/*
* Copyright (c) 1998-2011 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.el;
import com.caucho.vfs.WriteStream;
import javax.el.ELContext;
import javax.el.ELException;
import java.io.IOException;
/**
* Base implementation for a boolean-valued expression.
*/
abstract public class AbstractBooleanExpr extends Expr {
/**
* Evaluate the expression as a boolean
*
* @param env the variable environment
*
* @return the value as a booleanstring
*/
@Override
abstract public boolean evalBoolean(ELContext env)
throws ELException;
/**
* Evaluate the expression as an object.
*
* @param env the variable environment
*
* @return the value as an object
*/
@Override
public Object getValue(ELContext env)
throws ELException
{
return evalBoolean(env) ? Boolean.TRUE : Boolean.FALSE;
}
/**
* Evaluate the expression as a string
*
* @param env the variable environment
*
* @return the value as a string
*/
@Override
public String evalString(ELContext env)
throws ELException
{
return evalBoolean(env) ? "true" : "false";
}
/**
* Evaluate the expression as a long
*
* @param env the variable environment
*
* @return the value as a long
*/
@Override
public long evalLong(ELContext env)
throws ELException
{
ELException e = new ELException(L.l("'{0}': boolean expressions can not be converted to long values.", this));
error(e, env);
return 0;
}
/**
* Evaluate the expression as a double
*/
@Override
public double evalDouble(ELContext env)
throws ELException
{
ELException e = new ELException(L.l("`{0}': boolean expressions can not be converted to double values.", this));
error(e, env);
return 0;
}
/**
* Evalutes directly to the output.
*
* @param out the output stream
* @param env the variable environment
*/
@Override
public boolean print(WriteStream out, ELContext env, boolean isEscaped)
throws IOException, ELException
{
if (evalBoolean(env))
out.print("true");
else
out.print("false");
return false;
}
}