/*
 * Copyright (c) 1998-2008 Caucho Technology -- all rights reserved
 *
 * This file is part of Resin(R) Open Source
 *
 * Each copy or derived work must preserve the copyright notice and this
 * notice unmodified.
 *
 * Resin Open Source 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 of the License, or
 * (at your option) any later version.
 *
 * Resin Open Source 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, or any warranty
 * of NON-INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Resin Open Source; if not, write to the
 *
 *   Free Software Foundation, Inc.
 *   59 Temple Place, Suite 330
 *   Boston, MA 02111-1307  USA
 *
 * @author Scott Ferguson
 */

package com.caucho.quercus.expr;

import com.caucho.quercus.Location;
import com.caucho.quercus.env.Env;
import com.caucho.quercus.env.NullValue;
import com.caucho.quercus.env.Value;

/**
 * Represents unsetting a PHP variable
 */
public class UnsetExpr extends Expr {
  private final AbstractVarExpr _var;

  public UnsetExpr(Location location, AbstractVarExpr var)
  {
    super(location);
    _var = var;
  }

  public UnsetExpr(AbstractVarExpr var)
  {
    _var = var;
  }

  /**
   * Evaluates the expression.
   *
   * @param env the calling environment.
   *
   * @return the expression value.
   */
  public Value eval(Env env)
  {
    _var.evalUnset(env);

    return NullValue.NULL;
  }

  //
  // Java code generation
  //

  /**
   * Analyze the expression
   */
  /*
  public void analyze(AnalyzeInfo info)
  {
  }
  */

  /**
   * Generates code to evaluate the expression
   *
   * @param out the writer to the Java source code.
   */
  /*
  public void generate(PhpWriter out)
    throws IOException
  {
    String name = _var.getName();
    
    VarState state = _var.getVarState();

    if (state == VarState.UNSET) {
    }
    else {
      if (_var.getVarInfo().isGlobal()) {
        out.print(_var.getJavaVar());
        out.print(" = env.unsetVar(\"");
        out.printJavaString(name);
        out.print("\")");
      }
      else {
        out.print(_var.getJavaVar());
        out.print(" = null");
      }
    }
  }
  */

  public String toString()
  {
    return "unset(" + _var + ")";
  }
}