// This file is copyrighted and is part of nzdis-oql package. 
// See the file LICENSE for copyright information and the terms and conditions for copying, distributing and modifications of nzdis-oql package.
// @copyright@

package nzdis.lang.oql;

/**/
import nzdis.lang.oql.analysis.DepthFirstAdapter;
import nzdis.lang.oql.node.*;
import java.util.Hashtable;

/**
 * Free variables extractor. Traverses the AST and collects all the
 * references to free variables. 
 *
 *@author Mariusz Nowostawski
 *@version @version@ $Revision: 1.1 $
 */
class FreeVariableWalker extends DepthFirstAdapter {

  /** 
   * String variable names without leading $ indexed by appropriate
   * AST nodes.*/
  private Hashtable variables = new Hashtable();

  /** Returns the variable hash. */
  public Hashtable getVariables(){
    return this.variables;
  }

  

  public void outALongParamExpr(ALongParamExpr node){
    this.variables.put(node, node.getLongLiteral().getText().trim());
  }
  
  public void outANamedParamExpr(ANamedParamExpr node){
    this.variables.put(node, node.getIdentifier().getText().trim());
  }
  
}