your products but you
  // have no rights to sell it, propose concurrent works.
  // Morever any changes to bugs or evolutions should
  // be send to JAPISOFT that needs to maintain a
  // valid version and has all rights on the product.
  
  
  package com.japisoft.xpath.function;
  
  import com.japisoft.xpath.NodeSet;
  import com.japisoft.xpath.XPathContext;
  import com.japisoft.xpath.FastVector;
  
  /**
  This program is available under two licenses : 
  
  1. For non commercial usage : 
  
  This program 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 3 of the License, or
  (at your option) any later version.
  
  This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
  
  2. For commercial usage :
  
  You need to get a commercial license for source usage at : 
  
  http://www.editix.com/buy.html
  
  Copyright (c) 2018 Alexandre Brillant - JAPISOFT SARL - http://www.japisoft.com
  
  @author Alexandre Brillant - abrillant@japisoft.com
  @author JAPISOFT SARL - http://www.japisoft.com
  
  */
  public abstract class AbstractFunction implements Function {
      public AbstractFunction() {
  	super();
      }
  
      /** Evalute this function for this context and the following arguments */
      public abstract Object eval( XPathContext context, FastVector arg );
  
      /** Throw a RuntimeException if arg has no single NodeSet argument */
      public void checkOneNumber( FastVector arg ) {
  	checkOneParameter( arg );
  	if ( !( arg.elementAt( 0 ) instanceof Double ) )
  	    throw new RuntimeException( "Invalid parameter in " + this );
      }
  
      /** Throw a RuntimeException if arg has no single NodeSet argument */
      public void checkOneNodeSet( FastVector arg ) {
  	checkOneParameter( arg );
  	if ( !( arg.elementAt( 0 ) instanceof NodeSet ) )
  	    throw new RuntimeException( "Invalid parameter in " + this );
      }
  
      /** Throw a RuntimeException if arg has no single argument */
      public void checkOneParameter( FastVector arg ) {
  	if ( arg.size() != 1 )
  	    throw new RuntimeException( "Invalid parameter in " + this );
      }
  
      /** Throw a RuntimeException if arg has no 1 string argument */
      public void checkOneString( FastVector arg ) {
  	if ( arg.size() != 1 )
  	    throw new RuntimeException( "Invalid parameters in " + this );
  	if ( !( arg.elementAt( 0 ) instanceof String ) )
  	    throw new RuntimeException( "Invalid parameters in " + this );
      }
  
      /** Throw a RuntimeException if arg has no 2 string arguments */
      public void checkTwoStrings( FastVector arg ) {
  	if ( arg.size() != 2 )
  	    throw new RuntimeException( "Invalid parameters in " + this );
  	if ( !( ( arg.elementAt( 0 ) instanceof String ) &&
  		arg.elementAt( 1 ) instanceof String ) )
  	    throw new RuntimeException( "Invalid parameters in " + this );
      }
  
      /** Throw a RuntimeException if arg has no 3 string arguments */
      public void checkThreeStrings( FastVector arg ) {
  	if ( arg.size() != 3 )
  	    throw new RuntimeException( "Invalid parameters in " + this );
  	if ( !( ( arg.elementAt( 0 ) instanceof String ) &&
  		( arg.elementAt( 1 ) instanceof String ) &&
  		( arg.elementAt( 2 ) instanceof String ) ) )
  	    throw new RuntimeException( "Invalid parameters in " + this );
      }
  
      /** @return only the class name without the package */
      public String toString() {
  	return getClass().getName().substring( getClass().getName().lastIndexOf( "." ) );
      }
  
      public java.lang.String getString1( XPathContext context, FastVector arg ) {
        return context.getStringValue( arg.elementAt( 1 ) );
      }
  
      public java.lang.String getString2( XPathContext context, FastVector arg ) {
        return context.getStringValue( arg.elementAt( 0 ) );
      }
  
  }
  
  // AbstractFunction ends here
  